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RECORD
of unequalled
has won for the
Grebe Receiver the unqualified endorsement of all good dealers.
ALONG
performance
"Musings of Doctor
Mu"
the
story of the development of the Perfect Receiver, free upon request.
A. H.
GREBE
RICHMOND
& CO.
HILL, N. Y.
Licensed under
Armstrong U. S,
Pat,
No. 1113149
'
PUTTING THEIR HEADQUARTERS STATION ON THE MAP
Boy Scouts
of
Troop i, Roslyn, Long Island, using a loop receiver to determine the position of
their transmitting station at troop headquarters.
Bearings taken from two or more locations
are plotted on the map; and the point where these direction lines meet indicates the
position
of the transmitting station.
Left to right: Scouts Denton, Fontaine, Miller and Malmros
RADIO
BROADCAST
Vol. 2
No. 4
February,
The March
of
192;
Radio
"DRY-CELL TUBES" FOR RECEIVING
^HE
T
vacuum-tube is so far superior for
distance work and selective tuning to
the crystal detector that no comparison can be drawn as to their relative
The crystal set makes availmerits.
able in the telephone receivers a certain small
part of the radio power picked up by the antenna, perhaps a fraction of one thousandth of a
watt.
The amount of power which the antenna
can pick up decreases rapidly as the distance
from the transmitting station increases, and
this fact generally limits the use of the crystal
detector to points fifty miles or less from the
broadcasting station.
The vacuum-tube
receiver
works
on an
entirely different principle; in the B battery is
stored energy millions of times greater than
that picked up by the antenna and the tube acts
as a trigger to this local energy supply, changing the rate of energy flow from the B battery
accordance with the potential of the grid
which itself is excited by the minute energy
picked up by the antenna. Thus a tube set
may make audible a signal of perhaps one
millionth the strength necessary for audibility
with a crystal set. Why then is it that the
crystal set has any chance at all in the competiin
tion?
To this question there are several possible
answers, the principal one being that of cost,
both the first cost and the maintenance. A
can be purchased for $25 and no
apparatus is required, whereas a
fair crystal set
auxiliary
corresponding tube set would cost perhaps
$100 itself and in addition there must be
purchased a storage battery and plate-circuit
battery before it can function. The storage
battery for the filament circuit is expensive,
messy and inconvenient to care for, and is
a continual source of expense because of the
The B battery will
required.
only about one year before it becomes
Tubes burn
noisy and it must then be renewed.
out occasionally and many, people find it
very difficult to keep supplied with them.
One of the great advances in tube manufacture has recently been made available with
the appearance on the market of the WestingIn this tube the
house "dry-cell tube."
filament is coated in such a way that the emission of electrons occurs at the required rate
at a low temperature: in fact, the filament has
re-charging
last
no
visible glow in daylight, requires only one
quarter of an ampere to heat, and has a low
enough resistance to allow the voltage of one
dry cell to force the required current through
it.
The power used in this filament is therefore
about 0.3 watt, whereas the tungsten filament
tubes ordinarily used require about 7 watts for
the filament. The new tube therefore represents a decrease in the required filament
power in the ratio of twenty to one. One sixinch dry cell is sufficient to excite the filament
for
from
fifty
to one hundred hours, depending
used.
is
upon how continuously the tube
The first cost and the recharging
cost of a
Radio Broadcast
268
storage battery are done away with and the
single-tube receiving set, having a receiving
range of a hundred miles or more, need be
but little more expensive than the better
From what tests we have been
make, these new tubes should function
crystal sets.
able to
about as well as the older type, both as detectors
and amplifiers.
While in conversation with one of the research workers engaged in tube manufacture
and development, we were told recently that a quarter of an ampere
for the filament is much more than
necessary that one twentieth of an
permitting the use of alternating
current to heat the filament of the detecting
tube.
The technical value of this new deprinciple,
parture in tube manufacture may not seem
evident at once, but when it is seen that such
a tube makes it possible to obtain all the power
required, both for filament and plate circuits,
from the ordinary house wiring with its alternating current power supply, some appreciation of the role it may play in receiving sets will
be gained.
A receiver, amplifier,
and loud speaker, all operated from
an ordinary lamp socket
deed sounds attractive.
that
in-
the filament
is plenty for
a satisfactory receiving tube!
So events in the vacuum-tube field
There is
apparently nothing to prevent such
a combination except the policy of
the manufacturer in pushing the de-
are crowding one another very rapIt is really very difficult for
idly.
velopment of these new uni-potential
cathode vacuum tubes.
ampere
of
the manufacturing company to decide
when and how to start a new tube in production, for no sooner are the dies, jigs, and processes perfected than the research man reports
a new development which indicates that previous types should be discarded!
an expensive process for the manufacturer to cease production on one type and begin
on another. Of course, the buying public
must eventually pay the cost, and it is not to
It is
be expected therefore that the price of the new
tubes will be materially lower than that of the
present ones, until enough of them have been
sold to pay for the development costs.
Judging from the present rate of progress, the new
tube will be discarded for a superior one before
that point is reached.
Soon after the foregoing was written, Dr.
A. W. Hull, of the research laboratory of the
General Electric Company, justified the ideas
there set forth by reading before the Institute
of Radio Engineers a paper on a new tube he
had developed during the past few months.
Some years ago J. H. Morecroft pointed out
several of the advantages to be gained by
having a uni-potential cathode in a vacuum
tube and actually constructed such a tube by
putting the hot filament inside a tungsten
thimble.
The filament heated the thimble by
radiation and this hot thimble served as the
source of electrons. As no current was flowing,
along the thimble the resistance drop in the
filament was zero and certain defects in the
characteristics of the ordinary hot filament
tube were eliminated. Dr. Hull has succeeded
in developing a small receiving tube on this
The Standing
of the
Amateur
are emanating from Washing-
ton which indicate that the legal status
of the amateur is being seriously threat-
RJMORS
ened, and that
curtailed.
It
his
would
activities
be
a
may
be
much
serious
mistake,
we believe, to hamper unnecessarily the activities of these enthusiasts who have done so
much in short-wave telegraphy during the
The present radio public
course be properly served, but the
amateur, who studied and worked at the game
long before the public was interested, has
contributed a great deal, directly as well as
last
must
twenty years.
of
indirectly.
By an amateur we don't mean
the ten-year-old boy of your neighbor, who
starts up a one-kilowatt spark set just when
your family is enjoying an opera by radio,
or when you are trying for a long distance
record.
We think that this kind of nuisance
should be done away with at once, to keep the
musical programmes free from spark splashes.
A small boy with a big spark set is certainly a
misfit in the present scheme of radio.
Many amateurs, however, are radio engineers,
skilled in both the theory and practice of the
art, and their activities do much to extend our
knowledge of radio. They were the first to show
the possibility of transatlantic communication
by low powered, short-wave sets. In the tests
recently inaugurated 33 American amateur stationswere copied in England in the course of one
day only, stations even as far away as California
This year a one-kilowatt
being heard there.
The March
of
Radio
269
English station has been equipped to try the
transmission in the opposite direction and
undoubtedly
pick up
many American amateurs
its signals.
will
In a recent all-American
test, amateurs sent a message from Hartford,
Conn., to Hawaii and return in four minutes!
Radio workers who, by their enthusiasm,
financial aid, and skill are performing these
remarkable feats should be governed by legal
measures only to the extent absolutely necessary for the development of short-wave transmission.
A New Type of Power Tube
THE time that Dr. Hull was announcing
the new detecting tube described above,
the press contained a report of another
development which had taken place in the same
laboratory a power tube capable of delivering
one million watts of high-frequency power.
This is not an ordinary three-electrode tube;
it has only a filament and
plate, the filament
being a piece of tungsten rod nearly half an
inch in diameter!
The action of this tube can be well visualized
only by those who have become accustomed to
the idea of electrons and their actions in
A^
magnetic and
tioning of this
picture.
The
new tube
presents a fascinating
filament is heated by a high-
frequency current, of a frequency half of that
which
it is desired to
generate; the cylindrical
plate surrounding the filament is maintained
positive with respect to the filament at about
ten thousand volts. The electrons evaporated
from the hot filament tend to proceed at once
the plate, and they do so
unless the current in the filament exceeds a
certain critical value.
The filament current,
being alternating, passes through all values
along radial
lines to
between its maximum positive and negative
values twice per cycle, and this new tube is so
designed that at the maximum values of current the magnetic field set up around the
filament by its own current is sufficient to
deflect the electrons from their normal path
to the plate and make them describe curved
paths which land them back in the filament,
a short distance farther along than the point
at which they evaporated.
Their motion is
much
TWO GIANT POWER TUBES
electric fields; to such the func-
small
is
shown
tube
comparison
receiving
in
gravity, break through the surface, and
"evaporate" into the air; here they describe a
curved path which lands them back in the ocean
a few feet farther along than the point where
they left it, only to "re-evaporate" perhaps a
few hundred feet farther along their course.
of
In the case of the tube, during that part of
the cycle when the filament current has low
values, the electrons are not going back to
the filament and so do get over to the plate.
This action results in a series of pulses of
current being delivered to the plate circuit,
which pulses
may
be used to excite powerful
tuned circuit. In this
oscillations in a properly
new tube the magnetism generated by the
filament current itself performs the same function as does the grid in the ordinary threeelectrode tube.
Where
like that of a school of flying fish follow-
ing a ship: they swim swiftly toward the surface of the ocean, arrive at the surface with
sufficient
velocity to overcome the effect
A
is
the Radio Bill?
many months we have
been waiting
for Congress to do something with the
radio bill.
It was introduced in
the
FOR
House early
in June; in its substance
it
had the
Radio Broadcast
270
endorsement of the membership of the Radio
Conference called by Secretary Hoover to
consider what should be done to further the
riously crippled the western land lines, but the
International News Service was able to maintain 100% activity through the help of the
progress of radio.
The bill as at first drafted by Mr. White was
submitted to the Radio Conference. This
Radio Corporation stations. It is stated that
the transcontinental business, handled over
radio channels on short notice, was carried out
body approved it generally, and made a few
recommendations regarding minor changes,
which were incorporated in the bill in so far as
the advisory legal committee felt it possible
to do so. The bill, then, represents
successfully that the New York to San
Francisco service was as good as is obtained
with the land lines in normal condition.
so
To
fill
the best thought of those executive
in
The
America.
delayed service,
little
vice,
alike.
there no action of the White
is
bill?
The Rapid
A
FEW
Increase in Radio Traffic
months ago the statement was
made by
President
Carleton,
of
the
Union Telegraph Company
that transoceanic communication was practiWestern
cally monopolized by the cables, that radio
carried only 12% to 14% of the total business.
Now we
have the statement of Mr. David
Sarnoff, Vice-President of the Radio Corporation, that of the transatlantic business radio
is
handling from
pacific business,
25%
50%.
to
30% and of the transEven allowing for the
natural inclination of each of the proponents
exaggerate somewhat the importance of
his own field, it seems that radio is actually
making rapid strides in the race for long distance traffic.
During the recent elections, storms seto
filing
week and
or nothing is apdone to get the
by deserving henchmen; its passage would
apparently benefit Democrat and Republican
then,
a word to
This new ser-
six cents
styled
permits the
yet
bill
parently being
put
through. With the bill passed, the wave-band
allowed for broadcasting would be considerably
widened over its present limits and practically
all trouble from interference would disappear,
even for the unskilled novice. The amateur
investigator would have more latitude than he
now has. So far as a layman's perusal of the
measure discloses there is no political advantage to be gained by hindering the passage of
the bill; it will not create new offices to be filled
Why,
the
"radio letter" service,
of a message, in
plain English, any time during the
present legal status
is
effect,
idle periods,
England or Germany.
most deplorable, compared to what it might be if the
provisions of this bill were put into
radio
comparatively
Radio Corporation is offering a new
and remarkably low rate-schedule for
and technical experts who have had
most to do with radio development
of
in its
delivery in Europe is
before
the following Monguaranteed
day morning.
valuable
Undoubtedly
this
will
prove
business houses with European
connections; it permits the closing of a deal
without delay, at a cost but slightly exceeding
that of the much slower mail service.
to
Copyright for Broadcast Material
TH E
request of the American Society of
Composers, Authors, and Publishers, a
meeting was held recently to consider the
question of collecting royalties from the broadcasting stations which are sending out, by phonograph or otherwise, material which has been
A'
copyrighted by any of the members of the sociThe society controls, through its memberety.
ship, the copyrights on practically all the popular
music of the day, including the so-called jazz
music.
No agreement was reached as the representatives of the broadcasting companies required
time to consider the proposition; many interesting views on the question, however, were
brought out. The Society wanted to exact
from a station a flat royalty rate, depending
upon the number of listeners; such a measure
evidently didn't look attractive to the broadcasters at this time because as this society
controls but a small part of the material sent
out, and as other composers and publishers
have rights similar to those of the jazz writers,
the total royalties which might be exacted under
such a scheme might run into large figures.
Mr. Townley, for the Westinghouse Company, outlined the broadcasting situation very
well and pointed out to the attorneys for the
The March
of
Radio
271
jazz writers that the broadcasters
in a quandary as to where the
were
money
tions
for the operation of the sta-
was coming from even with the
let alone the extra
expense which would be incurred by
present expense,
royalty
collections.
company had
and
sets,
the
sold
Although
his
many
receiving
indirectly produced
for running the trans-
this
money
mitting stations, probably hundreds
of thousands of sets
were sold by
who had no
connection at
others
with a broadcasting station and
whom copyright royalties evidently could not be collected.
We believe the society of jazz
all
from
and publishers would do well
not to press the matter; legally they
artists
cannot collect royalties from an acwhich yields no profit and it
is doubtful if the balance sheets of
tivity
of the broadcasting stations
If the jazz is
to-day show a profit.
played at the transmitter station
from a phonograph the artist has
already collected one royalty and if
the artists themselves appear at the
station to perform, the advertis-
any
ing they get probably pays
their trouble, otherwise
for
them
they
would not come.
A STRIKING PHOTO OF THE
Power Transmission by Electron
Tubes
the advent of the
recently developed tubes
which have outputs reckoned in hundreds of kilowatts, there
has appeared several times in the
WITH
press the statement that these tubes
would soon make possible the transmission of power by radio; some
WRECKED
S.
S.
WILTSHIRE
Some may have
read the account of this shipwreck which occurred
during a dense fog and terrific gale last June off the east coast of New
Zealand.
Mr. Harmon Reeves, Consular Agent at Dunedin, N. Z.,
writes with reference to this event:
"The wireless operators on the
Wiltshire stood to their posts manfully, as most of these operators do on
such occasions, and continued to despatch SOS calls as long as the plant
remained in working order. Had the vessel been without wireless, it is
more than likely not a man on board the ill-fated vessel would have been
saved."
Reaching the island and working under great difficulties, a
rescue party finally saved the men in the manner shown.
The picture
shows the two junior operators being hauled ashore. (See Photo on
Page 273)
seemed to quote eminent engineers
effect.
It seems extremely unlikely
that such predictions were ever made; the
radio signal is an illustration of the action.
But of the hundreds of watts sent out from a
transmitting station only an infinitesimal part
economical transmission of power by radio
is no nearer solution to-day than it was when
that brilliant scientist-engineer, Nikola Tesla,
is
articles
to that
performed
his well
known experiments
in this
field.
We
say "economical transmission" of power
of course, power is actually
being transmitted, by radio, every day; every
by radio because,
picked up by a receiving antenna. Even
action of all the receiving
antennas is considered, the power sent out from
the transmitter is nearly all wasted in empty
The very fact that the power is
space.
when the combined
radiated, or set free, to travel in an essentially
spherical distribution, at once discourages the
engineer
who
has ideas along this
line.
The
Radio Broadcast
272
reason we use power transmission lines is to
guide the electrical energy to the point where
it is to be utilized; radiated energy is subject
to no such constraint and it naturally tends
to flow equally in all directions.
The reason the large electron tubes were at
once associated with the idea of power transmission is that they are able to fill important
roles in the present transmission line projects;
these new tubes may serve as rectifiers at
the generating station, changing the
alternating-current power of the generators to high-voltage continuouscurrent power for transmission over
the long power lines and then re-
convert
into
it
quality of the voice could be completely spoiled
by poor wire transmission before it even reaches
Under these conditions the
the radio station.
no
will
be
matter how excellent the
poor
signal
radio station itself may be.
Thus if a trans-
mitting
wire,
This use of the electron tube
seems to be a logical, in fact, almost
certain development; continuous-current power
can be economically carried over transmission
much
greater distances than is possible
alternating current, and because of this
new tubes may soon be serving in new
long distance power developments; the power
will not be transmitted as high frequency,
radiated power, however, but as continuousfact the
current power, guided by transmission lines of
ordinary construction.
allowed to broadcast only from microphones located at the station, so that the
wires connecting the microphones with the
modulator can have no bad effect on the
Broadcasting from a
quality of the signal.
distant microphone should be attempted only
by that station having the highest grade wire
In this way alone will
connections available.
the quality of broadcasting improve as we
should like to see it.
The Passing
;
of the
Navigation Officer
Fewer and Better Broadcasting Stations
navigator
-!,~
HAVE
E
several
times expressed
our views on this question, and as
we see the art develop, our convicline become more firmly
technically possible to send
out broadcast messages of excellent quality,
as the achievements of station
(N. Y.
tions
fixed.
this
along
It
is
now
WEAF
City), for instance, have proved. The engineers
responsible for this station evidently know the
requirements for good voice transmission and
have succeeded in getting it. Of course they,
of all people, should be able to do just this thing;
their research workers have, spent years in
studying this problem and their engineers know
what voice frequencies are important and what
are not and how to make the microphones and
associated apparatus function properly.
Another important factor contributing
,
the success of
WEAF's
broadcasting
is
to
the
and control over high quality
knowledge
Many times the microphone
telephone lines.
which picks up the sound waves is miles away
from the radio station and evidently the
of
its
signal over a
installed to handle
grade line available to bring the voice
If this is
currents to the modulator.
not feasible, such a station should be
alternating-current
it is to be
used.
by
receives
ordinary land telegraphy only sufficiently well,
instead of getting the signal over what is called
a high quality telephone circuit, the broadcasted signal will be of poor quality.
Some kind of an agreement should
be reached between the various interests involved so that any qualified
radio station may use the highest
power at the place where
lines
station
hundred miles of
vessel probably
THE
of
the
knows
modern ocean
his position at all
times to within a very few miles, no
matter what the weather is. Time was, when
it was a matter of guesswork as to what weather
a ship was going to encounter and as to just
when land would be sighted. Radio is largely
responsible for the increased certainty of the
Are the chroship's position and prospects.
nometers correct? Twice a day they may be
checked with the standard clocks, which, by
radio dashes, throw out their reassurance over
Is
the thousands of square miles of ocean.
there rough weather with storms ahead? A
radio inquiry to a ship 500 miles ahead on the
course at once eliminates the doubt. The
"make everything fast" order may be given
long before a threatening sky gives warning of
How about the ship's
the impending blow.
the
harbor? A request
when
nearing
position
for radio compass bearings will enable the
navigator to locate his position on the chart to
within a fraction of a mile.
may
The
radio compass
then pick up and follow the
hum
of a
The March
submerged cable laid in the channel, sending off
audio-frequency signals, and thus it may steam
into the harbor without ever having sighted
land.
All these things have already been accomplished, and are in use every day. They
are not the possible, but the actual things
science has accomplished during the last quarter
century.
And now there comes to the further aid of
the navigator another scheme of communication which will help to make his position doubly
As a result of certain researches carried
sure.
on during the war, part of which have been
disclosed, it is possible to get soundings of the
ocean's depth by echoes. A sound-generating
apparatus in the ship's hull sends straight
downwards a pulse of sound which will reflect
from the ocean's bottom and return to the ship
to actuate a microphone which produces the
echo for the listening operator. The time
elapsing between the sending of the original
signal and the return of the echo serves to
The
give accurately the depth of the ocean.
ocean's floor can now be accurately and quickly
mapped and accurate charts of its topography
can be plotted; the navigating officer then
of
Radio
times the sound on its trip to the sea-bottom
and back to the surface, and by comparison
with the chart he at once checks his position
which has been determined by other methods.
For shallow water where the echo would
return too rapidly to permit an accurate determination of the time taken for the sound
to travel to the bottom and back, another
scheme is used, which does permit of very
accurate measurements of the depth. A
special listening device is located at the bottom
of the vessel and it can be so turned that the
listener hears the echo of the screw of his own
vessel, this echo having been sent back by the
ocean's bottom.
Knowing the angle to which
the device must be turned to get a maximum
echo, and the length of the ship, the depth of
the water can be determined to less than a
fathom.
During certain tests in which the writer
took part, it was found possible to recognize
the ship's position in the harbor by the quality
of the echo returned by a sound beam sent
in towards the shore; in certain positions only
one sharp echo would return, in others perhaps
three or four, of different intensity and in some
Here,
positions no echo at all came back.
THE MORNING AFTER THE NIGHT BEFORE
Wiltshire divided into three sections; the stern has disappeared.
The men,
had suffered frightfully from exposure, hunger, and thirst for 36 hours, were all saved
Showing the
who
S. S.
273
Radio Broadcast
274
is another possible help to the navigator.
seems that the days of lead lines and dead
then,
It
reckoning are rapidly being relegated to the
The navigating officer practicto
use his judgment in finding
has
never
ally
modern communication
his position; with
schemes he knows.
tales of the sea.
facilities,
market conditions,
etc.,
which
may
be received by radio make the investment pay.
On such boats skilled surgical or medical advice
may now generally be tuned in cases are being
reported daily of emergencies being successAn example
fully met by advice sent by radio.
is that of a man whose broken leg was ampu;
tated by the cook; a description of the condition
Radio Surgery and Doctoring
of the injured man having been sent by radio
to the surgeon on a liner 200 miles away, de-
maritime law requires that any ship
carrying passengers shall have a doctor
on board, but there are thousands of
vessels such as freighters, tankers, fruit boats,
fishing schooners, tramps, etc., which carry no
doctor; a case of pneumonia or a broken leg
tailed directions for the operation were wirelessed back and the cook (already equipped
THE
ship's cook, or someone
equally unskilled in the practice of medicine. A
patient's chances of adequate attention are
evidently rather slim.
Many of these boats do carry a radio outfit,
must be treated by the
however, and more of them are continually
installing equipment, for reports on docking
with
site is the
many
thrills,
successfully
"did
dictates of his
2,
the
own
inspiration.
With an adequate medical outfit on board
and a good doctor within radio range, the
wants of the crew of the doctorless boats
will
be much better taken care of than they have
been in the past.
J. H. M.
IN
THE WORLD
Workmen erecting
100 feet above the city of Rio de Janeiro, Brazil.
when the slightest mis-step would have meant a plunge to the depths below
peak of Mt. Corcovado,
the aerials experienced
tools)
We may not relish the idea of being put
through such an operation, but if it is necessary,
the radio instructions without doubt make the
cook a safer bet than if he were left to the
THE HIGHEST RADIO STATION
The
suitable
"
trick.
The Boy
Scout's Place in the
Radio
By
Game
ARMSTRONG PERRY
Sea Scout Radio Commodore, Boy Scouts of America
THIRTEEN
out of every hundred of
the radio listeners who cussed at the
Government for putting a talk on
cancer into the air the other night at
the beginning of the radio concert
hour, will die of cancer unless they can secure
the repeal of the law of averages. The only
way to avoid it is to acquire individually the
information broadcasted at that time and live
when
to it.
Pneumonia, typhoid, tuberculosis,
heart disease and kidney diseases will carry off
a large percentage of the remainder, and will
Government Printing
T
up
do
it years earlier than they need to, unless
they take the common-sense precautions suggested in the broadcasts of the United States
Public Health Service.
One hundred per cent, of the commuters
who missed their trains yesterday and blamed
the erratic alarm clock could have reached the
office on time if they had spent a minute or
so listening to the clock at the Naval Observatory in Washington announcing the hour
at ten the evening before.
It can be heard in
any American home,
for its ticks are carried
to the remotest corners of our country on radio
rolling out from the Navy station at
waves
Arlington, Virginia and others along all our
coasts.
These same commuters could have
carried their umbrellas and avoided their last
wetting if they had spent as much time practicing the International Morse Code as many of
them spent on bridge, and listened for the
weather forecast that followed the time signal.
In fact they need not have learned code, for
there is a boy in every neighborhood who would
get
easily and who would delight in
copying code broadcasts and passing the information to his neighbors if he had a little
it
more
encouragement.
Out
of the ninety per cent, of business men
a failure of their enterprises, accord-
who make
ing to statistics, a fair proportion might win
success by making intelligent use of information
that is collected on an enormous scale by our
Government and shot out
radio
or
held
in
in concise
form by
day
reserve awaiting the
the public asks for
citizen out of every 157
is
One American
it.
an employee of the
Federal Government and a large part of the
672,953 persons on the pay roll are engaged in
collecting, tabulating,
information.
received,
By
and disseminating
radio
and used
it
in less
useful
can be transmitted,
time than it takes a
messenger to carry copy for a Government
pamphlet from a Department building to the
And
Office.
with true American prodigality, a
lot of us twist the knobs on our radio receivers, screw up our faces and superheat our
tempers in trying to tune out the Government
broadcasts, and as a nation we permit more
than two hundred efficient Government radio
stations to stand idle for forty per cent, of the
time, when they might be adding to our enyet,
joyment and prosperity. Worst of all, we
waste almost one hundred per cent, of a natural
resource more valuable even than our much
discussed water power, namely, our boy power.
The present-day
of
diverse
radio situation
elements. There are
is
made up
well-estab-
lished governmental and commercial services
which only a few far-sighted individuals are
using fully. There are the commercial broadcasters who bear an enormous expense in filling
the air with entertainment that sells their comThere
petitor's goods as well as their own.
are manufacturers and dealers who never know
exactly whose alleged rights they may be in-
fringing when they sell a piece of apparatus
that has been made in cruder form by thou-
sands of boys without let or hindrance. There
the amateurs and experimenters, the
pioneers of radio, who, from the often unjust
viewpoint of listeners who are interfered with
by their dots and dashes, are as exasperating
as the mosquitoes whose hum their code resembles. Outnumbering all the rest are the
are
whose aim when they sit down at
to be amused.
A theatrical manager who built a stage and
dressing rooms but no orchestra section, balcony or box office would be called a fool. A
radio users
their sets
is
Radio Broadcast
276
SCOUTS RECEIVING INSTRUCTIONS
Members
of this St. Louis troop took
up radio
IN
VARIOUS SYSTEMS OF SIGNALING
a long time ago.
The
picture
was made
in
January, 1914
college that provided courses and faculty but
enrolled no pupils, leaving the matter of attendance up to the loiterers who drifted by,
would be held up to ridicule.
newspaper
who were registered with the
give them the piquancy of secrecy they were often transmitted in a code
which could be readily translated only by the
on the street
seldom taken seriously by its
readers and never by the reliable advertiser.
Yet millions of dollars yearly are being spent
in broadcasting entertainment and information
by radio with no more definite or complete
checkup as to results than the post-cards and
use of a key furnished to the members of the
Bureau. Sometimes a message was addressed
A
that gives
away
free of charge
its
daily edition
is
by those who listen.
So far as has been discovered, the first suggestion to the effect that there should be organization at the receiving end of the
broadcasting came from the Boy Scouts of
America. Or it might be more just to give the
credit to the Navy Department.
During the
war the Navy and the Army found that the
main source of supply for competent radio
letters sent in
to the amateurs
To
Bureau.
personally to an individual.
One of these messages was picked up by a
He copied the amateur broadscout official.
cast night after night thereafter, became con-
vinced that the system had great value, and
scraped acquaintance with the Navy officers
in charge.
The Navy
officers,
limited as to
appropriations, suggested that the Boy Scouts
the largest uniformed force,
of America,
United States, might
be of service by encouraging the registration
of amateurs with the Bureau.
Immediately
the Scout organization accepted the assignment. A Seascout Radio Commodore was
civilian or military, in the
"amateur." These amawere self-taught, came
forward in large numbers and filled the gap
while the Government and private schools
were getting under way with the task of developing operators and radio experts by thou-
appointed to serve as a liaison officer. To give
the arrangement greater force the Bureau began
broadcasting for the Scout organization anything it wished to transmit to its local units.
This all happened four years ago.
Since then the Army, the Post Office De-
sands.
After the war, the Navy planned to
conserve the interest of the coming generation
of amateurs by organizing a Radio Amateur
Bureau in the Third Naval District and transmitting daily an Amateur Broadcast. These
broadcasts were in a sense personal messages
partment, and other governmental departments have established broadcasting schedules.
personnel was the
teurs,
most of
whom
The Boy Scout organization, with these programmes as additional talking points, has
redoubled
others
its efforts
interested
in
to encourage Scouts and
radio to receive what
The Boy
the
Government transmits and
Scout's Place in the Radio
give
it
Game
277
local
distribution.
Having more than half a million Scouts and
Scout officials distributed throughout the
United States in more than 20,000 communiperhaps the only civilian organization
a position to develop local receiving
stations for national broadcasting on a naties, it is
that
is
in
tional scale.
the
The Post
only governmental
Office
Department is
agency that has as
many representatives so well distributed for
the purpose.
"
"
The cute little Boy Scout, as doting grandmothers and enthusiastic aunties are apt to
call him, is in fact almost a man.
His average
the
same
is
about
as
that
of
age
George Washington at the time when he surveyed a large
part of the Shenandoah Valley for Lord Fairfax.
It is above fifteen and one-half years.
While
with
M.
C.
recently
scouting
Hopkins, President of the Cave Men's Club of America, the
author found the name of the Father of his
Country carved on the wall in the remotest
chamber of a cave near the end of the 1748
survey, together with what appeared as though
might be the skull of a goat used in the
Masonic ceremonies that old histories say
Washington conducted in this chamber. He
it
concluded that the boys of pre-Revolutionary
days were much the same as the Scouts of today, except that their elders granted them more
freely the privilege of undertaking man-sized
jobs.
The Radio Amateur Bureau, for the further
encouragement of operating ability on the part
of radio scouts, reserved the numbers from
to 100 on its membership list for Scouts who
would learn to send and receive code at the
One of the
rate of twenty words per minute.
first
scouts to meet the requirements was
i
F. Barry of New York.
Scout Barry's record is an example of the
way many Scouts are going after radio, heart
Lyman
and
soul.
He
received his
first
radio training
Scout troop and built a crystal set at his
home in 1917, getting it into operation just
about in time to dismantle it in obedience to
He
the war order issued by the Government.
and
after
war
code
the
his
practice
kept up
often operated the headquarters transmitting
station of the Manhattan Association of Radio
in his
amateur operator's
with
the
Radio Amateur
license.
Registering
Bureau some time before he could qualify for
the reserved list, he improved his speed and was
Scouts, having received an
LYMAN
F.
BARRY
Whose
record as a Scout during the war and later shows a
keen interest and exceptional ability in radio. He is
now a Scoutmaster in charge of a New York troop
promoted from No. 345 to the second place on
the list in 1920. Then, at the College of the
City of New York, he served as secretary and
vice-president of the radio club, and experimented with several transmitters of spark and
continuous-wave types. For receiving, he has
built a three-circuit
honeycomb
coil
regenera-
tive set with a two-stage amplifier.
By authority of Colonel Holden, the
com-
Barry operated the
manding
U. S. Army station at Camp Devens, Mass.,
during the summer of 1920. Several times he
has kept Scout camps in touch with the world
officer,
Scout
when
his radio gave them their only prompt
communication. At the time of the Roma
disaster he gave the first news of it to citizens
of Geneseo, New York, where he had his set.
By 1922, he had passed an apprenticeship as
Assistant Scoutmaster, reached his twenty-first
birthday, and qualified as a Scoutmaster in
charge of a troop. The troop, No. 503 of
Manhattan, camped at Redding, Connecticut,
summer and for the first time in its history
this little hamlet was in immediate touch with
last
"
the world, through the Scouts' radio.
Reports
and the weather luckily agreed very nicely,"
reported Barry, "and we became quite believed
in during the two weeks we had camp there."
Radio Broadcast
278
made
West
trips to the
America, and Europe.
his
services
to
the
Panama, South
Between jobs he gave
Indies,
largest
Scout
news from
camp
in
parts of the
globe and transmitting headquarters traffic to
the local units.
When the public stampeded for the radiophone broadcasts a year ago, he was invited to
America, bringing
in
all
take a position which, had radio personnel
been more plentiful, would have been filled by
a man twice his years. A patent situation
developed that led to a quick change in the
management, and the Scout went to a radio
One day
store as a clerk behind the counter.
he discovered that he, like others who had been
connected with the manufacturing plant, was
under the surveillance of detectives acting on
behalf of a big radio corporation, whose rights
were alleged to have been infringed. He was
asked what he did when he discovered that he
"
was being watched,
got acquainted with the
detective and sold him a receiving set," he
I
answered.
Radio Amateur No. 4, Orin Livingston, and
No. 5, Howard J. Wendler, serve the Scout
troops in Roselle Park, New Jersey and go with
them to their summer camp. Both hold
amateur first grade licenses. No. 6 is Ralph
Woodruff, also a first-grade amateur operator,
who until recently worked his own and another
PUSH-CAR 1
Scout station at East St. Louis, 111.
No. 8 is a Brooklyn amateur, David Talianoff.
He is assistant scoutmaster and radio
"
"
His fist is well known
operator in Troop 97.
to amateur operators, for he transmits not only
SET
One
of these Kansas City Scouts
is pulling on a guy-rope fastened
to a mast made of scout poles
lashed together
At present, nine of his
Scouts have radio sets, four
of which are good tube sets.
Radio instruction and practown and on hikes are
tice in
Stoppart of the routine.
ping to rest under any convenient tree, they get a wire
aloft and are immediately
in contact with the world.
Radio Amateur No.
after serving in the
Council's scout
season,
cial
3,
B rookly n
camp
for a
became a commer-
operator
little
very
age age
while
still
above the averof
Scouts.
He
A RECEIVER THAT COST TWENTY-ONE CENTS
A
Scout
is
explaining
its
construction to the author
The Boy
Scout's Place in the Radio
Game
States.
It is heard in every state in the Union
and has been reported even from Hawaii,
He gives
France, England, and Germany.
much time
to handling the citizen messages
by the American Radio Relay League.
Three of these taken at random from a crowded
log book show delivery the same day they were
relayed
at such scattered points as Brooklyn,
Cleveland, and Robling, Ontario.
The ambition of the radio Scout is as different
from that of the technical radio amateur as the
job of the automobile racer is from that of the
filed,
rural postman and his flivver.
The technical
amateur is striving to get distance, the Scout
to give service.
When the technical amateur
has sent a message farther than any amateur
RADIO AMATEUR NO. 8
Assistant Scoutmaster David Talianoff at Niagara Falls
from
his
own
station,
2PF, but also from 2FP
at Brighton Beach, N. Y.
This station is said
to be one of the most efficient in the United
2FP,
Whose
ever sent one before he is satisfied for the
moment. When the radio Scout has picked
up and delivered in his community the information that it wants, he is satisfied until
he is needed again. He gets it from the nearest
Government station that broadcasts it because
that makes its reception most certain. The
technical amateur incidentally handles a good
many useful messages, and the radio Scout incidentally acquires a good deal of technical
When technical ability and the scout
ability.
spirit are found in one individual it makes a
very strong combination.
SOMETIMES USED BY TALIANOFF
well known to amateurs.
This station has been
heard in every State and far beyond the boundaries of the continent
"fist"
is
Radio Broadcast
280
In some places the radio training of Scouts
has been highly developed. At Donora, Pennsylvania, there is a Boy Scout Radio Experimental Unit composed of boys of Italian,
Finnish, Austrian, English, Slavish, German,
and Scotch parentage. In 1921 an Eagle Scout,
that is, one who has earned the highest award
for scoutcraft, visited the town and talked to
the Scouts about radio. Thirty-five of them
formed a class that night and those who had to
Dad before joining came in the next day.
From then on there was no rest for Deputy
Scout Commissioner McCune, who took charge
He took them to camp and
of the bunch.
ask
they studied electricity and magnetism. After
they returned home they did not give him a
chance to get a bath and shave before they
were asking when the first meeting would be
held there. They overflowed from his experimental station and the Commissioner had to
appeal to his Council for larger quarters.
Within a week the School Board granted the
use of a
room with
electric light,
running water,
The Scout Council appropri'neverything.
ated a hundred dollars for equipment. Work
benches, a store room, and lockers were built.
A
local plant donated sixty-five pounds of
magnet wire and a wood turning lathe. A
motor was installed to turn the lathe. Models
for
variometers,
variocouplers,
transformers,
and other apparatus were provided.
There
with a half hour of
three
as
and
times
much
theory
practice. Radio
books and magazines were always available.
The membership grew until there were 10
in the class.
When the public school closed
last June, day and night work had worn the
Commissioner to a frazzle. He did not admit
When
it until he was laid up for two months.
he recovered he organized the Unit with ten
were three
classes a week,
1
"
make every effort to secure them
members.
odd jobs of work," he reports, "and they always perform as Scouts should." He enrolled
in a well-known correspondence school which
granted him the privilege of permitting all his
Scouts to use the lessons and equipment that it
I
sent him.
In fourteen months this group has entertained three thousand visitors with radio concerts, from stations hundreds of miles away in
many
instances.
Rear Admiral H. J. Ziegemeier, U. S. N.,
Director of Naval Communications, recently
sent a message to the Boy Scouts of America
"covering the reasons why Boy Scouts should
be encouraged to receive regularly and distribute locally the broadcasts transmitted from
Naval radio
stations for the
"Your wonderful
public."
teaches you," he said, "that
happiness in
life
benefit
of the
organization
your greatest
comes from serving others.
In receiving and distributing the information
sent out by radio stations, you bring to others
TWELVE YEARS AGO!
4, 1911, shows ist Class Scout
Pickering and 2nd Class Scout Ziefman of Troop i,
Roslyn, L. I., operating a spark-coil set.
Compare this
picture with the frontispiece, showing modern apparatus
used by members of the same troop
This picture, taken July
information that your experience and observation teaches you means but one thing
greater happiness in life."
The Admiral's argument hits the bullseye.
But it is hard for an organization composed
largely of boys, and with less than one per cent,
of its official personnel on the salary list, to take
the initiative and bear the whole burden of a
service that will bring to a community daily
the up-to-the-minute information that it needs
and wants. The community should at least
ask for the service and encourage the Scouts
by thus letting them know that they are reckoned as an asset in the affairs of the public.
The Boy
There are other services
Scout's Place in the Radio
Game
281
for radio Scouts to
up and distributing
perform
weather forecasts, market reports, and other
The radio
Government code broadcasts.
horizon has been considerably broadened
within the past few months by the work of a
little-known inventor who is referred to above
as the President of the Cave Men's Club of
America. An expert in acoustics, he turned
besides picking
his attention
a year ago to the problem of
making radio a community feature as well as
a hobby for an individual and a pastime for a
household.
At his lodge in Waterford, Virginia, he
erected a seven-foot cement horn with a loudspeaker mechanism of his own design. With
of the ordinary types of tube receivers he
can bring in concerts, lectures and sermons so
that they can be heard at a distance of two
miles or more, yet with a mellowness that
makes it agreeable to hear them within his
any
own
No
printed advertising is necestunes in the show and his
audience assembles. There is little in Waterford to prevent their attendance at any time.
sary.
That
gates.
He merely
what he
thinking of the lack of
to
the
boys
busy, useful, and selfthings'
keep
is
is
respecting.
It is as plain as the stars
flag that the present
and
stripes
on our
situation in radio, plus
Scouts of America, gives
the status of the Boy
practically every American
community an op-
A VERY. LOUD SPEAKER
by Mr. M. C. Hopkins, President of the Cave
Men's Club of America, on his place in Waterford, Va.
Built
and whatever other broadcasting it may wish
to receive, and at the same time develop the
character of its boys by giving them useful
things to do.
All
it
needs
a
is
make radio
man who
service his
will
hobby
and an organization such as
the local government,
the
or
the Rotary Club to boost it.
Chamber
of
Commerce
Music and setting-up exercises in the public schools,
business information, news
from the ships at sea, diplomatic details from the capitals of the world
one is as
easy as the other when Boy
Scouts learn radio and use it
for the public good.
THE SCENE OF GREAT RADIO ACTIVITY
This is Station 8CQT, built and operated by the Boy
Scout Experimental Unit at Donora, Pennsylvania
portunity to organize a radio service that will
insure the receipt of all Government broadcasting, whether in code or by radio telephone,
February, 1923, brings
the Thirteenth Anniversary of the Boy Scouts of
America. Here's a wish
for many happy returns of
the occasion with an ever
to
increasing number of members ready
minister to their community and spread the
example
of unselfish service.
This Radio
Bill
We're Hearing About
By CHARLES H. KESLER
Member
of the
Bar of the District of Columbia and
HOUGH
associated with
closely
the radio industry for several years,
my" practical experience was slight.
became impressed
But last fall,
with the intensely human side of it,
as opposed to the radio of diagrams and
The boy next door had a set
technicalities.
A
1
1
which was perfect (having made it himself).
The boy was decidedly a radio bug. When he
insisted that
try his set,
placed the phones
to my ears, and instantly, through the ten-cent
was receiving the footcrystal (Woolworth),
It was then that
ball scores and cheers.
"
discovered
so many thousands had done
I
I
1
I
"as
me
is a great thing, that it
here to stay, and that, if there is any dissatisfaction with it, the causes of this dissatisfaction
could be and should be removed.
before
that radio
is
A new
law
is
being proposed for this very
was started on the bill some
Work
purpose.
In what foltime ago and is nearly finished.
lows, I am offering a few tentative suggestions
and pointing out certain features of the proposed legislation which may
on the bill and for the bill.
set
people working
The problem presents certain difficulties;
but none of them are insurmountable, and
they will be solved, with the help and suggesRadio must be built upon a rock,
tions of all.
for we cannot progress without firm foundations and without a goal which we are determined to reach. Our goal is the highest possible development of radio, and the foundation is
law, reasonable and just.
The new radio legislation, which has the
potentialities required,
is
designed to prevent
and to make broadcasting practical
service to all.
But just what is there
interference
and
of
in this
proposed
The proposed
bill
or this legislation?
is embodied in
House Bill H.R. 11964
introduced by Mr. White of Maine and the
Senate Bill 83694 introduced by Mr. Kellogg.
The House Bill was referred to the committee
on the Merchant Marine and Fisheries and the
Senate Bill to the Committee on Interstate
Commerce.
The proposed Radio Bill amends the present
two
radio legislation
identical bills: the
New York
Patent
Law
Association
radio laws as embodied in the Act of August 3,
Before the amendment can be under1912.
stood, what is being amended must be known.
Let us briefly consider the Acts now in force.
1
The earliest law now on the statute books is
the Act of June 24, 1910, as amended, which requires ships licensed to carry fifty or more pasThis Act
sengers, to have radio apparatus.
would remain in force under the new laws.
The spirit and purpose of the present laws is
well
summarized
the Secretary of
in regulations
Commerce
promulgated by
as follows:
"The
principal purpose of the regulation of radio
communication, international and national,
is to secure the greatest efficiency of maritime
communication through this agency, especially
means of promoting safety to life." The
as a
new law proposed extends the purpose to broadcasting.
The Act of 1912, which enlarges the scope of
the radio laws for the purpose of saving life, remains in force under the proposed legislation
with the exception of Sections i, 2 and 3 which
are replaced by others in the bill now pending,
and with the exception of Regulations three
and four of Section 4 relating to the use of a
"pure wave" and "sharp wave," which are
Certain other slight changes are also
repealed.
made in the regulations.
The regulations of Section 4 made by Congress are for the purpose of preventing or minimizing interference and to facilitate radio communication, but these may be waived by the
Secretary of
Commerce
at his discretion
when
no interference can ensue.
These regulations provide that every station
shall be required to "designate" a wavelength
as the normal sending and receiving waveEvery ship station, with
length of the station.
and every coast station open to
general public service must be prepared to use
two sending wavelengths, one of 300 meters
and one of 600 meters as required by the international convention in force, which convenWith exceptions,
tion is the law of the land.
exceptions,
all
stations
may
use other wavelengths.
At important seaports and where interference occurs between government stations and
This Radio
Bill
We're Hearing About
other stations, a division of time may be made
by the Secretary, the Government sending only
during the first fifteen minutes of each hour,
and other stations sending the remainder of
each hour.
Private stations not engaged in commercial
business or experimentation are limited, without special authority, under the regulations,
as amended to wavelengths between 50 meters
and 275 meters and to a transformer output
not exceeding one kilowatt. This applies
especially to amateurs.
No station not already in actual operation
shall be licensed for the transaction of commercial business by radio if within fifteen
nautical miles of the following govern1
Department
of
283
Commerce and
which transmit messages to vessels at sea or on
the Great Lakes or whose operation can interInfere with the exchange of such messages.
land stations are those which cannot transmit
such messages and which do not interfere with
such messages, depending on geographical position or range.
Both coast stations and inland stations are divided for the purpose of the
administration of the Act of 1912 as follows:
(i) Public service stations
(a)
ment stations: Arlington, Key West,
San Juan, Porto Rico, North Head
andTaloosh Island, Wash., San Diego,
(b) limited
general
(2)
Limited commercial stations
(3)
Experimental stations
Technical and training
(4)
"Sec. 6. That the expression 'radio communication' as used in this act means any sys-
amateur stations
(5)
Special
(6)
General amateur stations
(7)
Restricted amateur stations
All coast stations, except general and
restricted amateur stations, must be
able to transmit on the wavelengths
of
of 300 and 600 meters for the purpose
relaying distress signals. These are the
international
standard
maining types of stations,
wireless?
obvious.
The United States is a party to the London
Convention, but its provisions and regulations
apply only to stations on shipboard and to
coastal stations open to general public service.
This treaty, therefore, will not limit or prevent
effective legislation for the adequate control of
our domestic radio situation.
desiring to utilize radio
are enormous.
Certain of
interests
communication
these
involved in harmonizing the
difficulties
interests
are
now
recognized
by the
wavelengths
agreed
upon by treaty between the United States
and other nations. All coast stations are re-
tem of electrical communication by telegraphy
or telephony without the aid of any wire connecting the points from and at which the radiograms, signals, or other communications are
sent or received."
Will not this definition
soon become obsolete? What about wired
wireless?
Have not high-frequency oscillations
been transmitted over the network of wires and
rails connecting the Pacific with the Atlantic,
even without the knowledge of the Telephone
Company and Railroads, and without disturbDo we
ing the normal operation of their lines?
not plug in lighting circuits to receive these
messages? Is it not possible that it is wired
The
school
stations
Gal., or which may be established in
Alaska or in the Canal Zone. The
above are the main features of the
regulations which will remain in force
under the proposed legislation.
Section 6, which also remains in
force under the proposed legislation,
defines "radio communication" as follows:
various
are classified
Land staas ship stations and land stations.
tions are of two classes, coast stations and
Coast stations are stations
inland stations.
quired to listen in every 15 minutes on 600
meters to determine if any distress signals are
being sent. General public service is defined
as "paid business" conducted on commercial
wavelengths between ship and shore, or between
ship and ship.
Limited public service is "paid business" between certain designated land stations, ships
or line of ships.
Limited commercial stations are not open to
public service and are licensed for a specific
commercial purpose. The nature of the reit is
believed, will be
The
interests or classes interested in radio
be additionally or differently classified as
may
follows:
(1)
The Federal Government (Army, Navy,
Commerce,
etc.),
The
large class of persons interested in
broadcast reception and using receivers,
(3) Manufacturers and dealers (including
(2)
the big fellow and the
little fellow),
Broadcasting agencies, and
(5) General public.
(4)
Radio Broadcast
284
judge on the matter of granting licenses. No
appeal to a court is possible. A writ of mandamus cannot be issued to compel the Secretary
Under the law
to grant or renew a license.
now in force the applicant can have his day in
Whether or not it is necessary to give
court.
How are these various interests to be brought
into cooperation on the principle of live and let
live?
The public is interested, because, if the
radio industry is not in a healthy condition, it
affects
all, it
A
lowers the genera. prosperity.
1
system of broadcasting which
apprt?.
xirnates tne
means that people will want sets J n in ~
creasing numbers.
That means greater^11"
joyment, more business, a more
satisfactory
the Secretary this autocratic power to control
broadcasting properly am not prepared to say.
At least the matter should be thoroughly con-
ideal
state of affairs
1
for
the people as
a
whole
he enactment of suitable
legislation to ap-
proach this ideal condition, even
though
mains an ideal, should receive the
operation of
it
re-
and yet of such character that
injustice cannot be done
by officers in
executing the law. The law should
operate automatically as far as
possible, considering the volume of
details
which cannot be covered other
than generally
by law.
The only proper
authority
for
controlling
the radio situation is the
Federal Government
But within the Government
are various interests, the Army,
Commerce
c
?
^red before passing the
bill,
sioiis .
be admitted that such authority if
rinr
Hsed will be beneficial, yet to favor
u
rightly exeroe 24
tura
The granting of a
ones friends is Tito. the
proposed act and
station license undef a PP^;
of the
S cretion"
its
he
renewal is "in the
'"- "c!,
JTi
has operated
Ild.b
UJJCIdlCU
c
ese '- t en
Secretary.
Certainly if a persoir
years,
ul at
a station
satisfactorily for
^ not be
he should have his
|>\
hk renewal
r^n^M/n] ^ n '^
i-,-ai
IIU
dependent upon the whim
riiiiuui
or politli
LJUI1 l
motive of the
Secretary. The
t
,
,
hearty co-
the people and of their
representatives in Congress.
Obviously any law that flexibly covers the
situation and takes care of all
classes
must be more or less
general in terms
all
1
"
L
^
'
'
'
.
1
grant-
ing of original licenses must
depend on
the facts in the
case, whether or not
there will be interference.
all
here there
But even
the possibility of favoritism
and
no recourse to a court is
possible
Section 2C provides that the
Secretary mav
grant a license only to a station
which is in
the interest of the
"General Public Service"
A better expression could be used
here in view
its
acquired meaning, referring to a commeris
Navy,
and other
departments. There will
always be more or
less friction between
these several departments
cial station
as long as one of them is
sending messages for pay as deplaced in control
It
fined above.
is as if one of the
Construing this clause one way
parties to litigation acted as
would rule out amateur stations.
Yet the best possible
judge.
broadcasting
Section iC provides that
system can be worked out
government staonly with the coUSCd exclusivelv for
operation of these several
communication
ffr
"f u
departments.
IticiaJ business are
Ihe logical control
subject to control by the
would be a superSecretary of Commerce and licenses are redepartmental control by the President or
his
quired.
Government stations used exclusively
representative.
The new bill places the con- tor
official business shall use
trol in the hands of
such wavelengths
the Secretary of Commerce
as are
assigned by the President.
with one exception-the
FurtherPresident is authormore, they must observe "such
ized to
regulations"
assign wavelengths to the
and
as the
Army
Secretary of Commerce "may" (why
Of course.we
Navy
might do well to have
not "shall"?) make to
prevent undue interadl
just as we have had a
ference.
These regulations can be
n
t
P ?
Director
off Railroads,
suspended
etc., but the
Secretary
by the President in time of war. This is
Commerce has in the past controlled
all
the
very good and shows that the officers of the
situation and as the head of
the Department of
Army and Navy who were on the committee
Commerce, the matter comes
very properly
which framed this bill are for
under his supervision.
doing everything
they can to further the cause.
The proposed bill is, like
Certainly if
most original bills,
there is any point to be cleared
indefinite and inaccurate in
it can be
up
places-but it is
taken care of to the satisfaction
m
f
general,
a re
At
good
least, all interests are
securin g the best
possible
bro,T
,
broadcasting conditions.
Wh
le
!
.
The Secretary under the new
bill is
the final
of a great
majority of the people.
The proposed law is also more
stringent in
egard to aliens.
Under the present law citizens or domestic
corporations can secure sta-
This Radio
Bill
We're Hearing About
Under the proposed law even a
tion licenses.
domestic corporation cannot secure a license
if one alien be a director or officer or if a fifth
of the capital stock having voting power be
There is grave
controlled by aliens.
doubt as to the wisdom of or necessity for such
If there must be restriction as to
restrictions.
owned or
domestic corporation, it should be based
on whether or not the
The printed record in the famous
poly, it is.
anti-trust cases would put the five-foot library
of Doctor Eliot to shame, but with all the
voluminous records before them, courts differ
to whether an organization is a monopoly or
not. They even differ as to what a monopoly is.
a.s
They may be
lawful, such as a patent
corporation
controlled by
poly.
Keep Your Eyes Open!
in fact
Following a report that the radio legislation, prepared as a result of the Conference
called by Mr. Hoover last February, had been
"pigeon-holed," RADIO BROADCAST invited all
the editors of radio publications in the Metropolitan District to attend a conference to
decide upon a definite form of action to relieve
the jam existing in the ether. This meeting
took place November 6th, last, and was followed by a similar meeting in Pittsburgh, Pa.
aliens.
Certainly one alien director does not necessarily control a corporation nor does merely
a fifth of the stock.
Section 2C is as
follows:
"The Secretary of
Commerce is hereby
The fact that legislation was essential and
urgently needed was recognized by all, and a
resolution was passed at both meetings to get
the proposed bills out in the open and through
the necessary legal channels.
Cognizance was taken of the weak points in
the proposed bills but no time was lost in attempting to weed out the objections that
authorized to refuse a
license to
.
.
any person
which, in the judgof the Secretary,
monopolizing or
.
ment
is
seeking to monopolize
radio communication,
directly or indirectly,
was
the manufacture or
or
apparatus
by any other means.
The granting
of a
li-
cense shall not estop
the United Statesfrom
.
However,
.
this
Commerce
it
is
essential
in
altering
any
legislation to be certain that the new is not
even worse than the old for it is possible for
laws, in the hands of artful lawyers, to be dis-
against monopolies or
restraint of trade."
1
of
naires.
prosecuting seich person
for a violation of the law
.
you to do.
has prepared data of a technical nature, derived from questionnaires sent to all branches
of the radio industry and other organizations
have done likewise. It is quite likely that
the technical aspects of the new legislation
will be satisfactory to most of us, if due consideration is given the conclusions arrived at
after a comprehensive study of such question-
through the control of
sale of radio
left for
The National Radio Chamber
torted beyond recognition and
know why
clause was made
don't
made
to defeat
own purpose. We must have some relief
from existing conditions, but we must be sure
that the relief is not temporary, to be followed
by a relapse into some worse malady. THE
EDITOR.
their
a part of the bill.
At any rate the authority given here
unnecessary as the
Secretary can refuse a
is
license, "in his discretion," for
soever.
The whole
fundamental
scheme
is
is
final.
is opposed to our
government which
judicial and executive
thing
of
separates the legislative,
Here the
departments.
merce
any cause what-
of
Com-
Secretary
the judge.
His judgment (or opinion)
If he thinks a company is a mono-
ever,
mono-
the Secretary
going to try the case
before passing judg-
a
is
285
I
s
And as a climax to show how right
ment?
the Secretary's judgment might be, the
granting of a license
is not to estop the
gov-
ernment from bringing
suit under the Acts
provided for that purpose, putting the poor
monopoly to further
expense!
Why
not
let
the courts pass on
monopolies and the
Secretary on licenses.
Unlawful
monopolies
are bad, but certainly
this clause does not
remedy matters.
Adequate provision
also made to enable
the Secretary to revoke
a station license whenever the owner of the
is
fails to obey
the law or any regulation or "whenever the
station
Secretary of Commerce shall deem such
revocation to be in the
public interest." The
clause quoted is broad
enough to allow the
Secretary to revoke
the license for almost
any reason. The licensee or owner may
have a hearing, howon the matter of such revocation, but only
before the Secretary.
Other clauses of the
of operators' licenses
bill
regulate the granting
and
their control.
No
can be granted a license nor any repreManufacsentative of a foreign government.
turers and importers of radio apparatus should
alien
Radio Broadcast
286
vise the parts of the bill relating to restrictions
aliens.
For instance, under Section 28, a
"representative" of an alien or of a foreign
obtained fraudulently and to impose penalties
government cannot be granted a station license
even though an American citizen or an AmerWhat does "reican controlled corporation.
license.
on
presentative"
mean?
What
does
it
cover?
While these restrictions are apparently war
measures they do tend to restrict importation
These restrictions of
of foreign apparatus.
the proposed bill should be given full consideraLet the light of day shine
tion at the hearings.
upon them.
Under Section
for
of regulations in cases where
have been granted or to revoke the
violation
licenses
have merely touched on points of the bill
which to me seem to need revision or amplification.
It is believed that the bill will meet
the recent phase of radio communication, that
is, broadcasting, which must however remain
I
subordinated to the use of radio for safeguarding or saving lives at sea.
The committee whose conferences resulted
in this bill
4, a permit is required to start
the construction of a station. This does not
apply, however, to amateur stations and government stations used exclusively for official
If the station is not constructed
business.
have done their work
well.
It
may
be advisable to incorporate in the act other of
their
recommendations made
in their report,
as
prohibiting point to
point radio communication, direct advertising,
etc., instead of leaving it to regulation by the
for
such,
instance,
within the time specified in the application for
permit, the latter is automatically forfeited.
don't know.
Nor
Why this is necessary
does the granting of a permit oblige the
Secretary to grant a license after the station is
Build the station first, and then take
finished.
Secretary.
a chance on securing a license
Section 5 provides for an advisory committee, acting as advisors for the Secretary.
It is suggested that one of the matters on which
money
committee should report is broadcasting.
is to comprise twelve members,
six from the government departments and six
non-government members of "recognized attainment in radio communication," to be appointed by the Secretary.
It is believed that, if any prohibitions are
necessary, the law should positively so provide.
While certain foreign countries now prohibit
the use of such receivers, the enactment of
1
!
this
The committee
Section 8 permits the Secretary of
Com-
merce to impose a penalty for perjury! Even
though this section be constitutional, it seems
to me that the use of a transmitter without a
license should be made a misdemeanor, the
court having jurisdiction of such cases as well
as of perjury.
Of course, the Secretary should
be able to revoke a permit or license when
The Bureau of Standards should be empowered to make a complete study of the radio
situation in all aspects.
This can be done by
suitable appropriation and enlargement of
authority by Congress, if such power and
are
now
lacking.
This committee also recommended that the
Secretary be empowered to prohibit the use of
receivers which cause the radiation of energy.
such a law would render useless important and
valuable patents as well as thousands of sets
now in use, unless it should exempt sets now
in use.
There, then, is the bill a bill to put across
even with its defects. This act is the foundation on which the future of radio broadcasting
will depend.
Lvery one of us should get back
of
it,
offer suggestions,
get busy!
and push
it
hard.
Let's
The Facts About
By
the invention of the
BEFORE
necessary to use
most
use were
sitive device in its
this
vacuum
sen-
highly
way, as the
efficient
detectors in
inefficient, to say the
least.
In Search of a
With the coming
the
vacuum
of
There
tube,
speaker,
however, the situation
became entirely
ent.
human
Infinitesimal vol-
may now
fitting
is
illustrated in Fig.
Loud Speaker
be
no such thing as a perfect loud
any more than there is a perfect
Science, however,
is
amplified to the point
even better music than the phonograph
they can be
used to operate a relay
there are a great number of loud speakers
capable of no speech whatever. Makeshift
where
if
speakers, like makeshift shells, are
There is plenty of room for
usually "duds."
in this interesting field.
In this article, Mr. Allen tells something of
the difficulties to be overcome, the present
development
With the development
the vacuum tube
methods in general use and the hope of an
early solution to the problem.
Following, as
it
does, "How Your Telephones Work,"
of
came
broadcasting,
and the novice soon
outgrew the limitations of the head set.
The owner of the radio
which appeared
in
our January number, rhis
article should be of especial value to those of
our readers whose interest in sound reproduc-
tion has induced
difficulties
no longer
typified only by the
boy amateur intent on
receiver
is
met
them to
in
enthusiast.
surmount the
loud speaker design.
home owner as well, is
The present-day novice
wants concerts and educational programmes so
that they are audible to the entire family
without the necessity of wearing head sets.
Thus has come the loud speaker and with it
the emancipation of broadcast reception.
Early attempts at loud-speaker design were
confined to attaching standard head telephone
One of the
receivers to horns of various kinds.
earliest was the application of a telephone re-
The reproducer was
ceiver to a phonograph.
removed and by a special fitting, the receiver
was attached to the tone arm, thus affording
the desirable characteristics of the phonograph tone chamber. The receiver with its
all
try to
THE
EDITOR,
getting distance; for
the business man the
now an
but
loud
necessary, so that the
extreme sensitivity of
the telephone receiver
is no longer essential.
.
ing
is
being.
i
Another attempt
along the same general lines was to provide a
horn with one or two openings at its smaller
end to which the head set was clamped.
While the art was in its infancy, the quality
of transmission was poor, and such makeshifts
were endured. As the
quality of broadcast-
ever trying
to improve existing conditions and the loud
speaker is receiving a great deal of attention.
There are some loud speakers, designed by
acoustic and electrical experts, that produce
differ-
tages received on the
antenna
ALLEN
G. Y.
tube, the telephone head set was
the universal device for recognizing
radio signals. At that time it was
Loud Speaker
the
improved,
how-
ever, two outstanding
defects were noted.
The quality was far
from that heard on a
head set and the amplitude was not enough
Al-
for all purposes.
most
all
developments
loud speakers in the
past year have been
along the lines of improving the quality
and quantity of the
received signals.
To have a loud
in
speaker faithfully reproduce sounds is one
of the most complex
problems facing the
manufacturers
day.
to-
There are any
number
of
loud
speakers on the market, but it is generally
admitted that none of
them has yet attained
perfection.
loud speaker functions in two distinct
First, it must take the electrical imways.
pulses delivered to it by the vacuum tube and
convert them into mechanical motion, then
this mechanical motion must be transformed
into air waves.
Neither the electrical system
nor the acoustic system can be designed separately, but both must be developed together.
One aim in the design of the electrical part
of the loud speaker is to get the diaphragm to
vibrate with the same amplitude at all musical
frequencies that may be used for the same
applied voltage to the terminals of the loud
The ear is capable of hearing about
speaker.
eleven octaves, and the range of musical
Any
Radio Broadcast
288
sounds runs from about 40 vibrations per
second up to about 4000. The range of the
human voice extends from about 60 for low
bass notes to about 1300. A good loud
speaker, therefore, must cover these ranges
without distortion.
The point of first importance is to insure that
the forces acting on the diaphragm faithfully
reproduce in air waves the variations in curTo
rent that come to the loud speaker.
of
the
electrical
this
end,
designers
accomplish
mechanism must be governed
by certain physical
number of turns in the space available,
the wire must be very small in diameter, which
means that the electrical resistance of the
large
winding
is
high.
and
is
shown in Fig. 2. To the poles
permanent magnet are
attached two soft iron pole
pieces on which the coils are
wound. Supported very close
of a
to
the pole pieces
touching them
diaphragm.
FIG.
is
well
designed
loud
PERMANENI
"MAGNET
laws.
speaker receiver mechanism
is similar to that of a standard
receiver
a
DIAPHRAGM
SUPPORT
A conventional loud
telephone
In
but not
the
iron
I
Telephone receiver designed to
fit over phonograph tone arm
FIG. 2
speaker, therefore, the resistance of the winding is a measure of the "current sensitivity"
of the instrument.
In radio, the loud speaker is generally connected in series with the plate of an amplifier
tube as shown in Fig. 3. For loudest response, the alternating voltage or pressure
caused by the incoming signal should be the
same between the plate and filament of the
vacuum tube as across the terminals of the loud
This condition cannot be comspeaker.
pletely met as the voltage across the loud
speaker varies with the voice frequency whereas
the voltage across the tube remains nearly
It is cusconstant regardless of frequency.
tomary to make the voltages approximately
equal at some voice frequency such as 500 or
800 cycles per second.
As the voltage depends upon the "resistance" or "impedance" of the tube and loud
When
a variable current is sent through the
the pull or attraction of the pole
pieces for the diaphragm varies, thus allowing
the diaphragm to vibrate.
It should vibrate
with an amplitude proportional to the current
winding,
strength.
To
is
THIS
FOR LOJDEST RESPONSE
y
BATTERY
insure this, the length of the
gap must be small which, therefore, limits
the amplitude of vibration, and thus the volume
of the loud speaker, by the diaphragm coming
into contact with the soft iron pole pieces.
air
A
THIS A.C. VOLTAGE
--SHOULD EQUAL
loud speaker constructed as shown in Fig. 2
therefore limited as to the volume it can
produce.
Now the variation in pull on the diaphragm
depends on the variation in current in the
winding and also on the number of turns of
As the currents used at the radio rewire.
ceiver are very minute, very many turns of
wire are needed on each bobbin. To get a
FIG.
3
speaker, the impedance of the loud speaker is
generally made equivalent to that of the tube.
Standard tubes have an impedance of about
20,000 ohms, and loud speakers should have
an impedance of about this value at 500 to 800
cycles for maximum volume.
Sometimes it is more convenient to wind
In this
loud speakers to a lower impedance.
case, a transformer must be interposed between
the plate circuit of the tube as shown in Fig.
This transformer has the larger number
4.
The Facts About the Loud Speaker
of turns connected
in
and the lower number
series with the plate
of turns connected to
the loud speaker.
One very important
in the design of the
feature to guard against
mechanical part of a loud
289
and try variety, and the human ear
has in most instances been the means by which
the quality of the different designs was measured.
Now, it is extremely difficult to get two
people, when listening to a loud speaker, to
of the cut
It is
agree on fine differentiations in quality.
an interesting fact that many people prefer a
loud speaker which apparently distorts somewhat. Loud speakers that throttle the acid
quality of a musical production and accentuate
the string and wood wind instruments seem, to
be preferred, and yet such loud speakers will
FIG.
4
is
mechanical resonance. All mechanical systems have a natural period of vibration, and if they are subjected to vibration
forces of this period or frequency, they will
speaker
respond with an amplitude far out of proportion to the applied force.
Fig. 5 shows graphically how a loud speaker
diaphragm would respond to a range of fre-
quencies including its own resonant frequency.
In such a test, the voltage across the loud
speaker or the current would be maintained
constant.
A loud speaker designed with a
moving system whose natural period fell
within the range of voice frequencies would
distort horribly and would be practically worthless.
All well designed loud speakers, therefore, aim to have the natural period of the dia-
show obvious distortion on speech. In short,
the successful design of a loud speaker is a
most involved problem which has barely been
touched as yet.
was early discovered that the material
It
from which the horn was made had an imIt was found
portant bearing on the quality.
necessary to make metal horns from dead
metals such as zinc, lead or cast aluminum.
Horns made from wood and wood fibre, cellu-
FIG. 6
The loud-speaking
unit
which uses
adjustable magnet
system
of a device
an
-
phragm and moving system
range of the
ments.
human
well above the
voice or musical instru-
the electrical
of a loud speaker
Although
design
simple
and
mechanical
is involved,' it is
to the design of the
chambers.
In spite of the
when compared
horn and sound
loid,
hard rubber and such non-metallic ma-
a very pleasing quality to music,
cannot be said that they do not distort.
It has been found that the horn must be
adapted to the particular loud speaker and a
horn that would give good results with one
mechanism may be totally unsuited for anterials give
but
it
other.
Loud speaker development has progressed
along two distinct lines. One type has been
similar to. the conventional telephone receiver
in construction in that the
diaphragm, made
from iron, is subjected to the magnetic force
and also sets the air in motion. In the other
type, the diaphragm is mechanically attached
to an iron vane on which the magnetic forces
large number of loud speakers now on the
market, it is pretty generally acknowledged
that a very large amount of research work
must yet be done before a loud speaker that
absolutely distortionless is evolved.
Most of the development work on loud
speaker horns and sound chambers have been
is
act.
air
The diaphragm
waves
One
in
motion
serves only to set the
in this case.
loud speaker of the
first
type
is
es-
sentially an aluminum casting, into the base
of which are screwed two telephone receivers
of the same type that are used in the head set
manufactured by the same company. Such a
Radio Broadcast
loud speaker is limited as to volume but will
give sufficient sound intensity for a small room,
when used with a two-step amplifier. Another
loud speaker of the first type uses no per-
manent magnet.
ever,
is
which
adjustable
in the
centre of the pole pieces in such a way that it
can oscillate within limits. Surrounding the
armature and supported by the pole pieces
is
The magnet system, howby means of a threaded nut,
complete loud speaker
is
operated
FIG.
9
the coil, consisting of a large number of turns
of very fine wire.
The armature has attached
to it at one end a small rod mechanically conFIG.
7
to the corrugated diaphragm.
current is connected to the coil
through lead wire L, one end of the coil is
instantaneously north and the other end is
south.
An inspection of the sketch will show
it
necting
Mechanism
of a loud speaker which
has a lever attached firmly to the diaphragm and actuated by the magnet
from the outside
of the box.
In this way
considerable control of the volume and quality
is obtained.
Fig. 6 shows the loud speaking
unit of this device.
To
permit of greater amplitude in the motion
diaphragm and still maintain a small air
gap, various lever systems have been introduced into loud speaker designs from time to
time with varying success. The danger arising from such a procedure of course is the
introduction of distortion.
There is the possibility of increasing the
weight of the moving
system to the point where
it will be objectionable
and also the air resistance
may reach such a point
as to interfere with rapid
motion.
Furthermore,
great rigidity in the movof the
When
a
that this form of field will add to the flux on
one side of the armature and subtract from it
on the other side on both ends of the armature.
This will cause the armature to tend to rotate
about pivot Q, thus displacing the diaphragm.
A
the current will cause a disthe
placement
opposite direction.
As will be noted from the sketch, the distance from the diaphragm rod to the pivot is
reversal
of
in
INPUT
FIELD
ing system is essential
or the loud speaker will
MIL
FIG.
IO
"rattle."
Fig. 7
interior
illustrates the
mechanism
of
one type of lever action
loud speaker that has
proved highly successful.
M
is
a
permanent
magnet provided with
two soft-iron pole pieces
P and P 2 Suspended
1
.
between the poles of
magnet
FIG.
The horn
is
8
non-metallic
is
a
this
soft-iron
armature, A. A is pivoted at its centre in the
about twice that from the middle of the pole
For any motion of
piece to the same pivot.
the armature in the air gap, therefore, the motion of the diaphragm will be about twice as
Great volume can thus be obtained
great.
from a loud speaker of this construction and
distortion can be kept at a minimum.
Fig. 8 shows the loud speaker complete with
a non-metallic horn. This horn is especially
designed to produce the minimum of distortion
and the metallic quality is, of course, entirely
lacking.
The
internal construction of another loud
The Facts About the Loud Speaker
speaker of the same principle is shown in Fig.
Here the armature is affected only on one
9.
side by the magnetic flux, and its movement
must be kept down to a very small amount to
maintain the length of the air gap small. A
long lever is thus necessary to obtain sufficient
displacement of the diaphragm.
This particular instrument is provided with
a mica diaphragm which combines great flexiIt is mounted on a
bility with lightness.
stand in such a way that it can be rotated in
any
direction.
A
loud speaker of a design differing from any
of these mentioned is sketched diagrammatically in Fig. 10. In this case, no iron diaphragm
or armature is used.
Instead, there is attached
to the diaphragm a coil that vibrates with the
This coil is connected to the
diaphragm.
source
and vibrates in the field of
energizing
an electromagnet, M. This magnet is energized from a 6-volt direct current source.
This construction gets away from a direct
cuit will
291
give good
results in the
home
where
it
to
but a small
fill
is
desired
There are
however,
room.
cases,
where more volume
is
desired.
at times
it
\
In fact,
is desired
make music and
speech audible to
to
crowds of people assembled in the open
air.
The power
avail-
able from a two-stage
amplifier becomes
totally
in
inadequate
such cases.
To get the
sary
large
neces-
amplitude
volumes,
for
it
is
FIG.
12
instrument being limited in its
amplitude of vibration by the length of the air
In fact, it is claimed that practically any
gap.
volume may be obtained from this instrument.
necessary to use additional stages of amplification with tubes that
are capable of delivering very much more power
than can be obtained from an ordinary receivThe use of these tubes entails high
ing tube.
A
plate voltages
operating
photograph of
this loud
speaker
is
shown
in
Fig. 12.
In general, good operation of a loud speaker
at moderate volumes may be obtained by con-
necting
last
it
directly in the plate circuit of the
tube of a two-stage amplifier.
This
cir-
and heavy consumption
of
B
battery energy. The resulting volume, however, is remarkable.
Speech and music have
been made easily audible over distances of
more than a mile.
Fig. 1 1 illustrates an amplifier designed for
use with the loud speaker shown in Fig. 8.
It consists of two stages, using three tubes.
The tubes are capable of delivering considerable power and the last two are connected
in such a way that the loud speaker is supplied
with the sum of their outputs.
The plate circuits of the last two tubes are
connected to a transformer having a split
primary and the sum of their effects is impressed by transformer action on the secondary
which is connected to the loud speaker unit.
In conclusion, it might be said that the manufacturers of loud-speaking devices have ac-
FIG.
An
I
I
amplifier designed for loud speaker use
complished wonderful results when the time
they have been working on them is taken into
The problem is extremely inconsideration.
volved; but we cannot doubt that before long
vast improvements will be made and that we
shall see the day when broadcasted material
can be made audible in practically any volume
without distortion.
DONALD WILHELM
By
visible
from
all
for miles around, there are
directions
now three
glowing atop the Arlington
Towers, one six hundred feet up,
the others four hundred feet up
from the hill that looms above the Potomac
overlooking Washington. The towers of NAA,
lights
ANIGHT,
for
lights, now constitute a landmark
the aviator, signifying that he should bear off a
bit southeast, or swing over the Washington
Monument, the Capitol and the Navy Yard,
and these
and that Boiling Field is underneath. With
the coming of planes and of radio, what a
changed aspect this Arlington hill has taken on
since George Washington and Major L' Enfant
stood there, as tradition has it, and planned the
city of
Not
Washington!
so long ago,
when an amateur
vention was about to assemble
in
radio con-
Washington,
more than three hundred of its delegates were
asked what landmarks they desired most to see
in and about the Capitol: should the Capitol
come first, or the White House, or should it be
NAA? Back came the post-card replies, almost unanimous for NAA. The giant on the
hill has a distinct personality, and has long
immensely popular with thousands of
It
has had some great exacquaintances.
been
In February, 1920, for inperiences, too.
stance, there was that memorable snow and
sleet storm that for whole days tied up nearly
every railway wheel on nearly every railroad
up and down the Atlantic Coast. It concen"Our antenna then contrated on Arlington.
sisted," said Charles Range, who is still in
"
charge of the station's crew of six men, of three
wings, triangular in shape, each consisting of
two spreaders eighty-eight feet long and each
weighing 3,000 pounds. There were twentythree wires in each wing, there was ice eight
inches in circumference on each wire eleven
tons of ice on each wing, thirty-three tons altogether,
if
you figured
it
out, after that sixty-
Well, the evening
about
7:30, there were
7,
1920,
three reports that sounded like a battleship
coming on the range the first sounded like a
three-inch gun, when the shackle in one of the
mile gale did
of
its
darnedest.
February
insulators gave way, the next
was a 4-inch gun,
1
when one end
of the antenna parted from the
big tower, and the last sounded like the explosion of the whole works, when that debris
itself in the frozen ground."
But the point in all this is, not that the station kept working for two days before the last
wing crashed, but that, during the ensuing six
days, mariners, jewelers, farmers, amateurs
and others, by radio, by telegram, by letter,
and in sundry other ways, transmitted one
long wail to the Navy: "What in the world has
become of our old friend, NAA?"
And there were others who addressed themselves to the Secretary of the Navy, and to their
and Senators, about like this:
Congressmen
"
Save money if you have to, but for heaven's
sake give us back NAA!"
buried
NAA has a bigger circle of friends in fact
If service renthan any gentleman we know.
dered is immortality, in radio history this
as
station will always be what it is to-day
much a landmark and institution as almost
anything east or west of the Potomac.
NAA has given more service to more agencies
and people and to the progress of radio itself
than any other station. One can safely go
further and say that its original loo-KW
Fessenden spark set, which now seems as ponderous and noisy as a steam shovel, has given
more service than any other set in existence.
It is still hard at work, with its heavy rotor and
forty-eight
people
this
It is still
who
are equipped only with crystal reYet, progress in radio is so rapid that
ceivers.
and
not much the
serving hundreds of
glistening tractors
worse for wear.
much-celebrated
belt
many more
which
set
with
is
likely to
years,
and there
drive
its
2OO-hp motor
be retired before
is
a
movement on
foot,
loyal devotees of radio will join,
to set this old fellow up in the National Museum for the benefit of posterity, with an inscription about like this: "Here lies the original set
From Februin the first high-power station.
tube
sets
until
arc
and
supplanted
ary 13, 1913,
it, it was a good neighbor and a friend in need
all
to hundreds of thousands."
NAA, remember, was
the
first
stations
of the
Navy's
that
chain
Private
chain
of
which,
when combined with American
high-power
N..-A
Enterprise, Inc., absorbed links from Germany's supreme chain, links from Britain's imperial chain, and in less than a decade gave
America the world's radio supremacy and a
more effective guardian of such international
understanding and peace as is possible these
days than any other agency on earth.
It was from NAA that the human voice first
leaped the Atlantic. Very early in that morning of October 22, 1915,3 little group of Naval
officers and others were routed out of bed to
be told that they might hasten to Arlington and
from there talk to other Americans in the Eiffel
Tower, with the bustle and roar of a thousand
guns only a few miles away from Paris and the
Tower itself used as a target now and then in
the daytime.
They talked, and were heard in
France and at Pearl Harbor, in the Hawaiian
Islands at the other side of the world.
an epic
in itself
how American
There's
Enterprise,
A
293
Inc., perfectly confident that we would have to
enter the war, went secretly to the Navy in
1914, explained that it wanted to lend a hand to
the Navy by developing the radiophone with
the help of such facilities as the Navy alone
could offer, and how, with the Navy, it put-up
a wooden shack beneath
NAA's
big towers,
went to work, and came through, that October
morning.
was
on September 29,
Mr. Vail speaking,
was first transmitted from New York to the
Mare Island Navy Yard on the Pacific Coast,
It
via Arlington, too,
1915, that the
human
voice,
NAA,
then via ether westward.
broadcasted a President's voice, and it has been NAA that has
enjoyed all sorts of similar but less important
When the argument, spark vs.
distinctions.
continuous wave, was raging, and the Navy
wanted only the better system for the rest of its
via land wire to
It
was
THE BEST KNOWN RADIO STATION
NAA
IN
that
first
THE WORLD
Arlington, Virginia, whose distinctive spark note is heard every noon and evening by thousands of people, both afloat and ashore, who tune in to keep posted on the time, news, and weather
NAA,
Radio Broadcast
294
NAA
that served at the land end
chain, it was
while a cruiser, the Salem, moved eastward
toward Gibraltar with experts on board, testing
out both systems. And now, at the end of a
period of not quite ten years, the same station
is making experiments with tube sets, with the
result, perhaps, that before long the Navy will
be satisfied that even NAA's C.W. sets are
destined for the National Museum.
Some years ago, the question arose as to
whether a big and a little set could be worked
at
simultaneously without the big one
out
the little one. There were those
burning
who declared it couldn't be done. It was
Commander Hooper, as the story goes, who was
one of those who said: "Let's try."
So, it seems, suiting the action to the
word, he pressed the keys of both sets
NAA
at once,
and nothing disastrous
happened.
Again, in 1915, authorities doubted
whether the Navy Department,
hardly more than half a mile from
NAA, could receive with an antenna atop its own building while NAA was
the flag-pole of the State,
War and Navy Building an antenna was run,
That
with a wire down to the telegraph room.
worked. Now there is no receiving at
and no gob hammering a key either receiving
is done via a 5-wire antenna strung half the
length of the new Navy Building just over the
Potomac from NAA's big hill, and sending is
done from a booth on the top floor of that buildby reing, by land wire and automatic key
mote control, in other words. That's why, in the
brick building hard by, but still entirely separate from the main radio building at NAA, you
find two rooms, having doors half a foot thick
with soundproofing and walls quite as thick,
of which the doors are no longer closed.
And
that's why, in the smaller of these rooms, on a
narrow shelf fastened to the wall, you see eight
keys in a row and likely as not a couple of them
working automatically, while perhaps the
spark set next door is snapping or the C.W. or
tube sets work in the adjoining building with
nary a sound except the low hum of motors.
transmitting.
after you've climbed NAA's big hill
at the neat brick buildings
and looked about
faced with limestone, at the towers rising high
above you, at the fine lawn and flower gardens,
at the wonderful view of Washington, and at
other interesting things in and about the station (it cost originally only $300,000, by the
is
maintained with a crew of
six
men
and what happened. It dawns on you how
fine a site it has
and that means a lot. You
realize that there are no mountains, hills or big
buildings anywhere near to divert or absorb
NAA
You realize that
is
energy.
inland
to
be
safe
from
enough
fairly
any
attack except that of enemy aircraft, which
electrical
far
might more
likely make the Capitol itself the
see that the site adjoins
Fort
You
target.
Myer; that there are ample sources
of outside
power; that the place, with screen protectors
about the base of the towers and barb-wire
entanglements all about its 16^ acres
was, with a guard of marines on
duty, safe enough from even pro"
But did anything
enemy fanatics.
want
to know.
happen?" you
"Nothing much."
"Well, what?"
"Well," your informant confesses
at last, "not a doggone thing hap-
pened except one night."
"Then what?"
Up
NAA
Now,
way, and
at a cost of only $18,000 a year), you wonder
how they guarded this station during the war,
"O
You
nothing!
see
we had
the
wire
entanglements
charged with just enough
current to hold anybody that touched them.
all
That particular
night, a society flapper that
took a fancy to one of the Marines, and can't
see that, tried to climb over, and he tried to
I
her.
The searchlight picked up this
romantic picture, the guard stopped the yells,
and the flapper was sent home to mother!"
But there are other things you want to know,
all in short space, about this giant and what
help
it
means
to the
Navy and
the nation.
The
ground system is particularly interesting. It
is a checkerboard of wires buried from 14 inches
two
extending over the entire 3! acres
All of these wires
At one side of the
reservation they terminate at a running brook
and all are brought together at two sides of the
to
feet,
1
of the original reservation.
are bonded at crossings.
transmitting building.
Above this checkerboard, resting on blocks
of Vermont marble, with the ground switches
evident enough, rise the three towers with
their 1050 tons of steel.
These three main towers there are now two
new 2OO-foot ones receiving a final coat of
paint form an isosceles triangle with a base
which runs magnetic north and south. The
main antenna is lowered with electric winches
N A A
295
THE ARLINGTON HILLTOP
Showing a part of the barbed wire barrier which was charged with
twice a year for inspection and overhauling.
of the highest tower, by the way,
there is now a wind-recording instrument
tracing its records on a paper cylinder in what
used to be one of the transmitting rooms.
It
At the peak
is
precisely 790 feet
above sea
level
and
it
operates automatically, with no added labor
for the Weather Bureau.
East of the station
about 100 yards rise the two new towers, each
with an antenna strung back to the 4OO-foot
towers.
The Army built these in cooperation
with the Navy, and they are on ground owned
by the Army.
So there are now five sets of antenna, at
NAA. These, with the new towers, indicate
that, though the Navy Department is handling
its own and other Federal long-distance work
via NSS at Annapolis, NAA, at the advanced
age of not quite ten years, is setting out on new
ventures.
It has long been sending out time,
hooked up to the master clock at the Naval
Observatory but this is an old story. It has
long been sending out, every day, weather
Also Naval press
reports and ship orders.
news, so that mariners in and out of the Navy,
shore stations up and down the Atlantic Coast
and remote agencies and individuals innumer-
IN
WARTIME
electricity as a
reminder to the mean or meddlesome
able have their daily newspaper, including the
baseball scores, the football scores, almost
everything except the morning murder.
You have only to consider what time, one of
the constants in navigation, means to mariners,
as well as to jewelers, to realize a phase of the
service NAA renders when, at 11:55 A M ar d
9:55 P.M., the warning dashes flash out three
or four thousand miles in all directions, followed
"
by the longer dash that says "noon" or 10
-
P.M. "exactly, 75 degrees meridian,
Or go out with the Atlantic
news
is
better
-
Washington.
Fleet, see
how
the
welcomed, and you understand even
what
service that old spark set gives.
what the weather forecasts mean
to farmers and mariners.
Yet these are only
Or
consider
part of
disasters
A big bulk of official
about lightships out of position
NAA's work.
orders, warnings
and of derelicts
like
and
to help prevent
Titanic
Shipping
re-routings, and thousands of
icebergs,
that of the
Board orders and
other messages for the Navy or other Federal
departments are all handled via NAA.
But this isn't all; for while
is giving
over much of its former long-distance work to
NSS, the more powerful near-by Annapolis station, it is going about the business of greatly
NAA
296
Radio Broadcast
enlarging its usefulness in other directions.
On that 7,416 square feet of floor space of the
main building, which includes a well-equipped
machine-shop and much other equipment in
addition to motors from one-fourth horsepower up to 220, there are now six sending
sets: (i) The spark set; (2) a 5OO-cycle A. C.
set, for local work, such as traffic with
York, Boston, etc., and with ships out of
range of shore stations along the Atlantic Coast
and for Army work via one of the new anten-
tube
New
nas; (3) a 3O-kw arc set for Navy long-distance
traffic to Guantanamo, Key West, Cuba,
work
broadcasting general information from
other Departments, for aeronautical reports,
weather reports, etc. This set is going almost
twenty-four hours a day and uses the big anetc., for
"
;
;
'
tenna mainly; (4) a 25o-watt tube set for airplane work, using, generally, a secondary antenna swung between the two 45O-foot towers;
(5) "another 25o-watt tube set using the big an-
'
tenna, for speeches, concerts, etc; (6) a long-wave
i2OO-watt telephone tube set, for band concerts,
talks by the President and Cabinet, etc., with
which the large antenna is also used.
Three of the sets use, it will be noted, the big
antenna, but since all the four tube sets at NAA
are used experimentally, and the antenna used
with the arc set varies with the wavelength
employed, all five antennas are used in various
combinations.
Here, again, now, you see NAA
functioning, while doing a man-size routine
job, as a great experimental station.
But from the popular point of view the trans-
formations and experiments at Arlington are
interesting mainly for the following reasons:
In the first place the Army and the Navy
are for the first time consolidating their radio
forces on a large scale.
This means that the
Signal Corps, confronted with the necessity of
building a powerful station to serve, as none
other could, as the control station of its net,
was able, by pooling its interests with the
Navy, to save $50,000 or so by making use of
Arlington instead of building a new station.
There's an economy for you and other taxpayers, but the mere matter of saving money
is not the big story.
This pooling of forces
means a lot more. It means that the Army
and Navy are pulling together better than ever
before in radio; that the provisions by which
the Army handles Navy inland business, such
as traffic with recruiting stations, and the Navy
handles
Army
business to distant transports,
working out with real prom-
stations, etc., are
ise;
that the
Army and Navy have
the promise,
together, of developing an aircraft net, with
as the control station, that will, first by
NAA
supplementing the Post Office airplane chain,
later, conceivably, by cooperative work with
it, get vastly better results than ever before.
And since the radio work of the Shipping Board
is also handled
by the Navy, the Shipping
Board is also in the picture.
But the important thing is that the strengthening of NAA for other than long-distance work
alone means this: That the Government itself
anticipates the time when, with the incredibly
rapid development of all sorts of private and
public utility intermediate broadcasting stations, one Federal station can do all Federal
broadcasting to the public. And that station,
one reads the signs aright, will be NAA.
The Federal squabble in radio, in other
words, is settling, and the passing of the pending radio legislation will simplify the station
more. For months now, ever since the Radio
Conference formulated that legislation, the
inter-departmental radio board called into being by Secretary Hoover has been meeting
pretty regularly, to discover ways in which to
give all Federal Departments their due in radio
and to make the most of the situation as it
if
stands.
Even
as this
is
written, steps are being
taken to allocate to each Federal Bureau such
opportunities as it requires for broadcasting
via the Navy's Anacostia laboratory station,
NOF. And those who know the Navy's plans
is not long to retain this funcknow that
tion
NOF
NAA is to
have
it.
other words, NAA, so far as the radio
public is concerned, is on the eve of becoming
the biggest thing on the Federal horizon. Pending that time, the old giant on its hill is being
In
rejuvenated an|f in large measure re-equipped.
As a pioneer and as a great experimental station, NAA has done its bit and is continuing to
still more; yet two years ago there was serious talk of dismantling it. We have seen how,
as. a public utility, it has become almost indispensable, with its weather reports and so on.
But that isn't all. The time is coming when
even debates in Congress are to be sent out by
tube! That's cheaper and better than paper,
easier than reading the Congressional Record.
Will NAA be the station to do it?
do
Making Tubes Do Double Duty
How
Tubes
the Priess "Reflex" Circuit Uses the
for
By
FRANK
M. SQUIRE
Chief Engineer, DeForest Radio Telephone
DER
for a
moment our
utter
upon the benefits
iccruing from the invention of
he wheel and axle and the appalling, befuddled state in which
mankind would be to-day if this invention had
In just such a state would the
not been made.
radio art now rest if it were deprived of the
treasure with which it was enriched by Dr.
lependence
GNSI
Lee de Forest's invention of the audion.
Electricity is the art and science dealing with
the production, the use, and the manifestations
of infmitesimally small charged particles known
as electrons.
believe that these particles
We
are free to
move through certain materials such
which we call conductors, and are
as metals,
capable of a certain limited elastic displacement through other materials, which we call
insulators.
Although it was long known to
scientists that electrons could be made to bound
a short distance away from a hot metallic
body and would then return to the heated body,
that is to say that electrons or electricity could
exist freely in space, it remained for De Forest
to devise simple means and methods for establishing useful continuous paths for this free
space and current and other novel means and
methods for its control.
He demonstrated that he could control a
powerful stream of electrons in space by a small
electric or magnetic force and mould this
heavy stream or electric current into exact
conformance with his controlling force, the
action being not unlike a trigger or valve ac-
The layman would picture an electric
intricate maze of switches and
noisily moving parts, in a brew of magnets and
He is generally astounded to
coils of wire.
tion.
valve as an
find that
little
it is
a static device that
is
physically
more complex than the familiar incan-
descent lamp.
Dr.
De
Forest coined the
name
Audion from the Greek derivative meaning
"
1
hear the ions."
The audion
an evacuated chambulb in which is mounted a
filament similar to an incandescent lamp and
consists of
ber, usually a glass
Same
Radio and Audio Frequency Amplification
&
Telegraph
Company
from which, when heated, the electrons are emitted into the space. These electrons would bound
back upon the filament if it were not for a
second metallic body called the plate, which is
mounted in the tube and generally shaped to
The electrons may be
the filament across the space between
the filament and the plate by properly applying
a potential difference between them. The
electrons fly across the space at a terrific
velocity of the order of tens of thousands of
miles a second, making our highest velocity
bullet a mere sluggard by comparison.
The
of
the
even
and
problem
controlling
flight
stopping these electrons would appear insuperable, and yet it is accomplished by a third
element comprising a grill or mesh of fine wires
known as the grid, which is supported in the
space between the filament and plate and
through which the electron stream must pass in
going from the filament to the plate.
In this form of audion, Dr. De Forest controls
the electron stream or electric current that is
set up across the space in the tube merely by
surround the filament.
drawn
off
applying slight potential differences between
the grid and the filament and accomplishes this
remarkable action with an apparent absence of
inertia.
Complete openings and closures of
the electric valve have been effected at the rate
of hundreds of millions of times a second.
In 1912, John Stone Stone announced that
Dr. Lee de Forest had discovered a method of
amplifying voice currents, that is to say, had
discovered a method of producing a relatively
strong voice current exactly conforming with a
corresponding weak voice current by means of
an action of the audion known as its relay or
amplifying action. The audion was immediately applied to telephone lines and clear and
distinct telephony resulted from its use.
Radio engineers were stimulated by this
announcement and many circuits and arrangements were devised to utilize the De Forest
The most widely advertised of
discovery.
these is the "feed-back" or "ultra-audion"
circuit which accomplished in one audion the
Radio Broadcast
298
amplification that De Forest had previously
obtained in a multi-audion or "cascade"
The ultra-audion had the addiamplifier.
tional advantage over the cascade amplifier
in that it reinforced the radio-frequency currents prior to their rectification and thereby
increased the sensitivity or range of the receiver
when operating on weak
signals.
The
circuit
from
the great disadvantages not
present in the cascade amplifier, namely, that
it is operated at a point of great instability, and
in general use sets up the radiation of interfering pulses which interact with the transmitted
waves and cause the familiar squeals and
whistles that are so annoying to the broadcastThese interfering pulses
ing radio audience.
also interact with the transmitted waves to
"
cause a most disagreeable distortion or mushing" of the received speech or music to the
entire locality within the range of the radiating
suffers
receiver.
Due
to the low cost of production and the
inexperience of the broadcasting public,
enormous quantities of the whistling or interference producing types of receivers were
placed on the market and absorbed by the
initial
public last winter.
The worst
single-circuit set of this
offender
is
the
type designed for use on
an open antenna.
The future of broadcasting demands the
retirement of all forms of radiating or interfering sets. A constructive programme might be
worked out along the lines of the modification
in the objectionable types of sets now in the
hands of the public by the original manufacturer and a re-design of the present product
of the manufacturers whose equipment radiates
or interferes in the process of normal adjustment. The addition of a simple device to the
existing
nominal
receivers
makes
this
possible
at
Forest
pioneered the
broadcasting of music and entertainment as
early as 1913 and appreciating that an inevitable Radio
employed by them
Company
Tower
of Babel
from a dense operation
of
would
result
ultra-audion and
other varieties of "whistling" receivers, produced for this use only such types of receivers
as were strictly non-radiating.
In the meantime their research organization was busily
occupied in attempting to devise a receiver
solution that would combine a great sensitivity
and still be free from the production of radiating interference of either the "mush" or
"whistle" types. After many disheartening
is
in
their design of the
Priess "reflex" receiver.
This receiver
is
a three-audion design that
a
It
will
very great sensitivity.
provide good telephone reception without any
form of antenna and merely the tuning coils in
the receiver at distances of approximately fifty
miles.
It will give similar reception from a
two-foot coil antenna with which the set is
equipped over ranges in excess of 1000 miles.
If an open antenna is used with the set, it need
merely be a short wire run entirely inside the
house from the receiving set to the moulding
around the room and thereby completely dispense with lightning switches and the usual
elaborate outside rig. An outside antenna may
be used if desired without emitting interference.
Added to these advantages of extreme sensitivity, the elimination of the outside antenna, the
property of directional reception, and freedom
from the production of interference, are a
possesses
superior quality of distortionless reproduction
that faithfully records the modulation of the
transmitter, a small number of operating adjustments and a pronounced stability.
I
am certain that the readers of RADIO
BROADCAST will welcome a brief outline of the
history of the conception and effort that
culminated
in
the
invention
of
the
Priess
amplifier system, since this romance has never
been made public up to the present time.
In
with the prospect of war with
increasingly apparent,
William H. Priess, then a U. S. Radio Inspector
attached to the Second District Office, entered
the Navy, and thereafter joined the Radio
Engineering Design and Research organization
April,
1917,
Germany
at the
cost.
The De
failures their efforts were realized in their
acquisition of rights under the Priess amplifier
inventions and the particular embodiment
becoming
Washington Navy Yard,
at first in the
capacity of Radio Electrician and then as
Radio Expert Aide. He remained there until
he entered the U. S. Army in January, 1918, and
sailed overseas.
From the skeleton force of
1917,
April,
comprising Lieut. W. A. Eaton,
U. S. N., Radio Expert Aide L. L. Jones, and
Priess, the Washington Navy Yard radio organization was built up by hard work and the
acquisition of additional talent to the most
productive radio research, design, and developin this country.
They were
with
the
development and
charged exclusively
design of all radio receiving and amplifying
apparatus to be used by the Navy and with the
ment organization
Making Tubes Do Double Duty
299
prosecution of vacuum-tube development and
In April, 1917, the Navy Departproduction.
ment did not possess a receiver or amplifier of
own design, excluding minor modifications of
standard apparatus of other manufacturers.
The existing receivers in use by the Navy were
its
very poor in selectivity. None of the oscillating forms of receivers would actually oscillate
below 800 meters. Amplifiers were not in general use, owing to a lack of the necessary audions and the general unreliability at sea of the
types then available. There was a severe
shortage of
vacuum
No
tubes.
approved airequipment was
available.
Ten months later, due to the untiring efforts of Eaton, Jones, and Priess and
the support of others in the Navy Department
(notably Commanders Hooper and Le Claire),
the entire aspect of the situation had been
altered.
The Navy was in possession of its own
designs of selective receivers for ship, air, and
shore application that ranged from 35 meters
to 25,000 meters and regenerated all over this
craft transmitting or receiving
range, audions in such quantities that store
stocks could be maintained, amplifiers, and
many special devices which are confidential
naval data.
In addition, the ice had been
broken on tube transmitter design, and numerous improvements devised for arc transmitter
and certain
signaling,
developed that
permitted the simultaneous transmission and
devising methods for locating and exterminating the undersea peril of the German submarine.
Jones evolved a system of submarine detection
based upon magnetizing the steel hull of a
vessel with an audio-frequency alternating
magnetic field, and arranging coils on either side
of the field near one of the poles in such manner
that when cross-connected with a receiver they
balanced out the electromotive forces induced
in them.
If media of greater permeability
than water were introduced on one side of the
ship for example, the iron hull of a submarine
the flux from the ship through the space on
that side would be increased and the balance
disturbed.
Either an orientation of the coils
or the ship would give a direction line and a
base run establish the location of the hidden
menace. The solution was a very ingenious
one but not considered by Jones of sufficient
range to have warranted
worked on
M. SQUIRE
of this article, completed models of the
"reflex" receiver last summer and has had excellent
results
from them
in rigorous tests
circuits
reception from a single station.
During the war, all technical minds in Navy
service and employ turned for recreation to
Priess
FRANK
The author
its
installation.
his pet
theory that the
submarine would, when running under water,
emit a complex but regular high-frequency radiation, modulated by some complex but regular
low-frequency envelop due to the high-frequency
oscillations set up by the sparking of the
brushes on the commutator of the electric
driving motor and the modulation affected by
the regularity of this sparking and the influence of other pulses due to parasitic effects
of pole tips, short resonant circuits, and so on.
This radiation should be capable of directional
reception.
Its
regularity
and
characteristics
should serve to identify the type and speed of
the submarine.
He reasoned that the predominating radio frequency would be at the
natural period of the submarine hull, and that
the predominating audio-frequency modulation
would depend on the sparking rate, that is, the
He
speed and number of commutator bars.
concluded that the receiving device would have
to be several orders of magnitude more sensitive than existing receivers since the pulse
would necessarily be weak and that the investigation should include all frequencies since
no German submarines were available to
Radio Broadcast
300
measure the predominating radiated or moduBenefiting greatly from
lating frequencies.
the tube tuition and experience of Jones, and
the open grid circuit audio-frequency amplifier
designs of De Forest, he plunged into this
problem early in May and by the middle of
January, the following year, had evolved many
of new fundamental principles,
methods, processes, and apparatus for stable
highly efficient amplification of any frequency
from the high radio to the low audio frequencies,
non-distorted audio-frequency amplification,
the control of the breadth of band of an ampli-
discoveries
fier,
certain simple circuits for heating filaments
of a receiver "or amplifier audion
from a
t
many
ling
line,
designs and principles relating to coupmeans between audions to effectuate
,
and many important amplifier
amplification,
circuits.
Results were netted mainly from methods of
attack based upon conceptions of physical
actions and reactions in the coupled tubes as
not much different from the familiar reasonantcoupled circuit solutions evolved in quenched
',
spark-transmitter practice with accp.unt taken
for the amplifying constant of the ffibe, its
grid and plate circuit characteristics and the
capacity couplings between the tube elements.
Priess designed and released for production before leaving the Navy several amplifiers, the
most widely known being the Type S. E. 1000.
The United States Government has prepared
and filed a patent application on the Priess
amplifier inventions, receiving a license for
government use and ceding all title and commercial rights to the inventor.
The "reflex" set of the De Forest Company
is
known
designed
and
it,
as
their
as a
receiver.
Type Dy.
The author
combined three-tube amplifier
The
receiver includes
a two-
and tuning condenser system.
It has a wavelength range of 250-500 meters
with an adequate overlap. The original model
of the Type Dy included a
primary and secondary coil system to provide reception from an
open antenna via the usual two-tuned circuits.
In the later models the coupler has been replaced by a vernier condenser although posts
are retained for antenna and ground connection
to permit the user the same flexible antenna systems and at the same time reduce the number of
In this form, if an open
adjustments in the set.
antenna is used, it is always used in combinafoot coil antenna
with the coil antenna. The received
powers of both open and coil antenna are then
tion
additive and both antennas are simultaneously
.tuned by the same adjustment knob. The
coil antenna is a pancake coil of a size usually
found in transmitter loading inductances.
It
operates to receive via the electric and magnetic components of the wave jointly as shown in
the coil or directive antenna patents of Lee
de Forest and John Stone Stone owned by the
De Forest Company and not, as popularly
believed, as a receiver solely of the magnetic
component of the wave. The latter is a
phenomenon
of induction
and not of radia-
tion.
The received power stored in the tuning
condenser is impressed upon the grid circuit of
the first tube and is then amplified through
each of the three tubes at radio frequency,
building up the received signal from an infinitesimal value to a very great amplitude.
The^signal is then rectified by a galena crystal
detector and "reflexed" back and its potential
raised through an audio-frequency transformer
to the grid circuit of the second tube.
It is
then further amplified at audio frequency in
the third tube and the complete output drawn
off the plate circuit of this tube.
A control
is placed in the grid circuit of the first tube
to enable a continuous variation of the grid
circuit damping over a range resulting from the
grid current losses that follow the change of
grid potential from a value of zero to a positive
value equal to the potential drop across the
filament.
This is not a grid "bias" for the
purpose of securing rectification or operation
on the non-symmetrical portion of the tube
characteristic nor an application of grid potential for the purpose of securing operation on
the symmetric portion of the tube characteristic as clearly evident from the range of these
values and the fact that neither of these effects
if present are in any manner useful in the Type
Dy circuit. All the remaining grid circuits of
the amplifier are tied in permanently at zero
potential and are therefore in a condition
essential for them to be highly efficient amplifiers.
in
The type of radio-frequency amplification
the Type Dy is of such form that it provides
an enormous
sensitivity
accompanied by a
correspondingly great stability.
over a very wide band. The
It is
effective
transformers
an insulation between primary and
secondary sufficiently great to safely withstand
potential differences of the order of 500 volts.
Since all detectors have a threshold value,
have
1
Making Tubes Do Double Duty
301
TRYING OUT THE REFLEX RECEIVER
Left to Right: Arthur H. Lynch, Richard Wagner (whose remarkable no-aerial receiver was
described under "How Far Have You "Heard?" in the December issue), and Frank M. Squire
that
is
to say they require a certain appreciable
value of radio-frequency amplitude
minimum
before they are operative, the problem of distant or sensitive reception necessarily requires
a system of radio-frequency amplification prior
to the detector to attain at least this threshold
value.
It is an error to evaluate a detector
followed by a powerful audio-frequency amplifier
as the equivalent of a correspondingly powerful
radio-frequency amplifier feeding a detector,
for the reception of weak signals.
The radio
satisfactory; the audio
the threshold value of the
detector is not attained, the following audio
steps have nothing to amplify; the radio frequency steps start at an infmitesimally lower
limit and are effective up to the point of saturation of the detector.
In radio-frequency
amplification there is no tube or transformer
noise and if the correct principles and method
are employed in the design there is no distor-
frequency solution
solution
tion.
is
not, for
is
if
Very high audio-frequency amplification
accompanied by tube noise and, in certain designs, by transformer noise and generally plays
is
an independent tune of
crackles.
It is
also very
susceptible to distortion.
The receiver employs a crystal rather than a
tube as a detector. This use of a crystal
sensitized by a radio-frequency amplifier be-
tween
it
and the antenna has never been
previously applied to commercial sets due to
the presence of many difficult problems inRadio envolving instability and reaction.
gineers have for a long time appreciated the
inherent value of the solid rectifier in this
general use, but it remained for Priess to solve
the problems in a balanced adjustment, free
design, and attain the inherent benefits accruing
from its use. Some of these are a total absence
of parasitic noise at the rectifier which ordinarily occurs in a detector tube and is amplified
at audio frequency to a disagreeable amplitude,
the relatively greater freedom from distortion
of a crystal as compared with a detector tube,
the elimination of a number of detector-tube
adjustments and the necessity of changing
them very materially as the tube ages, and the
saving of a tube and the filament and plate
:
Radio Broadcast
3O2
powers required to operate it. In this use of
a crystal, all points on the crystal give reception and the adjustment of the contact point
merely gives a variation in the received signal.
Furthermore, the adjustment will remain fixed
for
months
since
the factors which
crystal circuit.
not effected by static or
are present in the usual
it is
The
crystal
is
both electrically
and mechanically cushioned against both types
of shock.
In the Priess "reflex" circuit, used in the
Type Dj, the vacuum tubes are made to
perform simultaneously a double duty,
first
as
amplifiers of radio-frequency currents and then
inas audio-frequency amplifiers without
and with each amplification
separately efficient. Added to this phenomena
there is a certain amount of radio-frequency
"reflex" which is accomplished by adding to
the combined amplification some of the doublefrequency radio frequency generated in the
detector circuit and led back via the mutual
capacity of the transformer windings and the
stability or squeals
capacity of the wiring
"Reflex"
is
and
circuits in the set.
not feed-back or regeneration.
In
changes in plate-circuit potential
caused by corresponding grid-circuit potential
variations are reimpressed in identical wave
form, phase, and frequency upon the grid cirfeed-back,
and they
cuit
result in additional
changes
in
In the
plate potential, or an amplification.
which
an
circuit
of
"reflex"
output
phenomena
may be a grid circuit or a plate circuit or
a circuit coupled to either or both of
passed through some device which
all three of the characteristics of the phase, wave form or frequency
of the output wave, the resultant
which is
and
of
a
form
may even be
usually
complex
discontinuous periodically is then impressed
upon a grid or a plate circuit of the tube device
which is primarily causing the "unreflexed"
them
is
changes any one, two, or
Reflex may be at higher frequency
output.
than the output frequency and usually a
harmonic, or at a lower frequency, or both
step up and step down may be simultaneously
present.
Several reflexes are possible simultaneously
In feed-back, factors are present to
a tube.
In reflex no such
hold the system in phase.
factor is useful in most of the simple forms.
The writer completed models of the Type
Dy in August and has since had them under
In one of the tests the set was
rigorous tests.
in
antenna inside the metal
a
body
Hupmobile sedan with the intention
of determining both the action of the set in
dead localities and its daylight range on the
Newark, N. J., station. Tests were made every
five miles without removing the set from the
car.
At sixty-five miles from Newark, no
appreciable reduction was found in the received signal and this test was abandoned.
Good reception was had at all the notoriously
installed with its coil
of
"dead" spots on Long
of the
machine did not
Island.
The jouncing
affect the crystal de-
tector adjustment during these tests.
Tests
were made with the set installed inside of steel
frame buildings in the heart of New York City.
Both local and distant reception was very good
under these conditions. At his home in Bay
Ridge, N. Y., the writer has received practically
all of the stations east of the Rockies and north
to Buffalo
and south to Havana using the
coil
antenna provided with the set. Good success
has also been had by backing up the output of
the set with power amplifiers for the entertainment of a group of listeners.
Owing to arrangement with the inventor
certain of the methods, principles, processes
and apparatus involved in his invention are
being maintained as secret, and it is regretted at
this time that these details cannot be made
public.
The "Ham" What
By ROBERT
AM just beginning to find out why
remain
in
China.
I
left
I did not
there 'sooner than
I had
planned as 1 felt I was getting out of
touch with radio development at home.
Letters from my friends told obscurely of
the remarkable inventions that had taken place
I
months of my absence; of how
broadcasting had revolutionized both transmission and reception and that would have to
begin all over again and learn the new game of
But the temptations to stay were many.
1922.
had learned to like the Chinese people with
whom was doing business and they in turn
almost refused to let me go. They insisted
that
should stay with them for another year
at least, working out their radio problems
in the short nine
I
I
I
I
which, though difficult, were intensely fascinatfelt
could not afford to get behind the
ing.
times.
And now am just awakening to the
fact that it was not being out of touch with the
new development that was worrying me but
I
1
1
that
was hankering to get back to my old
amateur set and into the game again as a
"
Ham," which, after all, gives us more pleasure
I
than the professional phase of radio.
And what
did
find on my return?
Listenon 200 meters brought back the old thrill
that one gets when he is able to copy a little
code after a long struggle as an amateur to
learn it and to send it out with a home-made
I
ing in
transmitting set made up of miscellaneous junk
There were a
parts at a minumum of expense.
few of the oldtime buzz-saw rotaries asking
each other "QRK" and "QRU" with the usual
noticed an increase
"MSG," etc., tacked on.
in the number of
and ICW sets though the
traffic was pretty light, it being the off season
when the static was bad. I tuned to 360 meters
and heard a babel of phonographs sending out
the inevitable jazz just as
and many others
I
CW
I
had done some two years previously.
began to look for the new developments,
and beyond the Armstrong super-regenerative
circuit, the value of which seems to be somewhat questionable in its present state of develI
opment, I am still looking for them. In other
words the stunts which we, as amateurs, had
tried out and discarded as worthless have now
been commercialized to be inflicted upon the
F.
Am
GOWEN
I
had heard that some
unsuspecting public.
wonderful thing had been brought out by which
you might use the electric wiring in your home
as an antenna and thus do away with expensive
outside aerials forever.
found it to be nothing
but a condenser such as we used in attempts to
I
employ
electric light wiring
and telephone
lines
as aerials in the old days, the only difference
being that the condenser was now moulded into
a plug form that would screw into the ordinary
electric light socket.
The results obtained
with it were identical with those we used to
obtain,
i.e.,
practically
negative.
So now
I
am
not quite so worried about being behind the
times except in one respect and that is that I
find that practically all my old amateur pals
have also been commercialized and are now
operating broadcasting stations or acting as
chief engineers for the thousands of radio manufacturing companies that have sprung up during
the past year.
Broadcasting progressed as the public got
of "canned" music.
The Government
was forced to allot a 4oo-meter wave to superbroadcasting stations which were not allowed
to transmit music of the "canned" variety and
were therefore compelled to send out something
worth while. This was excellent and a great
And then what happened?
step in advance.
The public who were beginning to enjoy broadcasting were beginning to hear strange things
with the many cheap, single-circuit tuners that
"
the thousands of illegitimate, so-called radiomanufacturers" forced upon them. These
strange numbers which were not on the programme consisted of dots and dashes which
interfered with the listeners' enjoyment of the
music, and Mr. Public, having read in the papers
that the country was infested with amateurs
tired
immediately said to himself, "Why, that is an
amateur next door bothering us and he has no
right to play with his apparatus when we want
to hear this music that is so worth while!"
And so to-day, the "Radio Fan" as he is
popularly known, is attempting to bring legislation to squash the amateur and put him out of
business on the ground that he is a nuisance and
is merely playing with a toy that bothers other
But Mr. Public does not stop to realpeople.
34
Radio Broadcast
THE HUB OF THE RADIO UNIVERSE
Mr. R. H. G. Matthews, known to hams as "Matty, "
is
ize that
so-called because, located in Chicago,
it is
is
here
shown operating the "hub," which
amateur messages in all directions
a clearing house for
if this is true
perhaps he too is playing
with a toy for his own amusement.
He does
not understand or appreciate what "waveHe does not even know what
length" means.
kind of a circuit he is using for reception and
that if he used a different type of circuit, perhaps a little more expensive or perhaps even
cheaper (if bought with more intelligence), he
would not hear the dots and dashes when he
wanted to hear music. He does not know
that if he had the proper type of receiver and
knew how to tune it he could hear either dots
and dashes or music at will, one without interAnd the
fering in the least with the other.
problem is, how are we going to educate him to
these facts so that he may play at the same time
that the amateur is playing?
But does the amateur play, and what is a
"ham" anyway? Perhaps not ten per cent,
of the readers of this article know the proper
definition of the word "ham."
And yet it is
very simple. A "ham" is not a small boy
using a spark-coil, jamming up the ether with
noises sounding like a boiler factory in action,
but a young man of the average age of twenty
who has enthusiastically studied radio
both theoretically and practically and whose
idea is to better the art in any way he can by
He has solved many
unselfish application.
problems that have confronted him, not for
financial gain,, but for the love of the thing.
years
The very apparatus that you are
using to-day, as
that
is
sending its music
equipment
to you, is the result of his effort and conscientious endeavor.
The man who announces at a
well as the
broadcasting station is a "ham." The man
operates the broadcasting transmitter is
a "ham," and the man who designs your reWhy? Because no
ceiving set is a "ham."
one but a "ham" can do these things. When
was chief engineer for the De Forest Company,
designing among other things radio telephone
transmitters, purchasers would ask me to get
them men to operate the equipment that they
who
1
"Ham" What Am
The
Do you suppose I could get a combought.
mercial operator to operate a radio telephone
set?
No. I found they knew absolutely
nothing about it and in every case I had to get
a "ham", simply because the former was a man
who knew only how to press the key and read
code while the latter was a technician who had
trained himself in the fundamentals of radio
and knew how to analyze the circuit and keep
it functioning properly in addition to his knowledge of key pressing. Likewise, every man
had in my laboratory was an amateur, not because
was one but purely because they were
the only men obtainable who could tackle the
problems placed before them. The question
naturally arises, "Why does the amateur have
such enthusiasm and why does he not lose
"
The answer is 'sportsinterest after a while?
manship/' This sportsmanship is the finest
I
1
'
type we know of, as it is dependent for its existence on personal unselfishness in not interfering
with the other fellow, a sportsmanship that
breeds good fellowship. Then there is the
mystery and
thrill
of
it
and the tremendous
incentive to
And some
305
beat the other fellow's record
of these records are hard to beat.
Fellows on the Pacific coast and some as
fai
"work" an amateur
in
east
as
Minnesota
Hawaii nightly. Figure the distance for yourself and remember that these stations are restricted to an output of
kw. of power and usuless
than
this
amount. And this
ally employ
i
with home-made apparatus!
Everyone knows of Frank Conrad, assistant
Westinghouse Electric and
Manufacturing Company, and Paul Godlev
who went to Scotland to listen for the transatlantic tests of the amateurs.
These men are
"hams" through and through, always were and
always will be, and there are hundreds of prochief engineer of the
them though they are not sc
known. Did you ever hear of Mr. H. P,
Maxim, President of the American Radio Relay League and his fine station that does
remarkable things at Hartford, Conn.? Then
there are Irving Vermilya at Marion, Mass.
"Johnny" Clayton at Little Rock, Ark., J. A,
Gjelhaug at Baudette, Minn., A. L. Groves al
fessionals just like
well
;
QQK, A PRE-WAR STATION
and operated by John
A. Gjelhaug, Baudette, Minn.
Built
(ABOVE) MR. GJELHAUG'S
Located
ture
in
was
NEW
STATION
Baudette, Minn. This pictaken November 27, 1922
Radio Broadcast
306
Brooke, Va., C. R. Runyon at Yonkers, New
York, Mr. and Mrs. Charles Candler at St.
Mary's, Ohio, and a host of others too numerous
to mention, all known from coast to coast for
their untiring enthusiasm in American amateur
radio.
There
the ever popular
"
"-
Matty
Matthews of Chicago, one of the best
"
"
known hams in the game. And yet he never
is
awoke to the fact that there
them located all over the counThe thing that awakened them was the
try.
Federal Radio Law of August 13,1912. Among
other things which this law provided was a call
book and this book contained the names and
teurs in the East
were a
lot of
R. H. G.
addresses as well as the
He is not of the
did anything very startling.
But he runs a station, 9ZN,
fireworks type.
that has been called "The Hub of the Amateur
amateurs who had passed the necessary tests
to secure transmitting licenses.
The book disclosed the astounding fact that there were
several hundred of them scattered over the
various States of the Union.
It demonstrated
Universe" because it can be absolutely depended upon to relay messages north, east,
south and west, a thousand miles or more any
It has been built and renight without fail.
built by Matthews and his assistant operators
to a remarkable state of efficiency which every
Then too
true sport is bound to admire.
"Matty"
is
the manager of the Central Divi-
A.R.R.L.
A.R.R.L., the American Radio Relay League,
is an organization of thousands of these amateurs, conducted by and for amateurs. It came
sion of the
into existence in the old days after the
THE AERIAL
With
IS
ama-
call letters of all
the
immediately that it was a good thing to observe
the law and take out a transmitting license because it established one's standing and gave one
a dignified position among the better amateurs
of the country.
radio club.
It
With it came the birth of the
came from the natural tendency
to gather together
and exchange experiences,
information and knowledge.
In this way the
radio club became the meeting ground of the
amateurs and presently there came into being
a wonderful spirit of fraternity. One felt a
queer little thrill at these early radio club meet-
OUT OF THE WAY UNDER THE TOP
Mr. Gjelhaug has heard long-wave arc stations hundreds of miles away with a single tube. While
the car was making twenty-five miles an hour, he has copied signals from a spark-coil transmitter using 12 watts input, up
this portable set,
to five miles
The
"
Ham " What Am
307
ings when he came face to
face with the fellow he knew
whom
well in the air but
had never
who
he
To one
seen.
has never sat in his
little
back room
late at night
and conversed with another
seated in bis
fellow
little
back room away over in
some remote town, and then
come
finally
hand
of
to
this
never come
grasp the
fellow, can
this peculiar
thrill.
The
radio club
natural
relay.
was the
birthplace
of
probably
It
the
de-
veloped in the minds of several of the clubs at
about
the same time, but it was in
the Radio Club of Hartford,
Conn., that the relay idea
which finally became the
American Radio
League
form.
Relay
took practical
was born of the
first
It
one amateur in
found he could
communicate with another
amateur in Windsor Locks,
25 miles away. If Hartford
could reach Windsor Locks
which was half way to
fact that
Hartford
Springfield,
why
could not
MR. GOWEN S STATION IN OSSINING, N.
The tube transmitter, mounted on the upright panel at
Windsor Locks reach Springfield?
And
if
this could be
is
used for broadcasting and has been heard
done why would it not be
possible to branch out and to eventually link
up with amateurs in distant parts of the country? The idea was an incentive for the amateur to study and work harder and to improve
his
apparatus to cover
great
distances,
to
simplify it and to make it more practical.
Just look at the result! To-day the whole
United States is divided into operating diseach supervised by a competent and
tricts,
enthusiastic amateur
who
is
responsible for the
and through his district. He appoints amateurs to take care of traffic along
traffic
in
now
there are trunk lines
from one end of the United States to the other,
certain lines so that
North, East, South, and West by means of
which messages may be sent to any point in the
United States. The organization is so perfect
that substitute stations and even alternate
all
Y.
the right,
over the country
handle a message should
an amateur on a regular trunk line be out of
commission for any reason. Monthly reports
lines are established to
made by the Division Manager
Manager at the headquarters in
of the traffic are
to the Traffic
Hartford, Conn., and these are published in the
organ of the League, a truly remarkable
official
"QST." The nominal
dues of the association go to pay the expenses of
publishing this magazine which is no small
matter and requires to-day a rather large office
magazine known as
force.
What have the amateurs accomplished by
such organization? To begin with they have
maintained their very existence by it for attempts have been made from time to time to
legislate against them.
By appointment of
the present vice-president, Charles H. Stewart,
Radio Broadcast
308
chairman of the Legislation Committee of
the Association, it has been strongly represented at all hearings of radio bills in Washington with the result that bills detrimental to the
interest of amateur radio have been tabled.
Such representation has been of vital importance and the amateurs are now called in for
consultation on important matters of radio
policy so that Mr. Stewart and others were
as
at the Radio Telephone Conference
by Secretary Hoover last Spring.
The record of war needs no telling. These
young amateurs to the number of nearly five
thousand gave to Uncle Sam in his Army and
present
called
the best radio operators the world has
It is no reflection upon the Navy or
Army operator to say that the amateur beat
him at his own job. The amateur had developed his extreme expertness because of his love
Navy
seen.
and he represented furthermore
young men of the country. No
matter where one went in the Army or in the
Navy during the war one encountered the
amateur on every hand, from the high officer
The chief operators in all
to the enlisted man.
of the important stations were ex-amateurs.
When President Wilson journeyed to France
for his hobby,
the pick of the
and back, the chief radio operators on the
George Washington were ex-amateurs.
And now all -of these young men are amateurs
again, and in these days of peace, they have rebuilt their organization.
Their recent accomplishments are a good indication of what they
and what we may expect of them in the
Over a year ago they decided to demonstrate what their organization could do in
the way of a rapid interchange of messages from
the Atlantic to the Pacific and back, and from
the Canadian border to the Gulf of Mexico and
back. A series of messages was started from
Portland, Maine, Boston, Mass., Hartford,
Conn., New York, and Chicago, and destined
for points on the Pacific Coast and on the Gulf
of Mexico.
Each of these messages had to be
are
future.
relayed through several stations, the message
answer secured, and this answer
transmitted back to the starting point.
delivered, the
A
Portland, Maine, organization sent a message
to a Portland, Oregon, station, and received its
answer back within an hour. Similar messages
went from the various points mentioned. One
message originated in Hartford, Conn., and
to one of the amateurs in Los
From the time that this mesAngeles, Calif.
was addressed
SOME BROADCAST ENTHUSIASTS PROCURE ELABORATE APPARATUS
For the purpose of getting the distant stations.
In a receiver of this type there are entirely too many
"
"
adjustments for the ham to bother with, especially where rapid DX (long distance relay) work is carried on
The
"Ham" What Am
309
THE STATION OF HAROLD ROBINSON AT KEYPORT,
2QR
When
N.
J.
was of better design than that employed on most commercial
built, the transmitting apparatus of
vessels.
However, spark transmitters are rapidly going into the d'scard in favor of the continuous wave system.
The tube transmitter which supplanted
the one
shown
sage started its first dot at the key in Hartford
to the time the answer was received back from
Los Angeles and all written out on a telegraph
blank was just 5*'* and one half minutes. This
message was relayed at Chicago and Roswell,
New Mexico, and the esprit de corps was such
that the entire country full of amateurs re-
mained quiet during the interval of the tests so
that every assistance might be given to a quick
transit.
Within the past year it was decided the techadvance in Amateur Radio and the advance in organization had been such that the
nical
This
greatest of all feats might be attempted.
to span the Atlantic Ocean by amateur
was
and establish communication between
the amateurs of America and those of Great
Britain.
These young men selected one of
their number, Mr. Paul Godley, to go to Europe
and look after the reception and encourage the
English amateurs to take an interest in the
matter. All the expenses were borne by the
amateur organization. The result of 'the
wireless
transatlantic tests are a classic in radio history,
more than thirty American amateur stations
for
were recorded
ember 22nd
atoms when
in
last,
message to 6
i
the British Isles. On Novall records were smashed to
at Hartford, Conn., sent a
AW
ZAC
in
Hawaii via 9
AWM
at
at the left in this picture
was heard
in
Aberdeen, Scotland
Sleepy Eye, Minn., and the answer returned in
just/owr minutes and eighteen seconds. 9
was the only intermediate station
There is no
where
these
men
.will
telling
young
carry
AWM
!
American amateur radio and it is very safe to
assume that it will not be long before they ^will
be exchanging "messages regularly with their
brothers across the seas.
In addition to their own interests in intercourse among themselves they have been of
material -benefit to radio in general because
the mother of invention" and,
to work with, they have been
forced to find a cheaper and better way out of
"Necessity
having but
is
little
their difficulties.
In 1920, as an organization,
the amateurs of this country collected data for
the Bureau of Standards which was not obtainable from any other source in the world.
Night after night the "hams" sat up and made
fading tests on signals sent put from several
selected stations in the hope that the data collected would give some insight into the cause
of fading as a basis on which to combat it.
An analysis of the results obtained, however,
showed little of value at the time, but it is
believed that later when we know more about
the peculiarities of the ether this data will be
of inestimable value in overcoming this or
similar problems.
Radio Broadcast
3io
The amateurs have checked and rechecked
test
after test at the request of the broadcast operators and it is safe to say that without the amateurs, broadcasting would never have developed
to its present state of efficiency in so short a time.
In fact, broadcasting could not have existed
without the amateur for he is responsible for the
education of the public in the use of receiving
apparatus, by inviting his friends to hear the
music at his own set. Broadcasting is impossible without an audience and without the amateurs there would have been no audience.
then, that men who know as
radio as outlined above; men who
Is it possible,
much about
have designed, constructed and operated the
broadcasting stations; men who are conscientiously fair to their brothers in handling traffic
and
in interference questions;
men whose activi-
have been used many times by an ignorant
press as an excuse to cover up some shortcoming of the radio service which has been due
to other causes; men who know fully and appreciate the limitations of radio communication
and who have therefore unselfishly and without
restraint of law agreed to stop transmitting
between the hours of 7 and 10.30 p. M. to make
ties
certain the
is it
enjoyment of broadcast
possible that these
men
listeners
maliciously inter-
with the work of broadcasting stations on
a wavelength removed from that allotted to
fere
them by law? Why should they deliberately
wish to go out of their sphere of communication
and trespass upon the rights of others, especially since the advent of the Armstrong. Superregenerative Circuit tends to make for transmission on wavelengths less than 200 meters.
The amateurs have no axe to grind even
though in all fairness it must be said that the
broadcasting stations, because of their high
power output and improper tuning in some inAll they want is to
stances, do bother them.
be let alone that they may go forward and
develop in years to come with the same remarkable advance as formerly.
They agree, as we
all
agree, that there is a place for broadcasting
a most important place with its Philhar-
monic and Symphony Concerts, its Grand
Opera and its sporting events as amusement,
together with its stock market and weather
reports of inestimable value to the public in
It is fast becoming a public utility
that cannot be dispensed with.
But American
amateur radio must also exist, for of it broad-
general.
casting was born and without it broadcasting
cannot continue to develop to the unforseen
heights to which we are sure it will climb.
There are places for both amateur radio and
broadcasting, and the solution of the
them is a mutual understanding
of each other's rights.
radio
clash between
\
Proper Radio Legislation
is
Urgently
Needed
By
Chairman
of the
S.
W. STRATTON
Committee Appointed by Secretary Hoover to Study Radio Regulation as Discussed
Chairman of the Inter-Department Radio Board
fullest
utilization
plies, of course,
of
radio im-
better understanding
and principles concerned
and the improvement of apparatus
for sending and receiving.
But such
of the laws
THE
existing problems as that of static interference,
and the need of increasing the selective power
of receiving sets in general use, only serve to
emphasize rather than to diminish the need
for such relief legislation as that formulated by
the Radio Conference.
In the present situation there is no substitute for that legislation.
clearly necessary to readjust the allocation of the wavelengths that are practicable for
It is
broadcasting.
Within the limitations estab-
at the
Washington Conference, and
by the law of 1912, the inter-departmental
board called together by Secretary Hoover has
sought, in cooperation with the Bureau of
lished
Navigation, to facilitate the largest possible
use of available wavebands. What is clearly
needed, however, is the removal of many of the
present legal restrictions so far as that is practicable.
The bills now before Congress do not
fix the details but give the Secretary of Commerce authority by which to make and to enforce such adjustments as conditions warrant
and progress
requires. Such authority, based
on general terms, is particularly needed in a
situation which changes rapidly and has so
large a promise of usefulness as radio affords.
ELECTRON
TRAFFIC COP
\
I
REDUCES INTERFERENCE
Preventing Confusion Along the Ether Highways. What
to Do with the Road Hogs and How Not to Be One
By
R. H.
RANGER
Engineer, Radio Corporation of America
Illustrated
The
traffic
down Main
Street of
by
TOM MONROE
a Saturday afternoon
is
nothing compared
to the electron
congestion
down
the aerials of the million receiving sets all over the continent.
Federal, commercial, and amateur
interests are doing effective work in establishing traffic rules and schedules; and each set owner can
assist in
making this ether highway of the greatest possible service to the country; first, by seeing to it
that he is not interfering with other listeners by radiating energy from a too "tightly" coupled "feedback," and second, by making his own equipment as free from interference as possible.
of
all
kinds
electric
motors, X-ray machines, and
power
worst of all, interference between radio
transmitters themselves is now the bugbear of the listener-in.
It is no longer a
of
not
question
hearing enough, but rather of
hearing too much!
First, the non-radio sources of interference.
If the disturbance comes in as a soft humming
sound, the trouble is most apt to be in the
insulation from the ground or building to the
This interset, the batteries, or the aerial wire.
ference is not of a wave variety at all, but comes
in by direct conduction of the electricity from
a lighting or power source.
If it is on the aerial, disconnecting the receiving set from the aerial with the set still on
will produce silence.
With the trouble lolines,
INTERFERENCE
calized in the antenna, the antenna should be
looked over carefully to see where it comes
nearest to any such power source. This is apt
to be inside the building. To determine if it
reconnect the aerial to the set and disis,
connect the outside portion of the aerial where
it enters the building.
If the noise still continues, the leak is evidently between the outside connection and the set.
All radio wires should be kept as far as possible away from lighting wires.
If it is necessary
to cross lighting wires, as great an air gap should
be maintained as possible between the two, and
insulators should support the radio wires as well
"
as the lighting wires.
Loom " or porcelain tube
insulation should cover the radio wires where
"
they cross power wires. This loom" is flexible
insulating tubing.
Radio Broadcast
312
The storage battery and dry batteries connected to a radio set are distinctly in the radio
circuits so they should be well insulated from
any possible extraneous currents. If the battery is kept dry on the bottom, no difficulty will
be experienced. This will be the case if the
battery is kept off the floor with two small
pieces of hardwood, or preferably with four
These insulators may be screwed
insulators.
to a piece of board
slightly larger than
the bottom of the battery, which acts as a
stand.
Motors. These are
the next most common
source of outside interference. Naturally,
one of the simplest
answers to any of
disturbances
these
is
to keep as far away
from them as possible.
However, such
inter-
ference can be greatly
reduced and even com-
eliminated,
with care. The first
pletely
thing to do
is
to deter-
mine what motor
fault.
This
is
will
at
be
done of course by ob-
serving
when the
trouble
caused, and
is
determining what motor
goes on
time.
at
that
The same
effect
which makes a motor
interference
is most apt to be
detrimental to the motor
station,
feet
if
possible.
may make
A
fifty
Noisy Grounds. The ground wire may be
picking up a great deal of interference. The
method of determining this is of course the
same trial of connecting and disconnecting the
ground wire from the set. If the ground wire
does bring in noise, try a different type of
If a water pipe has been used, try
ground.
the radiator which
should be good in the
winter with the steam
The following paragraphs came to us
in it, or try a ground
a few days ago from Mr. Robert Brock,
rod driven directly
of Wallace, Idaho, and express vividly the
into the soil. A small
of
radio
as
a
value
to
great
companion
fixed condenser of say
those in lonely places.
THE EDITOR.
microfarad,
.001
This is written from a lonesome eagle's nest
in the heart of the Coeur d'Alene National
Forest.
The spot is the Sunset Fire Lookout
Station.
have been up here since June 5th,
seeing practically no one in all that time
I
yet
best
am
I
placed between the
ground wire and the
ground binding post
1
My
not alone.
radio outfit
is
of the set
could have.
hear concerts from Los
Every night
Altos, San Francisco, and Sunnyvale, California, Portland, Oregon, and Seattle, Washhear the teleBeside the concerts,
ington.
phone conversations between Los Angeles
and Santa Catalina Island, and every noon the
company
I
signals readily.
Those who have
ground space "available will find a
counterpoise" of great
value, both from the
point of view of abso-
time signals from San Diego. Using my large
honeycomb coils, the world's news is at my
finger tips.
hard to realize the great value of radio
isolated as
am. It is indeed wonderful to hear so clearly music played five
hundred or a thousand miles away. It was a
It is
lutely eliminating
I
ground
and
had when brought my
lucky thought that
It is the most valuable
set along with me.
part of my equipment.
disturbances
also in increasing
the selectivity or ability of the set to tune
I
I
it still
through the radio
lets
I
man
quite ef-
car noises while
I
to a
is
fective in keeping out
power-line or street-
the
sjharply to desired
Such a
cause
ficulty
removal of some
a great difference.
signals.
counterpoise
consists
so little dif-
virtually of a second aerial of three or four
should be experienced in getting the
wires spaced some six feet apart and running
Preferably
parallel to and under the antenna.
they should be kept off the ground by insulators, the same as the aerial; but weather-proof
owner of such a motor to
itself,
assist in
remedying
the trouble. The faulty motor will be found
to be sparking badly.
This indicates bad
"commutator" adjustment on the motor or
even worse, perhaps a burned out section. If
allowed to continue, this will greatly injure
the motor.
There are other methods of reducing interference from such causes such as placing electric
condensers across the wire connections to the
motor. This involves expense and careful
testing, however, and if disturbances continue
from such causes, it is better to move your
wires laid on the ground will give quite satisfactory results.
The set, with no ground or aerial connected,
should be perfectly quiet. To obtain this
condition in a commercial marine receiving
station where very long distance work is accomplished, extreme quietness has been ob-
by shielding the
tained
copper-lined
This
is
more
iron
boxes
feasible
of
sets
completely in
batteries
course
and
all.
when dry-
King Electron Reduces Interference
313
battery tube sets are used. The radio connoisseur will find his time
well
in
repaid
such
building
a
wooden box
lined with roofing tin
copper, with lined front
or with
doors to the box as well, so that the
set may be closed in completely for
Even
the last word in refinement.
the loud-speaker may be kept within
the box to ad vantage, with a screened
opening to let out the sound.
X-Ray Machines. There is no
known remedy for removing the in-
GROUND
from an X-Ray machine
except getting far enough away from
it, or shielding the machine itself.
Smoke Precipitators. A bad cause of interfence is a high-voltage smoke stack equipment.
The difficulty is greatly reduced if the owners
can be persuaded to shield the high-voltage
lead to the smoke stack with a grounded metal
A METAL-LINED BOX
terference
screen.
This also acts as a safety screen
the factory, so
it
will serve
in
two purposes.
Before deciding that in-
Interference Check.
comes from any outside source, it
well to check up with someone else in the
terference
is
vicinity to see
ficulties.
It is
if
he
is
well to
experiencing similar difremember too, that few
the broadcast transmitters can yet
00% continuous service and quality.
of
1
give
which the entire set is housed, is of considerable help in keeping out stray electrons
In
ners are
somewhat more
difficult
to adjust,
but permit very much better tuning. As a
matter of fact, loose coupling may be accomThe shortplished with single-circuit tuners.
ened aerial is a step in this direction.
To carry the idea further, disconnect the
single-circuit tuner from the aerial and ground
completely. The aerial and ground are then
connected to the two ends of a simple twentyThis coil may be of any
five to fifty-turn coil.
standard design for radio purposes such as the
basket-wound coils or the cobweb type. This
coil is then placed near the tuning coil of the
single-circuit tuner, say on the cover of the box.
Wavelength interferInterference.
by far the most common source of
trouble on cool winter nights when long ranges
are possible. The first steps will be the same as
The
those already given, a perfectly quiet set with
posts, and the first extra aerial coil brought near
this second one, the second will pick up the en-
Radio
ence
is
no ground and no
Short Aerials.
aerial.
The
first
and perhaps sim-
of reducing interference between
plest
stations of various wavelengths is to shorten
method
the aerial wire.
antenna
During the winter months, an
fifty to seventy-five feet
long will give
plenty of received energy to the set. With
such a short aerial, the tuning in the set will
be greatly improved. With a long aerial, the
tuner cannot change the wavelength of the
complete circuit of aerial, tuner, and ground
very much. The tail cannot wag the dog,
With the short aerial, the
in other words.
tuning is largely in the tuner and much greater
selection
is
possible.
Some
radio fans will like
have two antennas, a short one to get selectivity, and a long one to get the weaker
signals when local stations do not interfere.
to
Most of the tuners are of
Loose Coupling.
Double-circuit tuthe single-circuit variety.
aerial or antenna and "ground" binding
posts of the tuner are connected together by a
short piece of wire.
Or, if another small coil
is connected between these same two binding
ergy from the first, and with the receiver actually loose coupled it will be found by trial that
the tuning will be much sharper. As skill is
obtained in the adjustments, it will be found
possible to have the extra aerial coil quite a
distance from the tuner coil.
To make this arrangement a complete
double-circuit tuner, it is now only necessary
to add a variable condenser between the first
The variable
extra aerial coil and the ground.
condenser should have a maximum value of
about .0005 microfarads. This will make it
possible to tune the aerial-coil-condenser-
ground
and conand the single-
circuit to the desired signals,
stitutes the
"primary"
circuit;
now picks up the energy
the "secondary" circuit of the combination.
By varying the position of the extra coils the
circuit
tuner which
is
"coupling"
is
adjusted.
Radio Broadcast
In place of the extra aerial coil and condenser, another single-circuit tuner may well
be used.
By this arrangement, one tuner is
connected to the antenna and ground, and its
detector and any other attachments are comThis extra tuner is then
pletely disconnected.
second
tuner which has no
close
to
the
brought
direct antenna or ground connection but has
its antenna and ground binding posts connected together as explained before and will
act
on
ceivers.
regular detector and telephone reBy adjusting the two sets, the desired
its
be picked up, and as the two sets
farther and farther apart, the
of
the tuning will be greatly insharpening
creased although there will also be a diminishAny two
ing of the strength of the signals.
tuners may be used for this double arrangement. Most fans have a simple set with which
they started operations which may well be
used for the first, and their amplifier set will
do very nicely for the second. The simple
tuner consists of nothing but a coil and a condenser in series with the antenna and the
signals
are
may
moved
Loop Receivers. As a further means of reducing interference, there is the loop aerial.
The signals which are coming in a direction in
a plane with that of the loop that is, "end
on," not "broadside" will be the loudest.
This is because the oncoming waves will create
electromagnetic charges of slightly different
potential in each side of the loop, and the
amplifier is used to make the most of these
Almost any form of loop will give
turns of wire around a yardsquare frame will be about right for broadcast
differences.
results.
Six
The tuning of such a loop is accomplished by means of a single condenser
reception.
placed across the two wire terminals of the
six turns.
This condenser should have a maxivalue of about .0005 microfarads. The
same two terminals which connect to the condenser are also connected directly to the tube
mum
set.
Naturally, the loop cannot be expected to
much energy. As a result, a loop receiver will not be of much value except on an
collect
ground.
amplifier set. And
cation is in order.
Such double-tuning arrangements are best
applied to tube sets in which the amplifier
menter who has conquered ordinary audio
tubes
make up
for the loss in signal energy.
is by all odds the best means
Sharp tuning
for reducing interference of
all
kinds.
Good
ground connections, good insulation of the
aerial, and good wire conductors at all points
help the sharpness of this tuning.
Regeneration also sharpens the tuning, particularly in
high-resistance circuits.
Radio-frequency amplification.
amplification,
may
amplification.
The
well
try
circuits
same except that a special
transformer must be used.
The
amplifi-
experi-
radio-frequency
are exactly the
radio-frequency
For radio-frequency amplification, the electrons have to shoot back and forth at very high
rates of change in the tubes.
And the capacity
of the tube to hold the electrons on its surfaces,
regardless of the ordinary action of the electrons out from the filament, has a very important effect on the amplification.
If the electrons can rush in and out of the tube easily,
LOOP ANTENNA
It
radio-frequency
A LOOP ANTENNA MAKES FOR REDUCED INTERFERENCE
much energy as an outdoor antenna, however, and needs an amplifier
does not collect so
to help
it
out.
King Electron Reduces Interference
will do little real work in the way of
giving amplification. As the "impedance" or
reaction to their intrusions is increased, the
force they will develop as electric pressure or
they
be increased to a point where it will
do useful work. Fortunately, this is readily
accomplished by making the grid of the tube
voltage will
more negative than
usual.
By
this
is
meant
the average electric condition of the grid, before any action due to radio signals
Under these average condistarts.
tions, the grid is made to have a
concentration of electrons on it.
This is determined in turn by the
number of electrons on the part of
the circuit to which it is connected.
The first grid is connected directly
to the loop aerial or antenna. The
other end of this loop is connected
If it is connected
to the filament.
to the side of the filament which is
directly connected to the negative
side of the filament battery, the
whole arrangement
will react
back
the House that Jack Built to
make the grid negative; the whole
loop and the grid as well will have
the same negative condition as the negative side
of the filament which means a large number of
Under these conelectrons already on them.
ditions it may be said that the capacity of the
And
grid is already pretty well used up.
it
no
electrons
are
to
more
practically
going
from the filament inside the tube. Likewise
the plate current inside the tube is greatly
decreased.
Therefore with very few active
electrons passing in the tube, the resistance
between the filament and grid is likewise
So the "impedance" of the
greatly increased.
grid to a further rush of electrons produced by
radio signals will be high.
The whole action of the radio-frequency amplification starts in the development of rushing
electrons in the loop in step with the oncoming
If this rush happens at a certain insignals.
stant to be in such a direction that the side
connected to the grid receives a rush of electrons, even though only a relatively few get
on the grid, these intruders will produce a comparatively large change in the grid voltage.
This will in turn decrease the plate current in
the output of that tube to a greater degree as
has been described by King Electron in preThis plate current decreases
vious accounts.
through the primary coil of a coupling translike
315
former to which it leads directly. This transformer consists of two windings, the first or
primary connected between the plate battery
first tube; and a secondary
close
to the primary, and convery
winding
nected between the grid of the next tube and
back to the negative side of the filament of
this
second tube. For exactly the same
reasons as given before, for the back connection
and the plate of the
T
Radio Broadcast
316
necessary to add small extra dry batteries between the secondary of the transformers and
These are
the negative filament of the tube.
"C"
The
positive side of
these batteries will be connected to the negacalled
batteries.
tive side of the filament, and the negative side
of these batteries will be connected to the back
end of the transformer secondary. This extra
negative action will push even more electrons
through the transformers into the grids of the
connected tubes. These extra batteries need
only be very small the kind used in flash-
The two-cell
lights.
or three-volt type will gen-
erally be sufficient, but it is well to have some
three-cell (4.5 volt) ones for trial. The current
which they take is practically nothing, so their
be that of their ordinary deterioration.
A more adjustable arrangement which will
make a radio-frequency outfit cover a wide
life will
range of frequencies or wavelengths is provided
by the use of "potentiometers." These potentiometers are high resistances placed across
the filament battery. A sliding contact on such
a resistance is connected to the back connection
of the transformer Which carries the electrons
v
back to the grid. As this slider is moved
over the resistance, it will take up the electric
5
7
potentials which correspond to electron densi-
to get a smooth variation over the range.
It is
well to put the tube rheostats in the negative
leads from the battery instead of the positive
done with
audio amplification. The
are
potentiometers
directly across the filament
This makes it possible for the conbattery.
nected grids to be more negative than the negaas
is
by the amount of rerheostats, and does
away with the need of any extra "C" batteries.
If the tubes are turned out by using the rheotive side of the filament
sistance in the filament
the potentiometers will still be in circuit,
well to have a main switch to disconnect
the filament battery from the whole set.
This
switch also makes it possible to leave the sepastats,
so
it is
rate rheostats at their best adjustment.
By the use of radio-frequency amplification,
much better results may be accomplished in
the way of selectivity, as the input power may
be reduced to a minimum. Such radio-frequency amplification is of course applicable to
double-tuner sets where loose coupling is arThere is little if any advantage in
ranged.
using radio-frequency amplification on singlecircuit tuners connected directly to an antenna.
As a matter of fact, the radio inspectors have
been doing very careful and helpful work over
the whole country in arranging slight changes
in the wavelength for the broadcasting stations
to eliminate as far as possible any beat-note
along the resistance, and this is the reason
name "potentiometer." This density
will be greatest at the end of the resistance
connected to the negative terminal of the
filament battery; and least at the positive
interference between transmitting sets; and
with equal care in the design and use of the
receiving lay-out good results may now be ob-
end.
tained by the listener-in.
ties
for the
By varying
this, it is
therefore possible
Listen to These
Some
"Inside
port, Iowa;
Dope" on Four More "Stations that Entertain You":
WHN in Ridgewood, Long Island; PWX in Havana,
Los Angeles, California.
HEARD
Davenport,
You Must Be Within Range
Iowa,
last
night,"
says Smith to Jones.
"That's
I On
"
nothing,"
replies
Jones
to
I
"You
don't say!"
crushed, impressed, and interested.
"
Sure but of course you've got to know how
Smith
fishy,
and
At Least One
fish stories
less like facts are reeled off
get Havana 'most every night.
one tube, too."
Smith,
sound
of
WOC in Daven-
Cuba; and
is
to tune your set.
You can't just sit in front
of it and twirl the dials around, in the hope
that some far-away stations will speak up.
Now, for instance, when start in to tune
And they're off in a cloud of dust. Facts
I
that
KHJ
of
in
Them
that sound
more or
with equal glibness
and solemnity.
Judging from the lists that have been sent to
RADIO BROADCAST in the " How Far Have You
Heard on One Tube?" contest, however, the
midnight radio anglers are making the most of
their opportunities during this "open season."
The four stations shown this month have
widely different geographical locations, representing the Atlantic Coast, the Pacific Coast,
the east central part of the United States, and
the territory beyond our southern boundaries.
'WHERE THE WEST BEGINS AND THE TALL CORN GROWS"
The
stuffed birds hovering near the ceiling,. the bits of wisdom stenciled on the walls, and the "rustic" furnishings give
this music studio of the Palmer School of Chiropractic in Davenport, Iowa, an unusual appearance, to
say the least
THE ATTRACTIVE STUDIO AT WHN, A LOW-POWERED STATION AT RIDGEWOOD,
THE IMMACULATE OPERATING ROOM AT PWX, HAVANA, CUBA
L.
I.
OPERATING ROOM AT THE LOS ANGELES
TIMES
STATION
Litzendraht vs. Solid Wire
By RALPH
Engineering
of a
Staff,
a special cable composed
of strands of fine in-
number
has long held the
wire,
reputation of giving lower losses
with radio-frequency currents than
any other type of wire. The statement is not
without foundation, for in most cases coils of
high grade Litzendraht may show a five to
fifty per cent, decrease in resistance, compared
sulated
EENDRAHT,
to solid wire,
On
test,
it
strands are perfect.
has been found that a coil
if all the
em-
ploying litzendraht may act perfectly for six
months or a year, and then develop troubles
which indicate a broken strand or so in the
cable with which the coils are wound.
This
often occurs, no matter how carefully the
manufactured, mounted and tested,
although it does not make the set inoperative
and would pass unnoticed by many users.
Manufacturers who are intent on satisfying
the most discriminating amateur have investigated all factors which cause excessive
coils are
resistance in litzendraht coils.
R.
BATCHER
Western Electric Company
Recent experiments have shown that solid
copper (No. 25 B. & S.) with one layer of cotton
and one of silk, is equivalent to the litzendraht
used (20 strands of No. 38). Complete
measurements were made on equivalent coils
so that a direct comparison might be made.
To make sure that there were no broken
strands to begin with in the litzendraht, each
strand was tested for continuity separately,
stripped of enamel and separately tinned.
Upon soldering, the complete direct-current
resistance of the cable was measured and
checked with the theoretical resistance. When
tests were completed on this coil, one strand was
intentionally broken at one end and the tests
repeated, after which another wire
was broken
at the opposite end.
The
It
first was a practical test in a receiver.
was found that the solid wire coils will
oscillate (for c
w
reception) with the filament
current just as low as when the perfect stranded
wire coil was used. This test was thought to
represent actual receiving conditions.
Radio Broadcast
320
The high-frequency resistance was
With ordinary methods
ured.
next meas-
of measuring
impossible to
high-frequency resistance, it is
separate the resistance from the impedance,
and as the measurements were made at frequencies very near the natural period of the
coil, the resistance was apparently greatly increased at the higher frequencies.
The reason
for this will be taken up later.
A graphical presentation of the results is
shown on the accompanying graph. Curve
"A" represents the apparent resistance of the
coil wound with litzendraht in which each
strand was tested and found perfect, and perfect
connection made with each strand at each end.
"
"
Curve B shows the apparent resistance for
the similar coil wound with solid wire.
Curve
"C" shows the same coil as used in "A" with
one strand purposely broken near one end.
It will be seen that Coil "A" has the lowest
resistance.
"B"
Strictly speaking, however, Curve
moved 25 meters to the left in
should be
order that direct comparisons may be made, as
it happened that in this case the solid wire coil
had a natural wavelength 25 meters higher
FREQUENCY
8
(CYCLES)
o
o
than the litzendraht
relatively small and
number
coil.
may
This difference is
be due to any of a
of reasons.
Curve
"C"
has several outstanding features:
capacity has increased apto
about
four times its original value,
parently
since the natural period is about doubled.
There is also another frequency lower than
the fundamental, at which the resistance inthe
distributed
creases.
Another strand was broken, this time at the
end opposite the first break. The result was
that the coil seemed to respond slightly to
several wavelengths other than its natural one,
giving a curious effect in tuning and being very
poorly adapted for precise work in a regenerative receiver.
The apparently high resistance shown on
the curves at the lower wavelengths may surThat these
prise some radio experimenters.
results are logical may be shown by the fact
that theoretically a coil has infinite impedance
at a frequency corresponding to its natural
wavelengths. In fact, any inductance shunted
by a condenser (in this case it is shunted by
the distributed capacity) will act as a very
high impedance to frequencies at and near the
natural or resonant frequency of the combina-
700
tion.
600
fact that a large part of this apparent resistance
at such frequencies is due to the reactance, and
We
can, however, console ourselves
by the
so will not absorb energy and produce heat as a
real, resistance would.
The method used for
measuring the above resistance was to couple
the coil very loosely to a vacuum-tube oscil-
500
4.00
300
\
200
\c
\
100
\A
A
thermo-couple, condenser (variable,
having negligible losses) and a high-frequency
resistance box made up the rest of the circuit
with the coil. The change in the deflection of
the galvanometer across the thermo-couple
was noted when resistance was added to the
circuit and the coil resistance computed from
such data.
The problem then resolves itself into choosing the lesser of two evils.
Laboratory measlator.
\
urements show litzendraht superior as long
it is in good condition.
Actual tests in a
receiver show apparently no difference as far
as sharpness of tuning is concerned or for its
It is bequalities in an oscillating circuit.
as
lieved that the desire to safeguard the user
WAVE LENGTH
from the freakish effects of broken strands is
enough to throw the balance over in favor of
solid wire.
Simple Bulb Transmitters
By ZEH
BOUCK
PART IV
Alternating Current Systems
TUBE transmitters are classified,
according to the characteristics of
the plate supply, as rectified or
A^.
self- rectified
sets.
In
rectification
the iio-volt alternating
transformed to an adequate plate
systems,
current
is
and passed through rectifying apit is changed to direct current.
where
paratus
potential,
It is
then
month
filtered in the
manner described
last
output of a motor-generator,
and finally applied to the plates of vacuum
tubes, the oscillating output of which may be
modulated at voice frequencies for the transRadio telephony is thus
mission of speech.
simplified to the extent that all power may be
.obtained from a single electric light socket.
At the same time the noise and moving parts of
the motor-generator are eliminated. A. C.
for the
radio telephones generally represent a less
formidable initial expenditure, and when properly and intelligently operated, give results
comparable to those secured with a motor-
generator.
Self or unrectified sets employ the "raw,"
stepped-up A. G. as the plate potential, without modifying it by filters or similar apparatus.
The
three progressions
the alternating current
fluctuations in the power transformer, the resulting variation of the plate charge, and the
accompanying effect on the oscillating output.
If two oscillating tubes are used in a selfrectifying circuit, the plates being supplied
from the opposite terminals of the transformer
(one of which is always positive), each tube
will operate on the opposing half of the cycle,
plain
rectification.
indicate, respectively,
giving a more smooth and powerful wave.
radiated output of the second tube, which
The
really the complement of the first, is indicated by the dotted oscillations in Fig. i. The
frequency of the combined oscillations is, of
course, double that of the single bulb, and a
far more pleasing tone.
Utilizing both halves
of the cycle in this manner is often referred to
as full wave self-rectification.
is
Attempts have been made to adapt
full
self-rectification to the transmission of
and music, but
wave
speech
knowledge of the author,
experiments in this direction have been only
For radio telephony,
successful.
partially
to the
This system has become especially popular
with amateur stations working distance, where
it solves the problem of an economical, high-
power C. W. transmitter.
As any one terminal of an alternating current
supply is positive for half an alternation, it is
capable,
during
that
time,
of
supplying a
vacuum-tube plate with the current essential
to oscillations.
Such circuits are "self-rectiin the sense that the tubes automatithe positive fluctuation of the current,
use
cally
and cease to take current or oscillate when the
terminal feeding the plate is negatively
Bearing in mind that a flow of
charged.
electrons constitutes a plate current (which is
necessary for oscillations), and that electrons,
fying"
being negative, are repelled by a like charge,
will clarify the phenomenon of self and
Fig.
i
FIG.
i
operated from an A. C. source, separate rectification must be employed.
This is commonly accomplished by either of
two methods, bulb or chemical rectification.
Radio Broadcast
322
The
latter
is
the more economical system, but
requires considerable experimentation
As explained
before success is achieved.
in only
will
current
an
audion
a
above,
pass
often
one direction, from plate to filament, the
phenomenon on which bulb rectification is
dependent. The grid does not function in this
and rectifying tubes are generally
with only two elements, the plate and
operation,
built
filament.
A typical bulb rectification circuit is indicated as that part of Fig. 3 enclosed in dotted
lines.
P is the primary of a transformer designed to operate on 1 10 volts, 6o-cycle current.
R. F. is a secondary winding giving eight volts
across the outside terminals, and supplying
P. F.
current to the rectifying tube filaments.
an eight-volt filament winding, and
5-watt power tubes. Though this
last winding is indicated as a part of the power
transformer, it is often desirable to wind it as
a single secondary on a separate transformer,
is
likewise
lights the
such as described in the January RADIO BROADS is the high-voltage secondary, giving
CAST.
iioo volts between terminals X and X'. All
secondaries are tapped in the middle.
The
centre tap
Y
is
always negative
in re-
spect to the positive terminal of the highvoltage secondary, a charge that alternates
between X and X'; and is therefore the negative
high-voltage lead. When X is positive, a
current passes through rectifying tube number
one, the filament of which (or terminal Z) is
In the
charged positively in respect to Y.
next fraction of a second, conditions are reversed, and X' is now the positive terminal of
secondary S. Tube one, with the plate negative, ceases to function (Cf. Fig. i) while bulb
two passes a current; positive electricity again
being drawn from Z. Thus Z, which is plus
regardless of current alternations, supplies the
positive potential to the plates of the power
tubes.
As only half the transformer secondary (550 volts, between the terminals and the
centre tap) is applied to the radiophone circuit, and allowing for a voltage drop through
rectification, the plate potential will approximate 400 volts, the general working voltage for
5-watt tubes. The plate voltage may be further decreased, in order to reduce power, by
However, the
lowering the rectifier filaments.
voltage should not be dropped more than 50
to 75 volts in this manner, as the A. C. hum is
likely to be emphasized when the rectifying
FIG. 2
Material for a 5-watt rectified, radio telephone transmitter, using two rectifying tubes and two power bulbs
Simple Bulb Transmitters
323
FIG. 3
The circuit used with
is
tubes
are
burned
This system
the equipment shown in Fig. 2.
fundamentally the Colpitts oscillator with Heising modulation
below their normal
bril-
liancy.
The special transformer for rectification is
best purchased, but the intrepid experimenter
may build his own/ following the general
procedure outlined in the preceding issue of
RADIO BROADCAST for the construction of
The core
a filament lighting transformer.
should be built up two inches high in the same
manner, using 10" x 2" soft iron strips. The
exact dimension of the core may be varied as
occasion necessitates, but the cross-section must
in all cases approximate four square inches. The
secondaries are best wound on three legs of the
Care must be taken to insulate
transformer.
the four windings for 1100 volts, and empire
cloth or tape should be used generously.
The primary is wound with 300 turns of
is indicated in Fig. 3, and is fundamentally the Colpitts oscillator with Heising modu-
circuit
lation, the operation and values of which were
described in detail in the January number.
Tuning and the adjustments of the modulating
circuit are effected in the same manner as was
suggested for the D. C. apparatus. The substitution of rectified A. C. for the motorgenerator, necessitates no change in the constructional details, excepting the chokes Xi
and X2, and the condenser Ci and C2. These
chokes and condensers constitute the filter
system, and as the ripple a'ccompanying rectiis more difficult to eliminate than the
comparatively gentle hum of a D. C. generator,
they must be of larger sizes. The reactance
coils (chokes) are each wound with three
pounds of No. 27 single cotton covered wire,
fication
The two
15 single cotton covered wire.
filament lighting secondaries are each wound to
24 turns with No. 9 single cotton covered wire;
and the high-voltage secondary with 3000 turns
on lo-inch cores with cross sections of approximately three square inches. Ci and C2
should have a combined capacity of at least
ten microfarads.
C3 and C4 are capacities
The
similar to those shunting the filament lighting
No.
of
No. 27 double cotton covered wire.
wound
two
or
the
the
same
in
direction)
pies (both windings
finish of the first pie connecting to the first turn
on the second, and the joint brought out for
the centre tap.
Every other layer of the highvoltage secondary should be insulated with a
single covering of empire cloth or tape.
The various units used in the construction of
a bulb rectifying set are shown in Fig. 2. The
secondaries
are
in
sections
;
transformer
the motor-generator installation,
paper-foil condensers such as are
in
and may be
used across spark-coil vibrators.
ELECTROLYTIC RECTIFIERS
ECTIFICATION
chemical
action
of
different
which, when
is
rectifier
accomplished
by
the
is
a
on aluminum
used as an electrode,
solutions
that metal
in
electrolytic
Radio Broadcast
324
permit electricity to pass through it in
only one direction.
The chemical rectifier is much cheaper than
the bulb system, and its installation, exclusive
of the transformer, should not exceed three
The rectifier is constructed in the
dollars.
will
form of small jars, the number and size depending on the current which they are to pass.
The jars are best built in a rack after the
"
fashion of a storage "B battery, and a twentyjar set of the jelly glass variety will adequately
handle the plate current for a 5-watt set. The
electrodes are of lead and aluminum strips,
one inch wide, three inches long, and one
Each jar contains
sixteenth of an inch thick.
one lead and one aluminum plate, separated
by thin blocks of hard rubber, the whole being
bound into a compact unit with rubber bands
One
corner of the aluminum plate
is drilled, and a brass nut and bolt passed
through the hole and tightened over a short
length of copper wire lead. The twenty jars
are broken up into groups of ten in series, the
wire on each aluminum electrode being soldered
The active eleto an adjacent lead plate.
ments (aluminum) at the end of the two series
are joined, a connection that forms the positive
lead, while the lead plates are connected individually to the terminals of the high-voltage
secondary, the centre tap of which is again
(Fig. 4).
be obtained from Eimer and
may
purpose,
Amand, 240 West 42nd
Street,
New York
City.
Several electrolytes are in common use, but
the most satisfactory solution is probably made
by mixing six ounces of pure phosphoric acid to
one quart of distilled water. The best grade of
ammonia is then added until the mixture tests
neutral with litmus paper.
After the mixture
has cooled, ammonia is again added in small
quantities, until there is just sufficient to turn
the litmus paper blue, i. e., the solution is
slightly alkaline.
impossible to obtain phosphoric
be replaced by boric acid, of which
a saturated solution is formed with distilled
water.
In accomplishing this, it is best to
heat the water, and stir in the boric acid until
If
acid,
it
is
it
may
no more will be dissolved. On cooling, a
portion of the acid will crystallize, indicating
that the solution is truly saturated.
Ammonia is added as before, until the electrolyte
tests alkaline.
The
solution for
all jars
must be made at one
time, in a single receptacle, and poured into the
cells until an inch and a half of the plates is
covered. The rectifier is then ready for use,
and
made
part of the Colpitts circuit by
the
wires A and B (Fig. 5) to the
connecting
correspondingly lettered leads in Fig. 3.
is
experimenters employ an electrolyte
saturated solution of borax.
Many
consisting of a
This
MJBBER
BANDS
made by
dissolving as far as possible a
of
a
ten-cent
portion
package of 2o-Mule-Team
Borax in one quart of distilled water. While
this
tion,
is
is
cheaper than the phosphoric acid solu-
and obviates the litmus
necessary
rectifier
to
will
"form" the
operate.
by subjecting the
first for a minute
-ALUMINUM
HARD -RUBBER
BLOCK"
FIG.
negative (Fig. 5).
identical with thai
4
The transformer may be
used
in bulb rectification
except that the rectifier filament winding is
eliminated.
Care must be taken in securing the
aluminum, as the success of the rectifier is directly dependent on the purity of the metal.
Aluminum
sheet, especially
"formed"
for this
This
testing,
plates
is
it
is
before the
accomplished
the high potential,
at a time, then gradually increasing the period until the transformer
secondary ceases to heat under the load.
During the preliminaries, until the plates are
rectifier to
formed, the jars are virtually a short-circuit.
When the rectifier is working properly, there
is generally a gentle glow about the aluminum
plates, and the temperature rise in the solution,
or transformer secondary, if any, should be
There should be no pyrobarely perceptible.
technics, and the presence of such is indicative
of overloading, which may be remedied by
adding more solution or increasing the number
of jars.
Electrolytic rectification is an interesting
and instructive experiment, and so cheap a one,
Simple Bulb Transmitters
325
that the experience of building even an unsuccessful rectifier is well worth the cost.
If
the experimenter is at present transmitting on
boiled down to essentials, and the set is operated altogether from power supplied by a
single A. C. lamp socket.
a small B battery radiophone, such as has been
previously described, he is advised to adapt it
to electrolytic rectification, following out the
socket, the
Excepting for the rheostat, microphone, bulb,
^ooo-ohm grid-leak, Cj, C4 and
If the amateur has
C5, the set is home-made.
the construction of any of these
still further reduced.
Inductance Li is wound with 40 turns
of any convenient insulated wire under No. 22
and tapped every fourth turn. L2 is a single
turn of wire wound over Li. Ci is a fixed
capacity of three to eight plates (to be defacilities for
items, the cost of the set will be
termined by experiment) of one by 3-inch tinfoil (two square inches active area) separated
by mica. Gz is similar to Ci, using however,
X has already been
only two or three plates.
described,
and 03 may vary from two to ten
the higher capacities being deC<=, will probably cost the experimenter nothing, but in advent of his inability to obtain the spark-coil vibrator conmicrofarads,
sirable.
FIG. 5
principles
demonstrated in applying
this sys-
tem
to the originally direct-current Colpitts
circuit.
Indeed, it would be well to construct
especially, a 5-watt set of simplified design, in
order to become familiar with the characteristics of rectified
to build
operation, before attempting
is
SUCH
twenty-five dollars!
wound
to 2500 turns, a reduction that perdown of the rectifier to sixteen
A
radiation
ammeter should be borrowed
for tuning the set.
Tuning and operating
for
The apparatus has been
the
is
done as suggested
in the January
D. C. installation
RADIO BROADCAST.
110
TRANSF.
FIG.
Diagram
of a 5-watt set, operated
,
former from that designed for the Heising
modulation set exists in the secondary S, which
jars.
indicated diagrammatically in Fig. 6, and the cost of
the various parts should not total more than
installation
.
mits the cutting
AN EXPERIMENTAL 5-WATT SET
an
densers, telephone shunt capacities of .002 5 mfd
used for receiving purposes, may be substituted.
The only variation in the rectification trans-
is
more complex apparatus.
C4 and
6
by power from a
single A. C.
lamp socket
VOLTS
Cave-Man
Stuff,
But
It
Works
A Rough
but Ready Outfit that Gives Excellent Results on One Tube.
Pointers on the Delicate Art of Bringing in Long-Distance Stations
Some
By
THE
TANNEHILL
R.
I.
phones cost $4.37 and
circuit,
my vernier condenser,
the pride of my outfit, was made from the
was
plates of a knock-down condenser that
INsubject
never able to assemble as directed. The knob
on the condenser is one of my wife's clothes
average discussion of the single-
single-tube, regenerative receiver,
the writer starts off with the single circuit
but is unable to confine his remarks to the
and introduces a
vast
hash
1
of
selectivity, inductively coupled circuits, variometers, electrons, loop aerials, and radio-
pins.
From
the above remarks you can readily see
have never
a first-class "ham".
The only time tried
soldered a connection.
single circuit is less selective, but the average
it I
succeeded in
beginner finds any
of
radio
receiver
making
nothing but
type
a lot of smoke. Every
"The listener who does not occasionally hear
so selective that he
time the wind blows
stations farther away than 500 miles," says
has trouble hearing
the author of this article, "is either in a dead
am afraid my aerial
at
all.
Hence
anything
zone or is not acquainted with his apparatus.
will fall down.
Yet
trouble him with
It
frequency amplification.
may
be that the
that
am
1
1
1
I
why
methods
If he tunes his set systematically instead of
turning the knobs in a haphazard manner with
the hope of accidentally hitting an adjustment,
he will get results. The directions herewith
may not conform with the practices of the
manufacturers of apparatus, but manufac-
of tuning out
interference?
Confidentially,
lieve that
1
be-
every one of
these writers
is
guilty
the
of
v,ariometer
habit and that his cel-
do not guarantee any great ranges and
furthermore do not furnish directions with the
apparatus that would enable anyone to get
lar or attic conceals a
of parts that
not fit into a single
do
Have any
circuit.
them
great ranges.
directions with
conscientiously
so,
claim that
it
two stages
two
they
of
and practically
pill
of
have
I
with this outfit give
an aggregate mileage
of
1,950.
In every instance
1
found by making
I
in-
quiries that others in
town had heard the
same stations on simTherefore
it
has
been termed, was not
due to the set but
perhaps to atmosilar
sets.
the
freak,
as
pheric conditions.
I
As
confeel sure that
far as the freak
cerned,
audio
a,nd
amplification to pick
distant?
pages
hesitate to endorse his practice of
never soldering a connection; but he does get
The method of tuning described in
results.
this article should help many set-owners to
improve their receiving records. THE EDITOR.
requires
of radio
of
liver
thirteen
we should
single circuit?
why do
a
get
Mr. Tannehill's home-made equipment may lack finish and compactness, and
Some
ployed the single tube
If
You
nothing with a radio receiver!"
of
and consistently emand the
of
tions
turers
number
the staheard
fourteen
is
was about 50 per
atmosphere and 50 per cent, careful and
it
up a
station 200 miles
cent,
patient tuning.
have for one year employed the single
in a single circuit more than any
other type of receiving apparatus.
Located in
southeastern Texas, the home of static,
have
frequently heard stations ,000 miles away and
for long-distance reception
would have
2, 3-plate
$2); Ci, .001 mfd. ($4);
3; C^, .00025
grid leak, combined with
mfd.; S, tuning coil (250. to make); R, tickler coil
.001 mfd.
(25C.) G, ground to water pipe; 4, approx.
rheostat
to
volts
R,
B,
($1.50
$3);
22.5
(35C.);T, ($5);
(about 75C.); VT, tube (#5 to $8).
nothing in preference to a single-tube, singlecircuit receiver.
aerial is fifty feet long,
The tuner may be
can be purchased for
A cheaper and really
cedure is to cut two
I
vacuum tube
I
i
I
My
one end tied to the chimney and the other to
a two-by-four nailed to an outhouse.
My
A
(cost
i
($3);
GL,
;
Parts
a variocoupler.
about $1.50 to $2.00.
more satisfactory pronarrow rings from a
Cave-Man
Stuff,
cardboard tube. Wind fifty turns of No. 26
No. 28 wire around one, tie the ends
around the rings, and leave about a foot or
more of wire at each end for connections.
Around the other wind about sixty turns and
or
same way leaving leads for connections.
Screw two curtain pole brackets
into the end of the table, lay a piece of broom
pole across them and hang the two coils on the
secure in the
But
It
Works
327
with the usual hook-up.
In that
case increase the grid condenser to .001 by
oscillate
substituting a fixed condenser of that capacity.
You may use the one shunted across the tele-
phones for the grid and replace the phone condenser with one of about .0005 mfd. capacity,
also fixed.
Oscillation will usually be obtained
with a relatively low filament current with these
latter capacities.
However, do not
Set four binding posts
pole (see photo, p. 329).
into the edge of the table and fasten these four
coil leads between the bolt head and washer of
fail
to try
it
with the rotor
the binding post, leaving the binding post for
other connections unless you wish to tie more
than one wire into the clamp of the post. This
tuner is very satisfactory and will cost about
Use the 5o-turn coil for a
50 cents to 75 cents.
tickler
and the 6o-turn
testing the set
coil for a tuner.
you may
find that there
After
too
is
much wire on the tuner, in which case remove
a few turns at a time while testing.
Connect the other apparatus as shown in the
diagram.
Increase the brilliancy of your
fila-
ment until a slight hiss is heard. Decrease it
till you are
Do
just below the hissing point.
this with your two coils at extreme ends of the
pole or with
Rotate your conBring the coils together.
denser plates and you may hear the tube osThe oscillation of the tube usually
cillating.
takes place more easily at the low capacity
end of the condenser, or in other words with
the condenser nearly open.
This is the primary consideration for the
beginner if he must tune in long distance stations.
The tube must oscillate with the coils
close together.
When the tube is oscillating
there
is
a
MR. TANNEHILL/S SINGLE-CIRCUIT HOOK-UP
rotor of variocoupler vertical.
mushy sound
in the receivers,
some-
With which he has heard stations
over 1,000 miles away, with one tube
inverted (or with the coils reversed). Once
you have learned how to produce the oscillations it is but a short time until you have
learned to control them by changing the filament brilliancy or turning the rotor, or if
coils are used, by moving one of them back
and forth on the pole.
Occasionally there
is
almost a total absence
of static, spark signals, or other sound, so that
it is nearly impossible to determine whether
thing like a faint rushing of air. The static
noises become louder as the point of oscillation
is approached either by
turning the condenser
or moving one of the coils back and forth.
or not the tube is oscillating.
This is rare,
however, at the present time when there are
heard, will usually be clear
less
musical with the tube
The second step is to tune in a telephone
station.
With the tube oscillating, turn the
but become hissing noises when
the tube is oscillating.
If the tube does not oscillate under this
test, then turn one of the coils around and try
it
Instead of turning a coil around you
again.
may exchange the two connections to one of
the coils. If you are using a variocoupler, make
the test with the rotary coil horizontal and if
you do not hear the tube oscillating, turn the
rotor completely over and try again.
Occasionally you get a tube that does not
condenser around very slowly and listen for a
This is the carrier wave of the
whistling note.
broadcasting station. As you change the condenser capacity you come upon a high-pitched
whistle.
As you turn further the pitch of the
whistle becomes lower and lower.
As you
turn on, the whistle repeats itself becoming
Spark signals,
and more or
quiescent,
if
so
many
broadcasting stations and amateurs.
higher and higher
At the centre of
in pitch until it disappears.
this double wave you will
If you do not
perhaps hear music or voice.
hear the carrier wave, separate your coils
Radio Broadcast
328
slightly or reduce the filament or incline the
If this test does
rotor slightly and try again.
not produce a carrier wave, then remove a few
turns from the tuner coil or try another tap on
the stationary coil of your variocoupler (if
With the
the latter is used), and try again.
in
antenna
and
a
.001
condenser
ordinary
series as shown in the diagram, the broadcasting
stations should be heard with about 40 to 60
In some cases
turns of wire on the tuner.
you may require only 35 turns.
Turn the condenser slowly, as the broadcasting
when
stations
sharp tuning
any
you have obtained an
require very
After
distance.
at
approximate setting with the .001 condenser
you will find that the vernier in shunt with it
on the vernier attachment will give a much
closer setting.
While you are experimenting with this 'set,
your tube will be occasionally in a state of oscillation.
Much has been said about the interference that one creates in tuning a regeneraDon't let that worry you.
tive set.
The
output of a detector tube will not split anybody's
ears.
The fellow who is using four or five
hard tubes in an amplifying circuit is the fellow
who
hears your
the fellow
who
little
wave and usually he
is
the interference
with the tuning of his set.
Let the blame rest
where it belongs on the fellow who is using
five-watt power tubes in his receiving ciris
creating
all
cuit.
you try to tune in a distant station without oscillating you will never get anywhere.
You can pick up that carrier wave a dozen
times easier than you can his music or voice.
Now we shall suppose that you have succeeded in picking up a carrier wave after altering your coils until tuned within the proper
range for broadcasts. At the centre of the
wave you will hear something that bears a
distant resemblance to music or a man's voice
that sounds more like the barking of a dog
than anything "else. Your next problem is
to clear it up and amplify it.
You will now have learned that your hand has
a capacity effect.
While you have your hand
on the condenser dial or knob you hear the
carrier wave, but when you take your hand
away it is gone. Your hand affects .the tuning
by increasing the capacity. You will therefore find that by increasing the capacity of the
condenser till you cannot hear the wave, it
comes in when you take your hand away. By
experience you will learn just about how much
If
capacity effect your hand has and make an
allowance for it.
Then you learn another thing. You have
the carrier wave tuned in at last and now you
seek to clear up the music by inclining the rotor
of your coupler, or by separating the two coils
(if tuning with them), and you find that this
also affects
your tuning.
the coils are close together or. when
the rotor of the coupler is horizontal or nearly
When
so, a slight change in the coupling causes a
decided change in the wavelength of your receiver.
As your tuning coil and tickler coil
are placed farther apart (or as the rotor is inclined toward the vertical) the detuning effect
of the movement becomes less pronounced.
It
tune and adjust the
is therefore easier to
tickler control simultaneously when the coupling is rather loose, provided that the set is so
constructed that oscillation can be obtained
with a fairly loose coupling without crowding
the filament.
As stated before, the oscillations occur more
readily at low capacity in the aerial than at
Therefore, on rotating
high, as a usual thing.
the condenser to decrease the wavelength, the
It may
set breaks over into self-oscillation.
do this very gradually, beginning with a slight
hiss, or it may do so with a sudden popping
sound in the receivers. The latter state is
difficult to control and causes a great deal of
It is usually due to operatrouble in tuning.
Retion at too high a filament temperature.
duce the filament temperature until the os-
cillations are set
up gradually with change
of
capacity.
Having established these conditions, you
are ready to tune in the broadcasting station.
distant station may be tuned in systemati-
A
by the following method. Increase your
condenser capacity until the removal of your
hand leaves the upper or high wave portion
cally
of the carrier whistle in the receiver.
Then
you pass through the
centre of the wave and beyond to the low-wave
half of the whistle.
Again increase your
capacity until you are set on the upper half of
incline
your rotor
until
Incline the rotor (or separate the
the wave.
the case may be) until you are again
on the lower half of the wave. As you alternate from one side of the wave to the other in
coils as
wave becomes more and more
pronounced and the music or speech at the
You are
centre becomes louder and clearer.
this fashion the
approaching the point of regeneration.
Cave-Man
When this procedure has brought you to such
a point that the next increase in condenser
capacity shows you that the upper portion of
the carrier
wave has disappeared, you
are very
The last few
close to a perfect adjustment.
are
of
the
condenser
best
made with
settings
condenser of about three plates.
A condenser with capacity of .001 with a
vernier plate can be used instead.
If the station is about 50 to 100 miles away,
tuning should
be easy. At 500
a
vernier
miles a
is
little
in
It
Works
adjustment of the rheostat or vernier conis occasionally required.
It is my experience that anywhere from 10 to 30 minutes
is required to make a
satisfactory adjustment
of the controls to tune to a station at a distance
of 1,000 miles.
1
confidently believe that any listener with
a single-tube set, unless in unfavorable territory, can hear stations at that distance,
hough of course manufacturers will not guar-
antee any such
This is
ranges.
largely because
to
old
man
the
has
a
stronger stations
and considerable
Static
habit
running
a
of
file
across your lead-
patience in tuning in the faint
in wire,
pouring
down your
aerial, dumping
shot
stations.
At
329
denser
care
required
tune
But
Stuff,
1,000 miles
gravel into your
with a single
condenser and
you must
emptying wagon
loads of hard
tube
make
accurate
allowance for the
coal
THE PRIMITIVE BUT EFFECTIVE VARIOCOUPLER
capacity effect of
into
your
battery.
Shown at the left, consists of two coils wound on cardboard rings, and
But don't be
your body; you
slides on a section of broomstick.
Sixteen-months-old Doris Marie
must avoid any
afraid. Buy your
Tannehill is listening intently to whatever this extraordinary set of her
father's is bringing in
jar of your equipparts, tie them
ment; you must
together, part
not change your position in front of the reyour hair in the middle and go after Havana and
San Francisco and Schenectady. You can bear
ceiver; and you must have patience.
In other words, at distances in excess of
as far but not as loud with a single tube as you
can witb two stages of audio-frequency amplifi1,000 miles you must "sit in the middle of the
keep your hair parted in the middle,
keep your stogie on the same side of your face,
etc. (though
never could say that there was
decided
effect
from the hands of my watch
any
"
In this way I have listened
moving around !)
with great enjoyment to a concert at a distance
of 1,100 miles for more than an hour without
remember about a
any but slight cramps.
year ago watching a man tune in a Detroit
station at a distance of more than 1,000 miles
boat,
I
I
while
a
friend
(not
myself!)
sat
carelessly
with his feet on the work bench beside the receiver.
Just as he succeeded in tuning in
with complete satisfaction and told us to
listen, his friend took his feet off the table.
We could hear nothing.
Of course, with stations at that distance, the
receiver does not remain in perfect adjustment.
Because of slight changes in capacity of the
aerial, due to swinging or other causes and
perhaps to changes in filament current, a slight
cation.
I bave consistently obtained greater
ranges witb one tube than witb three.
The main idea is to get something that will
bring in the signals. Afterwards you can worry
about selectivity, radio-frequency amplification
and
shielding.
P. S.
The same day the above was written
went home, spent about an hour weeding out
the various stations, using one tube, and finally
I
WGY
at' Schenectady perfectly at a
picked up
distance of about 1,450 miles.
On turning on
two stages of audio-frequency amplification
this station was as strong as one could listen
to comfortably with a headset on.
Tuning-
used were as described above two homecoils on a piece of broom pole.
And
please note that the above results are only
coils
made
There are many men here
ordinary.
claim to have heard Kansas City stations
crystal.
who
on a
A
Super-Sensitive Long-Range
Receiver
Another Invention of Edwin H. Armstrong Which
By PAUL
A
^STRONG,
fame,
called
radio
of
it
He named one
a
"Rolls-Royce."
after the "flivver,"
It was his single-tube supernotBut,
regenerative receiver.
to
be
which
are
the
marvels
withstanding
unearthed from beneath the intricacies of the
too.
super-regenerative scheme, the real
radio reception meth-
ods
Calls the "Rolls-Royce" Receiver
GODLEY
F.
receiver
He
may not yet have learned it, that the threeelement vacuum tube as a detector of radio
oscillations has an adjunct which is known as
To be specific, the
its "threshold value."
three-element vacuum tube will not function
"bug" on
a detector until the incoming oscillatory
currents are of a certain disappointingly large
As a result of this defect (we are
value.
as
sorely
super- super-
it
sensitive radio reception methods
has a
keen and long
hankering
to know all about that
most sensitive receiver,
unsatisfied
the super-heterodyne.
That long-to-be-remembered sporting
surging signal currents
to dwell in our
The Super-Heterodyne
Here, again,
very
of
we
come
find the practical genius
of regenera-
Edwin H. Armstrong, inventor
and super-regeneration, applied to a receiver designed to help America terminate the
World War. Again we find a war development
tion
For
of great peace-time value.
Armstrong and the author of
been close friends.
many
years
this article
have
proposition so spectacular and successful
not surprising, therefore, that Godley knew of the super-heterodyne
receiver and used it in his tests at Ardrossan,
outcome, the
bridging of the Atlan-
Scotland, in December, 1921, when he proved
its value by copying signals from about thirty
in
tic
its
last
American
winter by
amateurs,
brought the
It is
amateur stations located
this country.
THE
in
various sections of
EDITOR.
super-
heterodyne receiver
into the limelight. Armstrong's phrase, "the
a phrase which he
Rolls-Royce receiver"
coined at the time of his disclosure of the superregenerative receiver, added considerable prestige to that intriguing and mystifying word,
"
"
super-heterodyne.
And, when, in starting to learn about the
super-heterodyne, the reader finds the statement that it is a method of radio-frequency
amplification, he is not for one moment to jump
to the conclusion that radio-frequency amplification by the super-heterodyne method is by
any means an ordinary method.
It is
perhaps
the simplest of receivers in operation. At the
same time it is, no doubt, the most complicated
of receivers to construct because of the care
which needs to be taken with it.
Let it be said for the benefit of those few who
tempted to call
many, many
that),
antenna and receiver
circuits, unannounced
and unknown. Long
ago
their
presence
there had
been suspected and, even in
methods
which we would now
early times,
quite crude
were employed in an
attempt to make their
acquaintance. Primamost of these
rily,
attempts had to do
with amplifying the
consider
audible signal currents in the belief that after
the weaker signals had operated the vacuum-
tube detector, they were so nearly exhausted as
to be below audibility. Further study disclosed
the fallacy of this, and then it was that the
great value of employing the three-element
vacuum tube in their amplification prior to
their detection
was discovered.
Radio-frequency amplification has been
used for several years, quite successfully,
at long wavelengths where the frequency of
It was not
oscillations is comparatively low.
until the World War that any great attention
was given to finding out the reasons for the
encountered when radio-frequency
was attempted on very short
Here the oscillatory currents are of
difficulties
amplification
waves.
comparatively
high
frequency.
Up
to
this
A
Super-Sensitive Long- Range Receiver
method of securing
radio-frequency amplification on wavelengths
below about 400 meters had ever been devised.
During the war, both the French and the
British Army and Navy gave considerable
attention to this phase of the art, for the reason
that communication between airplanes, destroyers, and division headquarters had to be
carried on through the medium of short-wave
It took but a
radio telegraphy and telephony.
little while to discover that where the higher
frequencies were to be handled in the amplifier,
the distributed capacities inherent to all ampli-
time, no readily practical
fier coils, circuit
cles,
wiring,
and the elements
it is
vacuum tubes
Yet, as a loyal American, and an
link
in the communications system
important
of our expeditionary forces, it behooved him
to provide, with such American made equipment as was at hand, a means of performing this
so urgently needed service.
Perhaps his mental processes at that time were something like
this.
"
Radio-frequency amplification on long
wavelengths is a practicable proposition.
Radio-frequency amplification on very short
wavelengths is not a practicable proposition
with vacuum tubes and other material avail-
The
capacity
the
elements of the tubes, terminals, and the layers
of the windings upon the radio-frequency
transformers, were sufficiently large to induce
the currents to pass through them rather than
through the paths laid out for them. Under
these circumstances only a very small percentage of the currents actually passed through
the transformers or the vacuum tubes to
perform their functions there. Result, no
amplification, although the amplifier tubes and
their connected circuits either singly or in
fixtures,
Why not, then, by virtue of a frequency
changer, change the wavelength from short to long
prior to amplification; amplify it as a long-wave
and detect it afterwards?" Aposcillation
that
seemed reasonable enough and I
parently
able.
it took him more than a few moments, not only to conceive the idea, but to lay
his hands upon the medium which would enable him to make of the conception a practi-
doubt that
At any rate, as nearly as available
records show, it was but a very short time after
his introduction to the problem before he
cality.
groups frequently set up oscillations among
themselves, causing a further blocking of the
actually had
10 TUR.N5 3 DIA
40 TURN 5 4l"DIA
TAPPED
and
available.
higher the frequency of the oscillations, the
lower the resistance of the path offered by any
(condenser).
hissing
now
understood that even extremely
capacity
of
very good ones, too
used
by British radio folks.
quite generally
Armstrong, above mentioned, and even then
well known, had none of these British tubes
a class of
vacuum tubes
between adjacent wires, metal
to-do
minimum the capacities existing in the transformers, the connecting wires, and the vacuum
tubes, as a result of which there was developed
small capacities offer a rather low-resistance
The
path to high-frequency oscillations.
given
great
The British were the first to take the most
obvious path, that of reducing to an irreducible
themselves, offered a rather serious barrier to
further progress. The reason for this is evi-
dent when
a
howling.
vacuum-tube receptaof the
or
amplifier
IN
FIG.
to call his
Ci,Ci.Cs.C4= .0007 M.F. MAX.
C5> .00023 M.F.
U-
MIDDLE.
I
The super-heterodyne
what he was pleased
circuit
.1
M.F.
Radio Broadcast
332
It may
super-heterodyne receiver, in action.
be considered in one way unfortunate that
before receivers of this type could be manufactured and put into service on the field, the
armistice had been signed.
But, as though
the super-heterodyne were destined to assist
of history, it quickly found its
hands of a few fortunate, decreated a worlighted, appreciative amateurs
and
was
enthusiasm
packed
away to
shipful
in the
making
into the
way
the dreary shores of Scotland.
Here, during
a short ten days' vigil, it showed its historymaking calibre when it initiated international
amateur radio communication.
As
is being written, considerable tinkerbeing done with super-heterodyne reThe occasion for this tinkering is the
ceivers.
ing
this
is
transatlantic
amateur
tests of
December, 1922.
Before this reaches the reader's hands, there
little doubt but that the super-heterodyne
will have shown again its great dependability
is
and
from great
as a receiver for sorting out, classifying,
recording extremely
weak
signals
distances.
HOW
A
IT
WORKS
THOROUGH
understanding of the operation of the super-heterodyne is no diffiThere are three actions which take
cult task.
place in the receiver in the following order:
J\
a changing of the frequency of the incoming
oscillation; (2) amplification of the oscillation
at its new frequency; and (3) rectification
(commonly considered as detection).
To the novice, the most mystifying function
of the receiver combination is the frequencychanging action. This is simplicity itself.
A detector tube has fed into it the incoming
This same detector has fed
signal oscillations.
(i)
at a frequency of 1,500,000 times per second.
Let us now adjust the local oscillator circuits
so as to produce a frequency of
,400,000 cycles
Under these circumstances the
per second.
two currents differing in frequency by 100,000
cycles per second would re-act one upon the
other in the circuits of the detector, so as to
i
produce the "beat frequency" above mentioned, which would be equal to the difference
of the two initial frequencies.
This frequency-
changing method was devised by Professor
R. A. Fessenden, an American, and is known
as the heterodyne method.
Now, a frequency
of 100,000 cycles per second corresponds to a
wavelength of 3,000 meters. As mentioned
above, there is no great difficulty encountered
when
alternating currents having frequencies
low as 100,000 cycles per second are to be
Three, five, seven or even nine
amplified.
as
of radio-frequency amplification may
be used with complete success if a few necessary precautions are taken.
Subsequent to this
amplification, a rectifier tube (detector) receives
the amplified energy, rectifies it, and, if desired,
passes it on to a second amplifier in order that
the volume of the now audible signals may be
stages
increased.
A
review or the foregoing explanation and
will quickly show that in
reference to Figure
its usual form, the super-heterodyne receiver
is exceedingly easy to tune.
There are only
i
two
prime
One
adjustments.
controls
the
simultaneously oscillations which are
generated at the receiving station by an oscilinto
it
lating
vacuum-tube
circuit.
The
circuits
of
the local vacuum-tube oscillator are so adjusted
as to be either slightly lower or slightly higher
than the incoming signal oscilmixing of the two currents of
different frequency in the detector tube gives
in frequencylations.
The
rise
to
a
new
current
of
entirely
FIG. 2
different
frequency in the output (plate) circuit of the
detector tube which is known as the "beat-
frequency current."
By way of example in
the
let us suppose that the
above,
explaining
detector circuit was tuned to receive signals on
a wavelength of 200 meters. The oscillatory
currents at this wavelength would be recurring
wavelength
the "collector" or antenna
the other controls the wavefrequency of oscillation) of the
of
circuit,
while
length
(or
vacuum-tube
oscillator
circuit.
Having
set
the one at the desired wavelength, it is only
necessary to adjust the other until the dif-
A
Super-Sensitive Long-Range Receiver
333
THE SUPER-HETERODYNE RECEIVER
The
walls of the cabinet are lined with copper sheeting,
ference of their frequencies is equivalent to that
frequency for which the amplifier itself is
The tuning
the circuits in the
output side of the first detector tube and the
input side of the amplifier are set once and for
all and no change need ever be made in them.
suited.
of
and the
will
output
2
it
will
be noticed that the
circuit of the amplifier
also
is
tuned
to the frequency of amplification.
This serves
in great measure to stabilize the action of a
multi-stage amplifier of this type, as indicated
by the fact that when resort is had to this
expedient it becomes immediately possible to
add two more stages of radio-frequency amplification
before
reactions
in
the
amplifier
maximum
efficiency.
The
and
third
final step in
bringing the super-
heterodyne receiver up within striking distance
of the theoretical ideal is to produce in the
circuits of the first detector tube a regenerative
signal
1
between sheets are carefully soldered
be working at or very close to
action
IN FIGURE
joints
upon the
initial
currents).
Not
currents (the incoming
until this has been
attempted do the complications of the circuits
as a whole become apparent to the operator.
But, to those
who
are skilled in the handling of
regenerative circuits and multi-stage
fiers this does not act as a deterrent.
novice even, I should suggest that this
amplithe
To
method
be tried, because a considerable and greatlyto-be-desired building up of the initial feeble
currents results.
have reached the point where any
great pains need to be taken to shield the
circuits
various
stages
of
the
to
amplifier
prevent
CONTINUOUS-WAVE RECEPTION
TREATED
self-oscillation.
ASheterodyne
oscillation of
receiver
Having guarded against selfthe amplifier, no matter by what
advantage may be taken of the
possibilities which lie in the regenerative action
so closely allied with its tendency toward
method,
oscillations.
oscillations in
Prior to the actual setting
any vacuum-tube
up
circuit,
siderable amplification of the signal
which
signals
of
except
advancement
thus
receiver
the
supernot act as a
continuous-wa\e
(undamped)
under certain conditions of
where regeneration of initial
of
con-
may
be present results from the regenerative action
inherent in the tendency toward oscillations.
Control may be had over this tendency by
utilizing a minute capacitive coupling between
the output circuit of the last amplifier tube and
the input circuit of the first amplifier tube.
This usually takes the form of an exceedingly
carefully shielded, variable condenser,
indicated in the figure above mentioned.
Having taken these steps, the amplifier itself
far,
will
small,
as-
FIG. 3
Radio Broadcast
334
2-100 TURN
HONEY- COMB
4
COILS
.0007 U.F
7"
J
FIG.
An
oscillator for
4
continuous-wave reception
frequencies is being effected, and usually then
in an unsatisfactory manner.
A simple and by far the most effective
method
of procuring audible reception of continuous-wave signals is to set up still another
vacuum-tube
oscillator (Fig. 4) in the vicinity oj
the amplifier circuits, this oscillator being so
adjusted as to frequency that a second "beat
the beat-note oscillator carefully,
the oscil-
produced by it even though they be
very feeble ones tend to paralyze the action
of the amplifier.
This problem may be easily
solved by setting the oscillator at double the
wavelength (half the frequency). There allations
ways
exists, .in
the circuits of the oscillator,
the
harmonics of the true oscillation. If
fundamental oscillation (100,500 cycles)
is
so
strong as to paralyze the action of the amplifier, either the third or fifth harmonic will
usually be found of proper strength to give the
desired signal without paralysis of the amplifier
tubes.
The
third
harmonic
obtained by
is
setting the oscillator at double the wavelength
of amplification
(6,000 meters or 500,000
approximately). The fifth harmonic
obtained by setting the oscillator at four
times the frequency of amplification (12,000
meters or 250,000 cycles). Figure 3 shows
this last arrangement.
Attention is called
to the fact that the beat note oscillator need
be no nearer to the amplifier than about four to
cycles,
is
frequency" this time an audible one is
In the case which we considered
produced.
above, where the amplification frequency was
100,000 cycles, the practice would be to set
the second oscillator so as to generate a frequency of 100,500 cycles. The "beat frequency" then produced would be an audible
one, i.e., 500 cycles, which would give a note
having a pitch just slightly lower than that
heard when the middle C is struck on the
due to tube faults are a great deterrent. Tubes
which show inclination toward noisiness should
piano.
Having set this oscillator to produce
the 5OO-cycle tone, it need not be changed,
at
which
regardless of changes
may
made
be
it
only currents- which have a frequency of
100,009 cycles.
In actual practice,
That great thing which is
great importance.
to be desired is silence in the amplifier. Noises
be used in the latter stages of the amplifier
found impractical to
note oscillator at 100.500 cycles,
because, unless' great pains are taken to shield
REGENERATIVE
R.F.A.
I
have found
many
users
multi-stage
In fact,
in the battery circuits.
a poor connection at any point will cause noise,
but it seems that the most common cause
is the existence of carelessly made connections
FIG. 5
circuit
of
complaining about tube noises
which were not tube noises at all. The noises
which I have in mind were due to poor conamplifiers
THESE COILS MAY TAKE
FORM OF STANDARD VARIO COUPLER.-
The super-heterodyne
if
all.
nections
it is
set the beat
LOOP
Care in selecting and placing the tubes
available for use in the super-heterodyne is of
in
the wavelength setting of the receiver.
For, it
will be remembered, the amplifier has passed
to
six feet.
with tuned radio-frequency amplification
A
Super-Sensitive Long-Range Receiver
335
;*,
'"N^V
"""""v
V
PANEL VIEW OF THE SUPER-HETERODYNE RECEIVING SET
There
in
the
is
a separate rheostat provided for controlling the filament voltage of each tube
circuit
filament-lighting
or
to
the
filament-lighting battery itself.
Further, it is frequently necessary to set an
amplifier of this character
so that mechanical shocks
on rubber cushions
due to movements
within the room will not cause a "ringing" of
the tube elements.
Preferably, each tube
should have its own individual shock absorber.
This enables work upon the amplifier while in
operation without great noise in the headphones due to handling units in the circuit.
If
Of submitting an
article to
You
The final touch to be given to the superheterodyne consists in adding to it a stage of
tuned radio-frequency amplification. Of course
complicates tuning. The
strength is fairly well worth
while, however, and the expedient will be
adopted by all true experimenters. This
this
still
further
gain in signal
arrangement is shown in Figure 5.
Having added this improvement, the user
can be certain that he is in possession of the
most sensitive radio receiver ever devised.
are Thinking
RADIO BROADCAST,
trouble by 'considering the following notes as to
you may save yourself and the editors time and
what we want and what we cannot use:
WE WANT:
True accounts of the uses of radio in remote regions.
Short, true stories of adventures in which radio played
occurrences to you or your acquaintances.
an important part: unusual and
interesting
Clear explanations of new or especially effective circuits or uses for apparatus.
Concise and logical discussion of some important problem or phase of radio, whether in the field of
broadcasting, constructing, operating, buying or selling; or of reading or writing that has to do with
radio.
True accounts, of some particular
Humor, when
the object is not
interest, relating
merely
to
"What Radio Has Done For Me."
appear funny, but
to
amusing way. The same applies to drawings.
Clear, unusual photographs are always in order, as are good
present some phase of radio in
an
attractive,
A
liberal rate is
WE CANNOT
with some subject of interest to those interested in radio.
would not have the exclusive rights.
read through several numbers of the magazine to get an idea of the various
way
RADIO BROADCAST
best
diagrams.
USE:
Fiction, unless it deals in a striking
Articles or illustrations to which
The
circuit
paid for material used.
way
to
do
is to
kinds of articles we publish.
How
Far Have You Heard on
One Tube?
64,660
is
the Best Aggregate Mileage Record So Far. Notes on TunThe End of the Contest February 1st
What Others Have Done.
ing.
FEELING THE NATION'S PULSE
By RUSSELL SHEEHY
Mr. Sheehy, who has piled up an aggregate mileage of 63,860 of stations 50 to 2050 miles distant,
has his fingers on the nation's pulse at his home in Newfields, New Hampshire.
He listens-in on
Dallas, Texas; New Orleans, La.; Tampa, Fla.; Denver, Colo.; Wichita, Kansas; Havana, Cuba; Ensenada,
P. R.; Toronto and Montreal, Canada; Lincoln, Nebraska; Chicago, 111.; Kansas
City, Mo., Louisville, Ky.,
and other stations too numerous to mention.
He has reduced the operation of his set to a logical set of rules which should be of value to others in
securing similar results. THE EDITOR.
1
literally
the circuit shown in Figure
i,
I
have been able to hear, from my
home in New Hampshire, most of the
Eastern, Southern, Western and
Southwestern stations on a single
tube.
Most of them come in very clear and
loud when conditions are not extremely bad, and
USING
it is
generally possible for
programme from any one
list
appended.
Many
up one or two
me
to hear the entire
I
my filament on 4.4 volts and very rarely have
to change it.
With most of the detector tubes
I
have tried, the best B battery voltage is
Of
on the
course, this has to be found by experimenting with your particular tube. I have
capable of pick-
found that two potentiometers are quite an
of the stations
sets are
trol. A filament volt-meter or ammeter is a good
addition, and after once finding the plate and
filament voltages, this part of the tuning is
almost eliminated from the routine. ' operate
1
8.
when long
from these stations,
but somehow or other they cannot be held.
With the circuit am employing, after once a
distance signals are desired.
connection, the variable condenser
across the phones and batteries is also very help-
station has been found, it may generally be held
until you desire to tune in another.
the slider grounded
may cause
the tube to oscillate, by moving it toward the
negative side, and it is just before this point of
oscillation that signals are clearest and loudest.
ing
selections
I
My
entire outfit is home-made, including the
variocoupler which is wound with 35 turns on
the stator and 35 on the rotor. No switch
points or taps are used. After experimenting
with different values,
suited
my
aerial,
found these values
the series condenser being
I
.001 mfds. in the aerial circuit.
The only
had with this circuit was
condensers
and I strongly advise
paper
the use of mica condensers and tubular leaks in
the grid circuit. The .001 mfd. variable condenser across the phones and batteries
may be
trouble
I
in the
substituted by a .002 mfd. fixed condenser or
sometimes on near-by stations by a .005 mfd.
fixed condenser.
In the last instance, the signal strength is very materially increased.
The entire circuit is quite simple of operation
and most of the tuning is done with the condenser in the aerial circuit and the tickler con-
asset
In
ful.
this
The potentiometer with
at the correct position of the tickler
The
set
that
moving the condenser
is
operating at
no oscillation, but there
each side of your signal.
its
is
best
when you find
way produces
either
a sort of "purr" on
The simplest method for beginning the
operation of this set is to set your tickler at
about 10 and move the condenser until a signal
is heard (this is taking it for granted that you
are on the correct switch point for the broadcasting wavelengths if you are using a varioIf you find
coupler with a tapped primary.)
a squeal on either side of your signal, loosen the
tickler, that is, bring it back toward zero, moving it very slowly, however, and the distance
you will have to move it depends on the
strength of the signal.
If it is
quite loud,
move
Feeling the Nation's Pulse
With the two potentiometers across the A
three or four degrees, whereas if it is weak, a
fraction of one degree may sometimes suffice.
it
Every time you move the
tickler
it is
battery, it is a good plan to put a switch on one
side of the line from set to battery and then
necessary
to readjust the condenser in the antenna circuit, going back and forth until the signal is
there
produced without any interfering noises. If
no signal is heard when the condenser is moved,
it
generally necessary to tighten the tickler
coupling, moving it up to 15 or 20 and reducing
it according to the previous routine after a
signal has been picked up.
This outline of operation may seem rather
long-winded, but it
takes much longer to
it
about
tell
than
it
become accustomed
it
to
you know
about where to
your
just
set
set the tickler at
start so that
it
the
is
generally necessary only
to move the condenser
in order to receive the
Don't put up a length of telephone wire when
you can get some aerial wire for a dollar or less.
Keep your aerial well insulated on both ends
and don't spend one month on a set and one
hour on an aerial and ground system. They
have tasks to perform which are as important
and then no
when you
move
the condenser,
you will have to try
different values of fila-
ist
heard with the mileage opposite each.
If a
diagram of the receiver you are using has
already appeared in RADIO BROADCAST, it is
not necessary to do more than refer to the
page of the issue in which it appeared.
First consideration will be given to descrip-
accompanied by photographs, and the
cost of building the receiver will also figure
judging a report.
The final reports in the "How Far Have
You Heard?" contest will appear in RADIO
BROADCAST
than February
ist
EDITOR.
ment current and B
It took me two days to find
battery voltage.
the proper places for these two variables with
my last
tube, but this particular point
worth the time spent in securing it, for
is
it
well
stays
If these instructions
are carefully followed,
may
you
that
rest assured
you are
if
get-
ting poor signals some
night there is no need
of going over to your
neighbor's, as he will
be
in
My
the
same boat.
ground system
rather unique, and I
have found it better
is
than those ordinarily
employed. It is a single wire directly under
the single-wire aerial
(125 ft. long), buried
THE
about a foot in the
earth, at the end of
which are extended six
wires about 50 feet in
a fan shape also buried about a foot and exaerial runs
tending beyond the aerial.
Material received
cannot be considered.
for April.
it-
self.
your aggregate mileage exceeds
do not include a description of your
receiver, merely send in a circuit diagram
accompanied by a list of the stations you have
in
left
as those of the set
Unless
tion just on the point
of oscillation and there
a click
1
50,000,
tions
signal
off a little at a time.
THE CONTEST ENDS FEBRUARY
desired signals. If you
find that you get a sta-
is
is no drain such as would otherwise exist.
Don't turn your filament right off. Turn
is
does actually to carry
it out, and once you
337
later
My
east
and west with the
ern end.
I
lead-in
couldn't find
on the west-
much advantage
in
leaks,
direction, but think that the direction from
which you are to receive should be reasona-
nothing to pull the set apart for when
the signals are not coming in particularly well
on some night. After testing the A and B
bly free of objects that are near, like trees
Try to have a clear view in the
direction of the transmitting stations consid-
and finding them all right you had
better leave the set alone and call it a "bum"
ering yourself as standing
night and wait until the next night when you
be surprised at the way it works. Give it
a fair chance. When your automobile goes bad
you don't immediately take the engine apart,
take the gas tank off, or see what the carbure-
Don't run No. 24 wire to your
use No. 14 at least.
there very well afterward.
With mica condensers and tubular grid
there
is
batteries
will
made
Of course not. Give the radio
Look at some simple things
receiver a chance.
like loose connections or low batteries first
tor
is
of.
before you take condensers apart.
and houses.
on the top
of the
aerial.
This
set
really selective
battery,
and sharp,
especi-
have built an 8-inch cage lead-in. It
sometimes possible to leave the antenna con-
ally since
is
is
A
I
denser set and tune in three or four different
stations by properly manipulating the tickler.
The following is the list of stations heard that
are 150 or more miles distant:
Radio Broadcast
338
MILES DISTANT
STATION
WFAA
WRR
WCAR
WEAY
WBAY
WAAB
WGAQ
WEAT
WHAD
WHA
Texas
Dallas, Texas
San Antonio, Texas
Houston, Texas
Fort Worth, Texas
Dallas,
-
.
.
.
.
.
.
.
Orleans, La.
Shreveport, La.
Tampa,
Fla.
.
.
.
.
PWX
Havana, Cuba
WGAD
Ensenada, P. R.
Toronto, Canada
Toronto, Canada
Montreal, Canada.
Montreal, Canada.
WGM
BFGA
CFCA
CKAC
CFCF
WGAT
WGAS
WDAP
KYW
WMAQ
WWJ
WCX
WHB
.
.
.
.
500
1300
960
1835
1470
IOOO
IOOO
.
.
.
IOOO
.
.
1600
.
1700
.
450
450
225
225
.
.
Lincoln,
.
.
Nebraska
Chicago,
Chicago,
Chicago,
Chicago,
1400
Illinois
.
.
Illinois
.
.
Illinois
.
.
Illinois
.
.
.
.
.
.
Detroit, Mich.
Detroit, Mich.
Kansas City, Mo.
Cleveland, Ohio
.
.
Cleveland, Ohio
.
.
Dayton, Ohio
.
.
.
.
.
.
Mo.
.
Ohio
Cleveland, Ohio
Cincinatti,
900
900
900
900
650
650
FIG.
1
2
3
4
5
6
7
8
9
Orangeburg, S. C.
Charlotte, N. C.
Minneapolis, Minn.
Minneapolis, Minn.
840
840
600
600
750
800
600
900
800
.
.
.
I
Variable condenser of .001 mfd. capacity.
Any variocoupler of standard make, range 150 to 600
meters.
i
-megohm
grid leak.
Grid condenser of .0005 mfd. capacity.
Variable condenser of .001 mfd. capacity.
2oo-ohm potentiometer.
2OO-ohm potentiometer.
B battery, 165 to 22 volts, for UV2oo tube.
Antenna 125 feet long, 40 feet high, 7/22 stranded.
10
1300
I IOO
WJAX
WLB
WAAL
1450
.
.
Indianapolis, Ind.
Indianapolis, Ind.
WAAD
WGAM
WBT
.
.
WLK
WOH
WLW
.
.
St. Louis,
WHK
1700
1650
.
KSD
WFO
1650
1860
.
1
.
WSB
WAAP
WDAJ
.
.
Milwaukee, Wisconsin
Madison, Wisconsin
Denver, Colorado
Wichita, Kansas
College Park, Ga.
.
Atlanta, Ga.
Atlanta, Ga.
KDZU
.
.
.
New
1650
Counterpoise ground. Single wire 125
one foot deep, under the antenna
WBAU
WOC
WOI
WGF
WHAS
WBAZ
WSN
NOF
1
150
WMU
1
150
KPM
Hamilton, Ohio
Davenport, Iowa
Ames, Iowa
Des Moines, Iowa
'.
.
.
.
A WELL-DESIGNED 3-CIRCUIT TUNER
Of the type that has been
build their
own
will
in service for several years.
do well to attempt the same
class of
850
1050
1200
I2OO
Ky.
Richmond, Va.
Norfolk, Va.
Washington, D. C.
Washington, D. C.
Washington, D. C.
Louisville,
.
feet long, buried
Those who
workmanship
8/0
550
550
450
450
450
The "Carpet
WHAV
WGL
Wilmington, Del
Philadelphia, Pa
WIP
Philadelphia,
WOO
2CDT
3'5
3' 5
Philadelphia, Pa
Philadelphia, Pa.
3'
WIAN
Allentown, Pa
WGAL
Lancaster, Pa
WJT
KQV
KDKA
Erie,
WOR
WAAM
WRP
2XJ
WEAM
WIAD
WBAN
WAAT
WCAN
W1AO
WGY
WGR
WRL
WHAM
WFAG
WRW
WMAK
WCAB
KDOW
WCAX
WHAZ
5
Pa
\Vilkes Barre,
2XAi
31
Philadelphia, Pa
WCAU
3XW
WEAK
WBAX
WJAS
WJZ
35
5
3 '5
.
280
Parkersburg, Pa
Harrisburg, Pa
375
Pa
250
275
35
Pa
480
Pittsburgh, Pa
Pittsburgh, Pa
500
Pittsburgh, Pa
Newark, N. J
Newark, N. J
Newark, N. J
Newark, N. J
Camden, N. J
Deal Beach, N. J
N. Plainfield, N. J
Ocean City, N. J
Paterson, N. J
Jersey City, N. J
500
240
240
240
240
3'5
250
225
225
225
225
500
mo
Jacksonville, Fla
Milwaukee, Wisconsin
Schenectady, N. Y
Buffalo, N. Y
Schenectady, N. Y
Rochester, N. Y.
Waterford, N. Y
Tarrytown, N. Y
Lockport, N.
Newburg, N.
S. S.
885
150
400
150
35<>
.
Y
Y
385
200
America, at sea
foreign countries by employing various sized
coils according to the wavelength desired.
"One
most remarkable features about
that it is quite simple to tune out
stations that are not wanted, and another very
attractive feature is that the materials necessary may be had for a few dollars.
Mr. McMiller says that he has discarded two
variometers and a variocoupler and a two-stage
audio-frequency amplifier in favor of the very
this set
of the
is
small outfit he has described.
In using the same circuit, Mr.
"
Young
says:
started on a
'Carpet of Bagdad' and
will give a descripjourney one evening, and
tion so that you may judge the value of the
stops were all over 500 miles from
design.
my starting point, the farthest being 40 miles
had not been long on my way
by air line.
when the "Voice of the South" from The
Atlanta Journal stopped me with the well-
My
I
I
My
i ,
1
I
known melodies of
the Southland. Continuing,
soon heard a voice saying, 'This is WFAA,
the Dallas News, and then I heard 'In the
Garden of My Heart' being sung by Mr.
I
Losier.
Only a short distance from there
I
150
63,860
CARPET OF BAGDAD
simple application of the single-
circuit regenerative
ANOTHER
Fig. 2 on page 340.
tion by Mr. W.
receiver is found in
was brought to our attenMcMiller of the Southern
It
Methodist University, Dallas, Texas. In describing the operation of this circuit, which Mr.
W. M. K. Young of Kansas City, Mo. calls the
modern "Carpet of Bagdad," Mr. McMiller
says: "During the summer months when so
fans were complaining of the so-called
static, I was receiving Kansas City, St. Louis,
Jefferson City, Denver, Cincinnati, Atlanta,
Houston, San Antonio and other stations a long
many
distance off quite regularly.
the very least of my troubles.
weather has
up
set in,
to 1400 miles.
I
I
Static has been
Since the cooler
have been able to receive
have been able to hear 128
different stations in 27 states as well as Cuba
and Mexico. It is also possible for me to hear
I
heard WBAP, the Fort Worth Star Telegram.
These old songs from the Southland were
beautiful and I hated to leave them, but adhad to continue.
venture was in the air and
150
Y
Aggregate mileage:
THE
339
750
Burlington, Vt
Troy, N.
180
180
of Bagdad'
A SUITABLE VARIOCOUPLER
For broadcasting or amateur reception, with its
metal shield which reduces body capacity effects
Radio Broadcast
340
With a standard loose-coupler, Mr. Edwin
H. Sands, State Housing Commissioner at Des
Moines, Iowa, has been able to pile up an aggregate mileage of 25,835, this with a nonv
regenerative receiver.
The Aeriola Seniors are standing up very
Mr. W.
well.
J.
Buckley of Fairfax, Oklahoma
has an aggregate mileage of 19,030.
VAR.COND
RHE05TO
MR. MCMILLER
S
PANEL ARRANGEMENT
Controlling the B battery from
the panel is a great convenience
So back to the North went to get a serenade
from WLAG, Minneapolis, as passed over on
the way to KDKA at Pittsburgh and then on to
WRL, Union College at Schenectady, N.Y.
This completed the Eastern part of my trip, and
started back, stopping at Indianapolis with
the Hatfield Electric Company and hearing
WWJ, the Detroit News, while waited. My
next and last stop was back in the Central
West, where the mountains hold a station
designated as DN4 operated by the Colorado
National Guard at Denver, a beauty spot 640
miles from my home.
"
My first evening's journey is completed and
have lengthonly a memory now, but while
ened my trips and have spent more time at each
I
1
I
single
jump
my stops, my first evening will always be the
best that I ever took because of the thrill and
of
enjoyment
it
The best report from Aeriola Senior operators
we have received so far comes from Mr. A. R.
Ackerman, who has received directly from Los
Angeles at his home in Nashville, Tennessee.
This
1800 miles.
is
Mr.
W.
L.
regenerative receiver
seems to be leading in the contest, and the
great number of letters we have received and
the great distances being covered have made
THE
single-circuit
Carlisle, of Lisbon,
North Dakota
has come so close to the aggregate mileage
necessary that we just can't overlook him.
His aggregate is 14,795.
STANDARD REGENERATORS
from users
tive receivers
REPORTS
of standard regenera-
John R.
Corrish of Bridge St., Monson, Mass, aggregates 18,465 miles with 1,500 miles as his best
are fairly good.
jump.
Mr. C. L. Hobart of Grant's Pass, Oregon reports an aggregate of 45,580, his best single
single
jump being
1,275 miles.
VARIOMETER REGENERATORS
gave me."
THE STANDINGS OF CONTESTANTS PREVIOUSLY
UNMENTIONED
His best
1,425 miles.
Mr. A. B. Johnson, Garfield Ave., DuBois,
Pa. has an aggregate mileage of 17,375 with the
best single jump of just 1000 miles.
I
I
is
best report from the users of a varioregenerator receiver is from Maury
meter
THE
Simmons, 2700 Darien St., Shreveport, La.,
whose aggregate is 36,250 with 300 miles as his
best single jump.
1
necessary for us to increase the minimum
of aggregate miles to 15,000.
Mr. Leonard B. Robinson, 537 Hillside Ave.,
Glen Ellyn, Illinois has an aggregate mileage of
it
number
30,430.
Mr. R. A. Riggs of Vevay, Indiana has an
aggregate of 22,045 miles.
Mr. George J. Schottlerof Dexter, Minnesota
aggregates 16,790 miles.
We rather expected to find that the users of
the Rheinhartz circuit would stand well to the
front in this contest, but the best single distance
made by any contestant using that circuit is
1,325 miles, and there is no aggregate mileage as
high as 15,000.
FIG. 2
The "Carpet
justed,
all
of
Bagdad"
tuning
is
circuit.
When
the set
is
ad-
done with the variable condenser
Tube
55,000 Miles on a Dry-Cell
ANOTHER BEGINNER'S STORY
By HARDING GOW
SPENT last summer on
Orcas Island of the San Juan
group up in the northwest
corner of the United States.
Of course we took a crystal
set along, but as that limited us to one station
it
naturally followed that we had to have a
did not know the
tube set. At that time
difference between a
variometer and a grid
WE
I
leak, so
to the
came down
1
On
Seattle Radio
Show
in search of information and material.
selected a tube
which had just been
put on the market and
which required only
one dry cell for the A
battery, inasmuch as
there was no way of
I
is
The hook-up is the ordinary three-circuit
regenerative type except that I used a variable
condenser across the B battery and phones, and
tickler
American organization to maintain our position in radio communication.
The Radio
Corporation of America is the result. Commander Hooper has entire charge of the Navy's
intricate radio communication system and is
head of the Radio Division of the Bureau of
Steam Engineering. He has some very constructive views on standardizing equipment
and is preparing for RADIO BROADCAST an
article on this important subject, which will
appear in the March number. THE EDITOR.
I
I
I
1
I
I
across the
and find
another
Commander Stanford C. Hooper, U.S.N.,
the man who suggested the formation of an
I
results.
1
Standardizing Radio Equipment
charging storage batteries at East Sound,
and decided on spiderweb coils because
had obtained good results with them on a
crystal set, and also because there seemed to be
practically no data obtainable on them and I
was curious to try out their possibilities.
may
add that
have never regretted the choice.
In first assembling my apparatus,
followed
the conventional custom of compactness and
tried
got the condensers too close together.
shields between them and also a panel shield
for body capacity but this seemed to me to
reduce materially the signal strength, and in
working distant stations on one tube, the tiny
bit of energy absorbed by the shields may decide whether the voice of that fellow 1,800
miles away comes in clearly or as a confused
murmur. So pulled the set to pieces (a frequent occupation at first) and spaced the condensers well apart in a larger cabinet, mounting
the coils on the ends of four-inch brass rods to
Then
get them away from the condensers.
began to get
final assembly is shown in the photoam free to admit could not be
which
graph,
called handsome, but the way it reached out
and gathered in the distant stations was a constant surprise and delight.
The
them
coil,
of great value in
tuning the plate circuit without changing
the
tickler
coupling,
and they also bring out
the tone of both voice
and music.
The secondary condenser
is
sensitive to
body
capacity, but
with the type of vernier handle
shown
it is
possible to avoid an-
noyance from
this
cause.
For the values given,
the primary and secondary condensers work
best on about the same reading.
I
usually set
them at 35 to 40 and pick up the stations by
varying the primary coupling, maximum signals
being obtained by adjustment of the plate condensers and the primary vernier.
The set is extremely selective. I think the
most surprising feature to my wife was that she
could shift from Fort Worth, Texas, to Calgary,
Alberta, by moving the primary coil perhaps an
inch!
From
ten stations could be tuned in and
resetting the condensers, and I frequently was able to pick up both
ends of test conversations between stations.
six to
out in this
way without
One
night I heard Calgary, CFCN, calling
I
listened to them
Wallace, Idaho, KFCC.
for some time when KFAY at Medford, Ore.,
came in, KDZZ at Everett, KMO at Tacoma,
and yXI at Portland, all by shifting the priseemed to hear them better
mary coil, and
I
342
Radio Broadcast
than they heard each other as several of them
Concerning Mrs. Male's Lecture on Cancer
KFAP
KDYS
KFBB
yXD
Mont
Butte,
525
Grest Falls, Mont.
Havre, Mont.
560
625
325
.....
Polytechnic, Mont.
KDZK
Reno,
Reno,
KFAS
CJCG
.
Nev
Nev
KFBM
Winnipeg, Man
Astoria, Ore
7YJ
Corvallis,
660
660
1175
190
Ore
Eugene, Ore
Medford, (Listed Central Point)
Portland, Ore
Portland, Ore
Portland, Ore
Portland, Ore
Portland, Ore
Portland, Ore
Portland, Ore
Houston, Tex
KDZJ
KFAY
KYG
290
325
450
'
KGW
KGG
KFAB
7X1
KQY
7X8
WEAY
WFAA
WBAP
Tex
Fort Worth, Tex
Salt Lake, Utah
Salt Lake, Utah
Vancouver Barracks, Wash.
....
KDYL
BQ3
KZV
.
Wenatchee, Wash
Wenatchee, Wash.
Walla Walla, Wash, (new Sta.)
Yakima, Wash
KDZI
KFBF
KFV
225
225
225
225
225
225
225
THIS
IS
THE CIRCUIT USED BY MR. COW
On one
tube, he has heard stations 2000 miles from his home
2OOO
I8OO
Dallas,
KZN
1780
780
780
22 5
150
I5P
-285
'75
55.150
"W" stations and almost all of the remainder have been heard by my wife, as we use
two headsets, the only distant station on
which
have not her check being KYW.
It. was hard to leave out WEAR, Baltimore,
2,450 miles, of which had the call clearly, but
kellingham started up on so nearly the same
of the
I
I
wavelength that
name.
The summer
stations listed have
identified both
by
been positively
and name, and all
all
call letters
I
was unable to
static
was bad
verify the
until well into
were listed
from Sept. loth to November i3th when we left
East Sound.
September, so
The
343
most
of the stations
Concerning Mrs. Male's Lecture
on Cancer
OUR
October issue we called attention to the broadcasting of a lecture by Mrs. Annie Riley Hale on
the subject of cancer treatment.
Mrs. Hale feels that some of the statements in that article are a personal reflection upon her. Our
purpose was not to attack the character, the motives, or the education of Mrs. Hale in any way, and we wish
to retract anything that could be so construed, and to express our sincere regret for it.
The object of the
article was to remind the broadcaster of the duty he owes to the radio public to scrutinize with care anything
he sends out which is calculated to affect people's decision and judgment, and especially so in matters affectare not to be understood as modifying views which we expressed, but
ing health and perhaps life itself.
IN
We
we
are very sorry to have said anything that could be considered as a personal criticism of Mrs. Hale.
EDITOR.
THE
Notes on the "Parker" Circuit
By ZEH BOUCK
Since the publication in the December issue of RADIO BROADCAST of the circuit used by Mr. Parker in
remarkable reception, letters have been received from enthusiasts who, having achieved similar results,
Due to the unconventiondesire to improve their apparatus still further by the addition of amplifiers.
Amplification,
ality of the circuit, this presents something of a problem to our less experienced readers.
and other interesting possibilities of the circuit are covered in the accompanying article. THE EDITOR.
his
REFER
to the Parker circuit in order to
designate the hook-up by a name already
known to the readers of RADIO BROADCAST.*
Mr. Parker, however, was not the first to
see the advantages of the hook-up, for receivers similar to his have been used by
1
amateurs for some years, and no little original
work on Mr. Parker's particular phase of the
circuit was done by Mr. Walter J. Howell, at
present Assistant Radio Inspector of the
Second District, who initiated the writer into
the possibilities of the receiver.
The diagram as previously given
is
not well
A
If
the
additional
am-
added on
B battery,
them may be required than in other
plifying high-voltage batteries are
the positive side of the detector
more
of
This
circuit
was described
in
the
December number,
pp.
114-117.
FIG.
sets,
if
the
operated on considerably
tube is
than the full
This is because,
detector
less
voltage of the first block.
in Mr. Parker's original circuit, any reduction
of the detector plate voltage necessarily lowers
that of the amplifier. On the other hand, if
the additional batteries are placed on the negative side of the original block, the potential
on the detector will be increased sufficiently to
render the bulb inoperative; or, if the connection
first
adapted to audio-frequency amplification, using
and B batteries for the detector
common
and amplifier tubes.
regenerative
the
is
made
to the
minus terminal of the
block, rather than to the tap, a portion of
high-voltage batteries will be short-cir-
These difficulties are obviated in Fig.
which shows the circuit adapted to a two-
cuited.
i
,
It will be noted that the destage amplifier.
tector plate voltage is varied by tapping to a
positive potential with the lower end of the
variocoupler secondary, rather than by varying
the connection between the B battery cells
and the ground lead!
I
of the "Parker" circuit, described in RADIO BROADCAST for December, used with a two-stage
Instead of varying the connection between the B battery cells and the ground lead, the detector
amplifier.
plate voltage is varied by tapping to a positive potential with the lower end of the variocoupler secondary
Diagram
RADIO BROADCAST ADVERTISER
This Panel Will Improve Your Set
CONDENSITE
best panel made is none too good for your set.
Dependable
insulation is vital because it has a direct bearing upon the clear-
THE
and
ness
sensitivity of both transmission
and reception.
Every thinking radio enthusiast certainly wants the highest type panel
he can obtain and the surest way to get it is to insist upon Condensite
Celoron.
This strong, handsome, jet-black material
material
it is
a radio insulation
That
frequencies.
is
why
higher dielectric strength
it
made
will
than you
not merely an insulating
is
meet high voltages at radio
give you greater resistivity and a
will
to
ever need.
Make your next panel of Condensite Celoron. It. machines readily,
engraves with clean cut characters and takes a beautiful polish or a
rich dull
mat
surface.
An Opportunity
for
Radio Dealers
Condensite Celoron Radio Panels and Parts offer a clean cut opportunity to the dealer
who is keen on building business on a quality basis. Write us to-day. Let us send you
the facts.
You'll be interested.
Diamond
State Fibre
Company
Bridgeport (near Philadelphia), Pa.
Branch Factory and Warehouse, Chicago.
Office* in principal cities
In
Canada: Diamond State Fibre Co.,
Ltd., Toronto.
Radio Broadcast
346
A
cuit,
variation in the fundamental cirwhich has proved remarkably popular
slight
where introduced,
is
shown
in
Fig.
2.
The
tuning elements, exclusive of the variable condenser, are three home-made variometers,
which may be constructed for less than fifty
The variometers are wound on
cents apiece.
cardboard statofs and rotors (the stationary
and revolving parts) three and a half and three
The stators
inches in diameter respectively.
wound with 18 turns of No. 22 or No. 24
are
and the rotors with
The variometers may
22 turns of the same.
be panel mounted by bushings as described in
the Grid in Radio Broadcast for December. The
connection between the stator and rotor of variometer number two is broken in order to permit
the hooking-in of the detector "B" battery.
C2 is a .0015 mfd. telephone shunt condenser.
The set is slightly more difficult to tune than
Mr. Parker's circuit, but the semi-regenerative
function of the third variometer is soon comprehended with surprising results. Variometer number one, in conjunction with the
variable condenser (which should be provided
with a shorting device for waves in the neighborhood of six hundred meters) varies the
single cotton-covered wire,
FIG. 2
Several other minor changes have been made.
variable condenser has been shifted to the
The
antenna side of the coupler primary, by which
maneuver, control of the set is apparently
facilitated, owing to a possible stabilizing effect
of the ground on the directly coupled grid.
A grid leak, quite an important item, has been
added, and a condenser placed across the
phones or primary of the first transformer,
For convenience, the
as the case may be.
receivers have been shifted nearer to the plate.
If, when constructing the set, the experimenter
does not fancy the immediate expense of amplifiers, the auxiliary apparatus is merely eliminated on the diagram, along with the extra
B batteries, and the phones connected in place
of the first jack.
SUPPLEMENTAL
LIST OF
wavelength. The middle variometer controls
feedback or regeneration.
The set has no taps, all tuning elements being
continuously variable by the variometers and
condenser. As a result, it is remarkably selective, with tuning possibilities that, used appreciatively, rival the best inductively coupled
outfits.
BROADCASTING STATIONS IN THE UNITED STATES FROM NOVEMBER
TO DECEMBER 24 INCLUSIVE
CALL
SIGNAL
OPERATED AND CONTROLLED BY
KFCL
KFCQ
KFDB
KFDC
KFDF
Radio Supply Co
Wyoming Radio Corp
Casper,
KFDH
University of Arizona
Tucson, Arizona
KFDJ
Oregon Agricultural College
Knight-Campbell Music Co
Guy Greason
Radio Equipment Co
Corvallis,
Los Angeles Union Stock Yards
Mercantile Trust
KFEJ
KFEP
KFGG
KFGH
KFHJ
WLAG
Los Angeles, Calif.
Casper, Wyoming
San Francisco, Calif.
Motor Service Station
KFDL
KGW
23
.
Company
of California
Astoria Bridget
Leland Stanford Jr. Univ
Fallen Company
Portland Oregonian
Cutting
&
Washington Radio Corporation
Spokane, Wash.
Wyoming
Oregon
Denver, Colorado
Tacoma, Washington
Denver, Colorado
.
Astoria,
Oregon
Stanford University, Calif.
Santa Barbara, Calif.
Portland, Oregon
Minneapolis, Minn.
RADIO BROADCAST ADVERTISER
Receiving
set
is
complete
withou
Gfieflcprodueer Supreme
R-2 Magnavox Radio with
18-inch horn: this instrument is intended for those
who wish the utmost in
amplifying power; for large
audiences,
etc.
dance
.....
halls,
$85.00
R-3 Magnavox Radio with 14inch horn the ideal instrument for use in homes, offices, amateur stations,
etc
$45.00
:
.....
Model
C Magnavox Power
Amplifier insures getting
the largest possible power
input for your Magnavox
Radio. 2 Stage
$80.00
110.00
3 Stage
.
.
When you purchase a Magnavox product you possess an
instrument of the highest
quality and service.
T7 VERY improvement in the science
** of radio
broadcasting and reception only emphasizes the truly
extraordinary qualities of Magnavox.
To
enjoy all that radio offers in the
of
way daily concert, lecture and news,
ask your dealer for a receiving set
equipped with the Magnavox Radio
Reproducer and 2 -stage Power Amplifier.
Magnavox can be used with any
good receiving
the
set
the better the
more Magnavox can do
set,
for you.
products can be
had of good
where.
of
new
dealers every-
Write us for copy
illustrated
booklet.
The MagnavOX Co*, Oakland, California
New York: 370 Seventh Avenue
Radio Broadcast
348
WOAH
WOAK
WOAL
WOAN
WOAP
WOAQ
WOAR
Palmetto Radio Corp
Collins
WOAS
WOAT
WOAU
WOAW
WOAX
WOAY
Charleston, S. C.
Frankfort, Ky.
Hardware Co
William E. Woods
Webster Grove, Mo.
James D. Vaughan
Kalamazoo College
Portsmouth Radio Ass'n
Henry P. Lundskow
Bailey's Radio Shop
Boyd Martell Hamp
Sowder Boiling Piano Company
Woodmen of the World
Lawrenceburg, Tenn.
Kalamazoo, Michigan
Portsmouth, Va.
Kenosha, Wisconsin
Middletown, Conn.
Wilmington, Delaware
Evansville, Indiana
Omaha, Nebraska
Trenton,
Wolff
John M. Wilder
Penick Hughes Co
Franklyn
WOAZ
WPAC
WPAG
WPAH
J.
..-.-'
WPAK
WPAP
WPAQ
WPAR
WPAT
WPAU
WQAB
WQAK
WQAL
WRAA
WRAN
Donaldson Radio Co
Okmulgee, Okla.
Independence, Mo.
Waupaca, Wisconsin
New Haven, Conn.
North Dakota
North. Dakota Agricultural College
Theodore
R. A.
Winchester, Ky.
Frostburg, Md.
S. Phillips
General Sales
&
Engr.
Co
Ward
Kansas
Texas
Moorhead, Minn.
Beloit,
Saint Patrick's Cathedral
El Paso,
Concordia College
Southwest Missouri State Teachers' College
Appel-Higley Electric Co
Cole County Tel. & Tel Co
.
Rice Institute
Black
Hawk
Electric
Company
Grove City College
Penn Traffic Co
Ruegy Battery & Elect. Co.
Wright & Wright, Inc
WSAJ
WTAC
WTAU
WWAD
Jersey
Central Radio Co., Inc
Wisconsin Dept. of Markets
Doolittle Radio Corporation
WPAJ
New
Birmingham, Ala.
Stanford, Texas
.
"
.
.
Mo.
Dubuque, Iowa
Mattoon, 111.
Houston, Texas
Waterloo, Iowa
Grove City, Pa.
Springfield,
Johnstown, Pa.
Tecumseh, Neb.
Philadelphia, Pa.
The Grid
QUESTIONS AND ANSWERS
The Grid
is a Question and Answer Department maintained especially for the radio amateurs.
Full
be given wherever possible.
In answering questions, those of a like nature will be grouped
together and answered by one article.
Every effort will be made to keep the answers simple and direct,
yet fully self-explanatory.
Questions should be addressed to Editor, ''The Grid," Radio Broadcast, Garden
The letter containing the questions should have the full name and address of the writer and
City, N. Y.
also his station call letter, if he has one.
Names, however, will not be published.
answers
will
LOOSE COUPLERS
How does a loose coupler work without any connection
between tbe primary and secondary?
I have a set consisting
of a loose coupler, variable condenser,
crystal detector, fixed condenser and Turney )ooo-ohm phones.
no results at all. Could you help locate my trouble?
My antenna is of the T type; one end is about fifty feet high
and the other end sixty feet high.
I get
I enclose
my
hookup.
J. B.,
NEW YORK CITY.
a general way, electricity is transferred from the
primary of a loose coupler to the secondary by means
INof
a
phenomenon
traverses
a
called
induction.
Whenever
elec-
such as from the antenna,
through the coupler primary to the ground, magnetic
tricity
circuit,
lines of force, similar to those surrounding the poles of a
horseshoe magnet, spread out from the conductor, and
reproduce magnetically every fluctuation of the current.
When these lines of force cut an adjacent conductor, such
as the secondary of the coupler, they "generate" another
current which exactly follows the variations of the magncctic field, and therefore duplicates, excepting in strength
(there is a small loss) the antenna current.
Large generators in power houses operate on this principle, and are
nothing more than machines which pass a dense flux, at a
high speed, through windings from which the current is
drawn.
However, in a loose coupler, induction alone does not
explain the transference of energy from primary to secondary, for it is doubtful that with the low inductance (due to
the few turns of wire and the absence of an iron core), and
the comparatively great distance that often separates the
RADIO BROADCAST ADVERTISER
30O
20O
4OO
5OO
CHART
6OO
3OO
200
How
500
"J-OO
CHART
I
6OO
II
avoid amplification losses
when using radio frequency
BEFORE
quency
to
you purchase a radio fretransformer be sure to find
Does it show marked depresand peaks in the amplification range
between 250 and 500 meters? No amplithis out.
dinarily inaudible. The simplest and most elementary type of set, either vacuum tube or crystal
receiver type, will have its range tremendously increased.
sions
possible in such
Getting distant stations
becomes a gamble as to
whether or not there is
any amplification at a
fication
is
depressions.
The best rnethod
To SECURE maximum
of
use three stages
Amplification (R-2, R-3
and R-4), a crystal detector
and three stages of Acme Audio
Frequency Amplification. This
results
Acme Radio Frequency
maximum sensitivity
intensity, quietness in op-
insures
and
eration
given point.
tortion.
How
and freedom from
dis-
A small indoor antenna
or loop may be used and sufficient intensity obtained to operate the Acme Kleerspeaker,
providing perfect entertain-
to get uniformity
THERE
is a radio frequency
amplifying transformer which
has been so perfected that the
ment for a roomful of people.
e R-2 Radio Frequency Amplifying
Transformer. Price $5. (East
peaks and depressions are elimYou can get these and other
of Rocky Mountains.)
inated. This is the Acme R-2.
Acme Products at radio, elecThis unique transformer, after
trical andmany hardware stores.
long months of experimentation, has been perfected
Write for booklet R-2 showing proper hook-ups
with a special type of iron core and windings which
and other information.
eliminate the peaks and depressions and provide a
steadily increasing volume of amplification up to
the point of maximum importance 360 meters.
The Acme Apparatus Company
Gets greater distance
(Pioneer transformer and radio
engineers and manufacturers.)
EQUALLY
important is the far greater distances you
get broadcasting. The Acme R-2 used in a r*adio
frequency amplifier builds up wave energy before
passing it on to the detector. You hear signals or-
ACME
CAMBRIDGE, MASS.,
New
York,
Chicago,
.
.
.
184
.
U. S. A.
1270 Broadway
W. Washington
for amplification
Street
Radio Broadcast
350
windings, that more than a small fraction of the received
signal is transferred to the detecting circuit in this manner.
It is probable that the primary, acting as a transmitting
antenna energized by the received signal, wirelesses the
the stationary
and revolving
plates.
If
it
is
the fixed
condenser that is shorted, it is best replaced by a new one.
The receivers should be next tested by touching the ends
of the phone cord to the terminals of a dry cell.
If the
headset is in good condition, a loud definite click will be
heard.
Having once determined that the receivers are not
at fault, the phones themselves may be used for further
testing the set.
It is possible that the antenna is grounded and this
should be next ascertained by disconnecting the aerial
from the coupler and transferring it to one of the receiver
The remaining phone cord is grounded through a
dry battery. On making and breaking the connection, a
fairly loud click will indicate the difficulty.
The primary and secondary are next in order, and are
individually tested by connecting the phones to one end
of the winding, and the other to the switch lever through
cords.
=o
A VERY SIMPLE CIRCUIT
which the received energy is transmitted from
the primary coil of the loose- (vario-) coupler,
S,
P, to the secondary coil,
by induction
!n
energy to the secondary which is virtually a receiving
and which must be tuned to pick it up!
The advantages of the loose coupler over the single cirAside from permitting delicate and
cuit tuner are several.
aerial,
sharp tuning by slight changes in the coupling, which
simultaneously varies the wavelengths of the primary and
secondary, the coupler is very efficient in eliminating undesired signals, a quality known as selectivity.
If the
primary is tuned to a certain station, the antenna will
pick
up its wave with a partial exclusion of all others. But
same time, signals from a powerful or near-by trans-
at the
mitter, tuned to a different wave, will force oscillations in
the non-resonant circuit.
The secondary, which must be
the dry
lever
As the
cell.
on and
off
circuit is interrupted by running the
each tap, a loud click should be heard in
the phones.
The connections
between
the
various
instruments,
particularly soldered joints, should be carefully examined.
Inexperienced enthusiasts often use rosin as a poor subfor soldering pastes.
Aside from being an unsatisfactory flux, if the iron is slightly cool it will remain
between the metals, merely sticking the solder on with a
stitute
highly insulative glue, with the result that an ostensibly
After
perfectly soldered joint is no connection at all!
having determined that the condensers are not broken
down
or shorted, a battery substituted for the crystal detector will indicate, by a definite click, that the essential
secondary connections are well wired.
The last possibility is that the detector crystal may not
be a sensitive one, a condition that should be ascertained by
BUZZER
tuned to the same wave as the primary, will readily receive
energy induced by the tuned station, but will discriminate
against, and still further tend to eliminate, the forced
The primary and secondary are analogous to two
signal.
water filters. While some impurities may flow past the
first, few if any pass the second.
HUNTING TROUBLE ON A CRYSTAL RECEIVER
your antenna
is
not
all
HOW TO CONNECT
For use
that could be de-
(we suggest a single wire inverted L, from a
hundred to a hundred and fifty feet long), you should
certainly receive signals on your set, which is probably
the most efficient combination of instruments for crystal
One or more of several things may be at fault.
reception.
The condensers Ci and C2 should first be removed from
the circuit, one at a time in the order named, and the set
tuned after each removal.
If signals are received, it is
evident that one or both of the condensers is shorted.
in testing
A BUZZER
your crystal
set
sired
THOUGH
When
the variable capacity is at fault, the experimenter
can probably repair it by adjusting the relative position of
What Would You
The
Like to
buzzer test, an arrangement that is at any time a desirable
addition to a crystal set.
A small, high-toned radio
buzzer should be connected as here shown, where the
only deviation from the conventional announcing buzzer
hook-up is the single wire running from the stationary
contact to the ground lead on the receiver.
If the pushbutton is replaced by a telegraph key, the buzzer may be
used for code practice. The detector is adjusted while
the buzzer is vibrating, and the note will be plainly audible
in the receivers when the cat-whisker is on a sensitive spot.
Have
in
Radio Broadcast
?
would be pleased to hear from readers of the magazine on the following (or other)
The kind of article, or diagram, or explanation, or improvement you would like to
RADIO BROADCAST.
editors
1.
2.
What
has interested you most, and what
least, in the
numbers you have read
so far.
topics:
see in
Was this manual useful for you? yes no
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