broadcast - American Radio History
auGIsT,
BROADCAST
ENGINEERING
1962
iv
THE TECHNICAL JOURNAL OF ThE BROADCAST 174DUSTRY
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August, 1962
www.americanradiohistory.com
THE TECHNICAL JOURNAL OF THE BROADCAST INDUSTRY
VOLUME 4
AUGUST, 1962
NUMBER 8
ROBERT E. HERTEL, Publisher
EDITORIAL
GEO. H. SEFEROVICH, Director
JOHN BATTISON, Consulting Editor
D. F. BOICOURT, Production Editor
DUDLEY ROSE, Presentation Editor
Contents
ADVERTISING
New 20 Kw FM Transmitter
4
E. P. LANGAN, Director
R. J. HANCOCK, Manager
S. F. WILSON, Production Manager
Great Neck, New York
PAUL AND DON WEIL
260
A News Teletype Automatic Conelrad Alarm
.
Audio Studio Maintenance
IO
14
Northern Boulevard
Telephone HN. 6-0212
Chicago 1, Illinois
WILLIAM L. MILLER, JR.
E. F. LUKENS
307 N. Michigan Ave.
Telephone FRanklin 2-5944
Cleveland 16, Ohio
DAVID H. HERTEL
Wooster Road
Telephone EDison 1-2370
3100
Transistor Audio Amplifier Circuits
18
Omaha 14, Nebraska
BOB HOPKINS
Maenner Drive
Telephone 393-1905
1705
Stereophonic Phonograph Records, Phase
Relations and Stereo Broadcasting . .
Southwest
24
C. H. STOCKWELL CO.
4916 W. 64th Street
Mission, Kansas
Telephone RAndolph 2-4417
Los Angeles 57. California
MAURICE A. KIMBALL CO., INC.
2550 Beverly Boulevard
Telephone DUnklrk 8-6178
San Francisco 4, California
MAURICE A. KIMBALL CO.. INC.
580 Market Street
Departments
Room 400
Telephone EXbrook 2-3365
Paris
26
Engineer's Exchange
5,
France
JOHN ASHCRAFT
9 Rue Lagrange
ODeon 20-87.
London W. C.
2,
England
JOHN ASHCRAFT
30
Industry News
Bear Street
Leicester Square
WHitehall 0525
12
Tokyo, Japan
INTERNATIONAL MEDIA
REPRESENTATIVES, LTD.
Kasha Kurabu
14, 2-chome Marunouchi
Telephone (502) 0656
Book Reviews
35
Product News
36
B P'1
Index to Advertisers
40
Subscription Price: U. S. $6, one year; Outside U. S. A., $7. Single copies. 75 cents.
Adjustments necessitated by subscription
termination at single copy price.
BROADCAST ENGINEERING is published
monthly by Technical Publications, Inc. Editorial, circulation and advertising headquarters:
Classified Ads
40
Professional Services
40
Wyandotte St., Kansas City 5, Missouri;
telephone VIctor 2-5955.
Corporate Personnel: Robert E. Hertel, President; Frank D. Smalley, Executive Vice -President; E. P. Langan. Vice -President: Kenneth
Long, Vice -President.
Affiliated with
1014
HOWARD W. SAMS
CO.. INC.
BROADCAST ENGINEERING
2
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www.americanradiohistory.com
New 20 Kw FM Transmitter
Combination of two 10 kw units produces duplicate reliability
while maintaining full fidelity operation
THE BTF-20D
is one of the newest in RCA's growing line of FM
broadcast transmitters. All new
RCA FM transmitters have been
designed so that obsolescence is not
a factor when deciding to increase
power. The Type BTF-5B which
was introduced a number of years
ago can be used as a cornerstone
with which to change power and
advance to a BTF-10D or a BTF20D.
Compact High Power
The three cabinets of the BTF2OD fit into a space 104 inches wide
by 32 inches deep. The center cabinet contains the "Direct FM" exciter, BTE-10B; 400 -watt driver;
control and switching circuitry; and
dividing system to feed the power
amplifiers. On either side of the
center cabinet is a 10 -kw power amplifier. Two external high voltage
transformers can be placed in any
convenient location. The two power
amplifiers are driven in parallel and
the outputs are combined to supply
a full 20 kw to the antenna. With
the RCA BFA series of FM anten'
nas, up to 240 kw ERP can be obtained from the BTF-20D.
Figure I-The BTF-20D with front doors open to show tube
accessability and general appearance of the three bays.
4
Only f21 tubes (13 types) are
used in the BTF-20D. Eighteen
tubes (11 types) are used in the exciter, and from the output of the
exciter only three tubes in single ended circuits (a ceramic 4CX300A
in the IPA and a ceramic 4CX5000A
in each PA) are required to produce a 20-kw signal. In an emergency, the BTF-20D can operate
with a multiplexed 20 -kw output
with as few as ten tubes.
Emergency Provision
Depending upon the selection of
optional transmission line switching
equipment, it is possible to reduce
transmitter power to as low as 1
kw, or even to do maintenance on
one power amplifier while the other
remains on the air. Standard equipment on the BTF-20D is a powercombining diplexer and a reject load
rated at 1.5 kw. If there should be
an imbalance or failure of one PA,
the power in the reject load will go
above 1.5 kw, an alarm is sounded,
and the transmitter is automatically taken off the air. By addition
of optional transmission line switching it is possible to switch the still
operating power amplifier directly
into the antenna feed line to stay
on the air at reduced power. This
switching can be provided for manual or electrical changeover.
Extra Protection
If desired, a 7.5 kw reject load
can be installed in place of the 1.5
kw load. Thus, even if one PA
should fail, the transmitter will stay
on the air and programming will
BROADCAST ENGINEERING
By
Ivan H. Lubash
Broadcast Transmitter Merchandising
Radio Corp. of America
not be interrupted though output
power will drop to 25 per cent.
The transmitter has been designed for balanced input to each
power amplifier from the driver.
This is accomplished by tuning the
input matching meter for minimum
reading at each 10-kw amplifier.
Each power amplifier has its own
reflectometer for reading output
power and, VSWR;.in-addition there
is another reflectometer at the output of the combining diplexer
measuring power fed to the antenna.
Twenty kilowatts are easily provided at this point.
Each of the three cabinets contains its own separate blower for
maximum cooling. The plate power
to ,the driver stage is supplied by
the "dominant" power amplifier
(somewhat analogous to the way a
multivibrator begins to oscillate) .
If the "dominant" power amplifier
should fail, driver plate power is
automatically obtained from the
other power amplifier remaining on
the air.
The power amplifiers are identical even to the external high voltage transformers. This duplication,
since there is a constant reference,
makes servicing and trouble shooting quicker and easier. By comparing meter readings and by visual
comparison, faults can be corrected
in much less time than would otherwise be normal.
The IPA uses a ceramic 4CX300A
to produce 400 watts output to
drive the two power amplifiers. The
IPA stage is very similar to the one
used in the BTF-10C FM transmitArmen, 1962
Figure
2-The
BTE-103 FM Exciter
ter.' The 4CX300A IPA stage has
conventional pi -networks with variable capacitors in the input and
output stages. The variable capacitors act as the matching components, and tuning from 88-108 me
is accomplished by varying the inductances in the pi -networks.
Plate voltage for the IPA is obtained from the center tap of the
power supply of the "dominant"
PA. The "dominant" PA and the
IPA screen voltages work together.
If the "dominant" amplifier should
fail, automatic switching takes
place so that the IPA power is obtained from the second PA. The
IPA is protected by the overload
relays in the cathode circuit. Air
interlocks are provided to remove
plate ansi screen voltages if the
cooling it flow should stop.
Proven Design
Each power amplifier is essen-
for
use in
the BTF20/D.
tially the same as the proven power
amplifier in the RCA transmitter,
BTF-10C 2 The primary advance is
that efficient, long -life silicon diodes
have replaced tube rectifiers, each
power amplifier used the rugged
4CX5000A which is capable of supplying 10 -kw of power.
Easy to Tune
The input of each PA is a modified pi-network in which the input
capacity of the tube is shunted by
an inductive line to reduce the effective input capacity of the stage.
This inductance is also used to vary
input loading. A capacitor in parallel with the coil varies the inductive component of the circuit. Each
PA also incorporates its own separate grid bias supply for additional
stability.
Plate loading and tuning are
achieved by variation of two inductive line components in a pi 5
network arrangement. Tube capacity is shunted by the variable inductor. The pi -network has been
inverted for mechanical simplicity
which results in grounding one end
of the inductance to eliminate the
problem of insulating the variable
component from ground. However
the output line must be in parallel
with the inductance to bring it to
ground potential. This is done by
extending the output line down one
side of the inductive line.
Initial tuning is done by approximate setting of all variable components according to a tuning curve.
Final tuning is accomplished under
reduced plate and screen voltage
for circuit protection. The PA stage
is neutralized by variation of the
inductance in series with the screen
supply. Tuning across the 88 to 108
me FM band requires the change
of only one frequency -determining
part in each PA input circuit,
Special Filter
Each power amplifier feeds into
reflective type harmonic filter
which is not merely a second harmonic trap. No power is absorbed
in this filter which consists of an
M -derived half-T section, several
low pass filter sections, and a constant k, half -T section. Use of the
RCA filter assures compliance with
FCC requirements for spurious radiation. All harmonics through the
seventh are effectively attenuated.
The output of the two harmonic
filters is then combined in a broadband diplexer, and match a 31/8
transmission line. Total output
power is determined after this point.
Semiconductor Power Supplies
No tube rectifiers are used in the
BTF-20D transmitter. Semiconductor power supplies have been standard in the "Direct FM" exciter,
BTE-10B, since it was first introduced a number of years ago. Each
power amplifier in the BTF-20D
has six banks of heavy-duty silicon
a
Figure
3-Front
view of the
I
O
kw PA showing RF
cavity.
-
Figure 4-Close-up of the PA cabinet showing the solid state rectifiers. The
germanium screen supply is at the bottom of the figure, and the silicon grid
bias supply is central. The stacks at left form the high voltage supply.
6
diodes.
Regardless of application high
voltage, bias, low voltage, etc.-no
tube or selenium type rectifier is
used in the BTF-20D. As a result.
the BTF-20D has an extremely
wide operating temperature range,
-20 to +45 degrees C. This savings in heating requirements can be
reflected in the construction and
maintenance of the transmitter
BROADCAST ENGINEERING
PIONEERS
IN
TELEVISION
PROGRESS
New
General Electric
Switching
Systems
FOR LARGE OR SMALL
STUDIO AND MASTER
CONTROL REQUIREMENTS
Now General Electric offers a new
line of switching systems that are
designed to provide optimum picture
quality. Reflecting General Electric's
advanced design engineering, each
system can be integrated with existing
station equipment or incorporated
into new studio installations.
TS -2-B
TS -I
-A
SYSTEM
PRESET DIRECT TAKE OR PREVIEW
BANK (NOT USED IN TYPE TS -2-B
RELAY SWITCHING SYSTEM)
provides
TWO POSITION
DUAL FADER BAR
BANK
complete dissolve, fade, previewing, direct switching and
sync mixing facilities for
eight non -composite video
inputs and two composite inputs. Provisions
are also
available for special effects.
SPECIAL EFFECTS
'DUAL FADER) BANKS
Vertical Interval Switcher pro-
vides fast, transientless switching
during the vertical blanking interval.
Designed for use in medium or large
TV studios, the system permits studio
video switching or master video
switching of both monochrome and
color TV signals.
TS -1-A Relay Switcher system is particularly well suited for small to
medium -size TV studios, the system
permits studio switching of both monochrome and color television signals.
TC -59-A Direct Switcher provides the
maximum switching facilities in a
minimum size low cost unit. The
versatility of the system also makes
it especially practical for educational
and industrial TV applications.
In addition to the systems described,
General Electric will design and build
custom engineered switching equipments
to fit your particular requirements.
COMPOSITE
MCNITOR
provides complete dissolve, fade, direct
switching with preview moniTS -2B SYSTEM
toring and sync mixing
facilities
for
twelve non composite video inputs and
three composite inputs. Provisions are also available for
special effects.
WRITE-IN
COMPOSITE
OUTPUT BANK
STRIPS
PREVIEW
MONITOR BANK
iAr
.
PROGRAM
,..-(LINE BANK
R
tB
v
WRITE-IN
STRIPS
i l AF
\
s.wa
S-__
t
-'v-''
'-,
I ,1
BUTTON SPECIAL
EFFECTS (DUAL
FADER) BANK
12
NON -COMPOSITE
DIRECT TAKE
PUSH BUTTONS
12
3 COMPOSITE
DIRECT TAKE'
DUAL FADER
OUTPUT BUTTON
POSITION
DUAL FADER
BAR
FADER BAR
TALLY LIGHTS
TC -59-A
SYSTEM-This compact single unit construction
with low power consumption
provides complete dissolve,
fade, direct switching and
sync mixing facilities for four
non -composite video inputs
and three composite inputs.
_PUSH
BUTTONS
WRITE-IN
STRIP
I
-
PUSH BUrTONS
For complete information, contact your
nearest G -E Broadcast Equipment representative, or write to Technical Products
Operation, Broadcast Equipment Section,
Electronics Park, 212 W. Division St.,
Syracuse, N. Y.
551-03
GENERAL
www.americanradiohistory.com
ELECTRIC
building, particularly if the transmitter is to be remote-controlled.
Full Overload Protection
The only fuses used in this transmitter are in the crystal-oven heater circuits. Magnetically tripped
circuit breakers and overload relays
are used throughout for better protection. Time delay relays are used
so that plate voltage cannot be applied to the power amplifier tubes
until the filaments have properly
heated. Each amplifier is designed
to automatically come back "on"
twice after brief overloads. After
the third overload, the transmitter
will stay off. This feature will materially reduce "off -air" time due to
momentary overloads or brief failures in power fed to the trans-
SILICON
SILICON
SCREEN
H.V.
SILICON
BIAS
SUPPLY
SUPPLY
SUPPLY
REFLECTOMETER
i
S TERO
1
I`1ULTIPLEX
IGENERATORI
I
LBTI_IA _)
I
,
---J
E-BTX
PA
REFLECTOMETER
I
LOADT--jDIPLEXER
4CX 300A
ÁRRIER
IGENERATOR
HARMONIC
FILTER
REFLECTOMETER
BYE-IOB
EXCITER
SrtJB
10KWPA
4C X S000A
REFLECTOMETER
J
HARMONIC
FILTER
10KW PA
I
-IA
4CX5000A
REFLECTOMETER
SILICON
H.V.
SUPPLY
SILICON
SCREEN
SUPPLY
Figure
SILICON
BIAS
SUPPLY
5-Block diagram of
BTF20D.
mitter.
Built -In Remote Control
The BTF-20D is designed for remote control; no extra motor control or metering equipment is required. Terminals are provided for
remote control of transmitter on/
off, plate on/off, etc. Remote metering connections for each PA are
supplied as follows: cathode current, plate current, and power output. All RCA broadcast transmitters are designed to operate with
the BTR-11B or BTR-20 remote
control systems. This control equipment requires only two low-cost do
telephone lines (one each for control and metering) with a maximum
resistance of 5,000 ohms per line.
RCA remote control does not use
tones for control but instead uses
the principle of a switchable mo-
-+{
PLATE
TRANSFORMER
19.25
NO.1
TO
ANTENNA
HARMONIC FILTER
BROADBAND
DI PLEXER
HARMONIC FILTER
PLATE
TRANSFORMER
NO2
PLAN VIEW
---.+
24 MIN
mentary contact.
Direct FM Systems
The heart of the BTF-20D is the
time -proven "Direct FM" exciter,
BTE-10B 3 With this exciter, RCA
FM transmitters supply the widest
frequency response with minimum
distortion. Frequency response for
all RCA FM transmitters, including the BTF-20D, is from 30 to
15,000 cycles ±1 db. Harmonic distortion over the same range and
harmonics to 30 kc is 0.5% or less.
Consequently, RCA FM transmitters have the finest sound.
The "Direct FM" oscillator operates at 1/18 carrier frequency
(Continued on page
8
20)
HARMONIC FILTERS
LENGTH
OVERALL LENGTH
FRED.
TO
ANTENNA
68-98
MC.
98- 108MC.
140.29'
29.38°
I
-f3- ß-- 0
OPTIONAL
TRANSFER
PANEL
REDUCER
)F
O
cr
a
ELEVATION
Figure
6-Equipment layout and space diagram for RCA
BROADCAST
BTF20D.
ENGINEERING
UN-SEC Itli'1 INGRE1)I'T
Yet no other tapes have
You can look it up! Half a century ago, the precision
coating technology that forms the basis for today's
recording tapes was being developed by 3M. Then,
to this head -start in coating experience was added
pioneering research in magnetic recording. Resultthe first SCOTCH® BRAND Sound Recording Tapes
won practically immediate acceptance as the performance standard of the broadcast industry ... laid
the groundwork for' today's video tape recording.
In 1948, "ScoTcH" Recording Tape was first to offer
red gamma ferric oxide, precision -coated to acetate
backings (now a tape industry standard). And from
3M research came other notable firsts-acicular
oxide particles longitudinally oriented, Silicone
lubrication, polyester backings, high-output tape,
to name a few. Meanwhile, 3M manufacturing set
the pace for tape-coating uniformity, made possible identical magnetic properties throughout every
reel, and from one reel to the next. These advances,
too, proved a head -start for further developments.
it!
In 1956, the advent of commercial video tape recording equipment made dramatic new demands on tape
quality, required tapes to withstand heats and
pressures unheard of in audible range recording. 3M
not only provided the first practicable reels of video
tape it fulfilled pressing demands for this tape
-
in commercial quantity for the April, 1957, changeover to daylight saving time. In this way, "SCOTCH"
Video Tape helped revolutionize TV programming
with delayed telecasts across time zones.
What does this un -secret ingredient-leadership in
tape technology mean to broadcast engineers?
While others are striving to catch up with standards
of excellence already achieved for the industry by
"SCOTCH" BRAND products, 3M looks ahead to
further improvements and advances years beyond
the best that today's tape science can offer. Meanwhile, 3M offers "the tapes the professionals use":
"SCOTCH" Recording Tapes, audible range and
video, in the widest of choices for all requirements.
-
"SCOTCH" AND THE PLAID DESIGN ARE REGISTERED TRADE.
MARKS OF MINNESOTA MINING 9 MANUFACTURING CO..
ST. PAUL I. MINN. EXPORT: 99 PARK AVE., NEW YORK
CANADA: LONDON. ONTARIO. ® 1902. 3M CO.
August, 1962
magnetic Products Division
3
V
9
A NEW TELETYPE AUTOMATZ( CONELRAD
The new FCC requirements
of Conelrad alerts via the news
machine puts an extra strain on broadcast personnel. The unit described counts
ten bells only, and calls the operator or announcers on duty.
COUNTER
#I
25 MED -3
IOOWV7
COUNTER
#2 SW2
lO
RE SET
NC
RELAY #2
NO
25MF
NO
RESET
<
/NC
#2
;
25
MFDI
RELAY*FI
IOOWv
FROM
ALARM RESET
RELAY F5
_ ANC
J
SW4 NC j2
5MF
NEWS
TELE-
NO
ENO
PRINTER
ALARM
LAMP
X313
v
L
5W3
COUNTING
LAMP
(RED)
NO
TD2
NO
RESET
AMBER
2 SEC
COUNTERS
*313
25 MF
CONELRAD
100 WV
25MF
IOOWV
5WI
11
TO
REMOTE
ALARM
NO
1
RELAY
News Wire Alarm
Pat. Pend.
*4
RELAY#3
<NO
E- NC
NG
E-- NO
`,
WO)
10
SEC
-I TD
I. Relay circuits of alarm unit.
Note particularly reset circuits, and "bell
counters.''
Figure
=
BROADCAST ENGINEERING
10
www.americanradiohistory.com
Z PST
FROM
CONTROL
UNIT
(NO)
by AC
RELAY
ALARM
LAMP
(RED)
6V AC
ALARM
BUZZER
UNIT ON
LAM P
(GREEN)
By John Gort,
Chief Engineer
Western Electronic Associates
Clark, S. D.
THE
RECENT FCC action utilizing
the facilities of the news wire services to initiate CONELRAD alarms
and to disseminate CONELRAD
information, has placed a problem
on the doorsteps of the smaller
radio and television stations, in that
many of these operations do not
have newsrooms staffed on a Q4 hour basis.
The attention, or "CONELRAD
BULLETIN," signal is ten bells on
the news printer. In small operations, however, the announcer or
engineer-announcer could be on the
air, logging the readings of the
transmitter, or any one of a number of things that would take the
operators away from the newswire
machine, and thereby miss the ten
bell CONELRAD signal completely, and not notice the CONELRAD message on the newswire for
some time.
The unit about to be described
was developed by the writer for this
type of operation, and can very well
be used in larger operations. For
even in larger radio and television
operations, it is difficult to staff a
newsroom full time. The unit will
only recognize the ten bell CONELRAD signal, when in the proper
sequence. It will not recognize an
.5A
T3
117V6VAC
accumulated count of ten, such as
bells of five and five, or three, five,
two, or any other combination of
bells that make up a count of ten.
The unit employs mechanical counters, with automatic electrical reset
of the counters, should the number
of bells be other than 10, in which
case the unit resets itself and starts
over. The unit is normally placed
next to the news teletype, and is so
designed that the operator must
come back to the CONELRAD
alarm control unit, to reset the
alarm should the CONELRAD
alarm signal be received.
Figure 2. Red and Green alarm
lamps and buzzer in control room.
"mike" open, the operator can shut
off the buzzer, finish what he is
doing, before checking the teletype
machine. However, the newscaster
or operator will not be aware that
a CONELRAD message is on the
newswire teletype.
Circuit Details
Reference is now made to the
schematic of the CON E L R A D
newswire alarm. It is to be noted
that a pair of wires are labeled
"from news teleprinter." These run
to the newsprinter which has nothing more than a pair of SPST contacts that close when the upper case
Operation
letter "S" is transmitted on AssoA remote alarm panel equipped ciated Press machine, or the blank
with signal light and alarm buzzer space is transmitted on the United
is placed in the control room and
Press machines. The aforementioned
installed in the equipment racks. contacts are not normal equipment,
This unit, should a CONELRAD and have to be ordered installed on
signal be received by the control the respective newswire teleprinters.
unit, activates a locking relay that Attention is also directed to translights the signal light, and places the formers "T-1" and "T-Q." These are
buzzer in operation. The control 115 VAC to 12 VAC center tapped
room operator can disable the transformers so phased, and conbuzzer by switching off SW -Q; how- nected, that voltages add, making
ever, the signal light will stay on 24 VAC available for the relays,
until the master unit itself is reset. and 18 VAC available for the counSW -2 was included in the circuitry ters. Since 24 VAC is available at
so that should the alarm be acti- all points in the CONELRAD newsvated during a newscast, or with a wire alarm, No. 313 lamps, which
August, 1962
I
www.americanradiohistory.com
I
are rated at 28 volts are used
throughout.
The only non-standard items in
this unit are the electrical counters,
which were military surplus using
18 VAC for both the electrical
counting coils, and the electrical reset coil. The balance of materials
used is available on the industrial
market.
Switch No. 2 is included, so that
in the "IN" position, the alarm will
be triggered only by the 10 bell
alarm, when this switch is opened,
the alarm will be triggered by any
number of bells over 10. When a
count of 10 is registered by counter
No. 1 the normally open contacts
are closed and energize relay No. 2.
With this relay energized, the norcally closed contacts open and disables counter No. 1. This action by
relay No. 2 also closes the normally
open contacts and energizes relay
No. 5 which is a self-locking relay.
Closing the normally open contacts
keeping that relay locked in the
energized position, thereby feeding
24V to time delay No. 2, which
after two seconds, closes, and energizes the relay in the control room
alarm. The remote control room
alarm is very straight forward, it is
felt no additional explanation here
is necessary.
When any bell, or the first of any
series of bells are received, relay
No. 3, which is also a locking relay,
is energized through the action of
one set of normally open contacts
on relay No. 1. Relay No. 3 then
energizes time delay No. 1, a 10second delay, which in conjunction
with relay No. 4, will automatically
reset the electrical counters. Counter No. 2 is so arranged, that with
a count of 11 or more, the normally
closed contacts open, thereby opening the circuit of the counting coil
of relay No. 5, this prevents relay
No. 5 from energizing. Time delay
No. 2, which in turn would have
activated the control room alarm.
These units are presently installed
and operating at locations, using
both the AP and UP newswire services, and certainly fill a very urgent
need for continuous CONELRAD
alarm monitoring.
12
Figure 3. Front view of rack mounted alarm unit.
on
Figure 4. Rear view showing bell counters
rear of chassis, all components are husky
and take plenty of hard handling.
Figure 5. Operator's eye view of the
alarm unit in the control room.
BROADCAST ENGINEERING
Who wouldn't be proud of this
performance record?
A short time ago the engineering staffs of
some of America's leading Television
Stations were asked to comment on the
performance of the TDA 2 Video -Pulse Distribution Amplifiers they have in service.
Here is how they replied:
"A well engineered and built amplifier"
-
Crane, WGN-TV
Linn
"Very good. Intend to buy more"
P. Towsley, WMSB
"Good" Paul Adams, WCPO-TV
"Hope all transistorized equipment turns
100% satisfactory"
out this good.
Robert A. Holbrook, WSB-TV
"Good" R. J. Schroeder, KMTV
"Excellent" Roy Pratt, WHO -TV
"Like physical layout better than other DA
Keith Ketchum,
of the transistor class"
WOI-TV
W.
R.
-
-
-
-
"Will probably order more"
-
J.
E.
Risk,
KSD-TV
"A great step forward. We have 22 of
Rupert Bogan, WBAP-TV
them"
"Excellent" J. E. Mathiot, WGAL-TV
Nile
"A very fine piece of equipment"
-
-
-
Hunt, KCMT
"Excellent" Orrin Towner, WHAS-TV
"Completely satisfactory"
Clyde M. Hunt,
-
-
WTOP-TV
"Excellent. Will probably install several
more"
Ernest Vordermark, WJXT
Ray"Very satisfied with performance"
mond Boyd, KNOE-TV
"Does a very good job"
Byron Strong,
WSAV-TV
"Very good"
Joe Epperson, WEWS
"Nicely constructed and very good performance"
Phil Loeser, WTMJ-TV
"Very good. Will be used at NBC for interLeRoy Bellwood,
city microwave system"
KOGO-TV
-
-
-
-
-
-
One of the features of the fully transistorized
TDA 2 Video -Pulse Distribution Amplifier is the
low heat produced in its operation. fhe picture
shows Aaron Shelton, chief engineer of WSM-TV,
demonstrating that a standard 100 -watt light
bulb produces more heat than twenty TDA 2
amplifiers.
highly efficient and completely transistorized, including a
built-in regulated power supply. It replaces all existing vacuum -tube
types without altering cables.
Write or wire for descriptive technical data sheet on the TDA 2.
The TDA 2 is
*Circuit designec at
WSM-TV, Nashville
INTERNATIONAL NUCLEAR CORPORATION
P.
August, 1962
O. BOX 6171
NASHVILLE 12, TENNESSEE
13
AUDIO STUDIO MAINTENANCE
Cleaning is the chief preventive and remedy for
trouble encountered in maintenance of mechanical equipment.
A systematic plan of maintenance is required.
PART III (Conclusion) //
/
THE
MORE elaborate electronically regulated power supply system also
requires special consideration. It
usually consists of a conventional
rectifier followed by a series regulator (or pass tube) . Controlling the
gain of the series regulator is a do
amplifier, and a gaseous tube is used
as the reference for the regulator
section. The most rapid test of such
a supply is to measure its output
voltage under load. If an adjustment
is available it may be used to attempt to bring the voltage to its
recommended value. If this is not
possible, the various tubes must be
tested individually.
The rectifier and gaseous tube
may be tested as mentioned earlier.
The do amplifier and the series regulator must be checked for transconductance, as there is no way of
isolating each of them in the circuit.
This is especially true in the case
of two tubes used in parallel as pass
tubes, or a dual power triode (6AS7
or 6080, for example) in the same
configuration.
From the standpoint of preventive maintenance, economy, and
good engineering practice, there is
a further aspect of tube operation
to be considered. That is the practice of running the equipment continuously, 9.4 hours per day, seven
days per week.
It is asserted by many engineers
that the heating and cooling of
heater wires as equipment is turned
on and off each day shortens the
life of tubes. The author agrees with
14
By Thomas R. Haskett, P.O. Box 41-31762,
Michigan City, Indiana
this premise. He also agrees that
continuous operation results in less
costly and more reliable operation.
He has operated several radios and
amplifiers which were not turned off
for several years. The tube -life figures were astounding. Nine out of
10 tubes functioned efficiently for
at least 4000 hours (more than five
months) . Six out of 10 lasted 8000
hours (almost one year) , and four
out of 10 were still operating after
14,000 hours (nearly two years) of
continuous service. These were not
special-purpose, selected, premium,
or military types. They were common, ordinary receiving tubes.
The author has also observed the
performance of studio equipment, in
which some units were permitted to
run "hot" continuously, while others
were turned off each night. The
tubes which were hot at all times
did not fail as often as those which
were allowed to cool off every
night.
Assuming a station in which the
studio equipment is in use 60% or
more of each 24-hour day, continuous operation is highly desirable
from both the financial and the preventive maintenance standpoints.
The cost of the slight increase in
ac power consumption is negligible
compared with the savings in tube
replacement and labor cost. Moreover, this increase in power consumption is only a small percentage
of the present load. About the only
reason for such a system to be considered unfeasible would be in the
case of a station which uses its
equipment less than 60% of the day,
e.g., a daytime station.
Mechanical Maintenance
We have covered, at some length,
maintenance of the purely electronic aspects of studio audio equipment. But mechanical operations
need care, too. Cleaning is the chief
preventive and remedy for trouble
in this respect.
One of the most neglected items
in many studios is the cleaning of
tape heads. All capstans, rollers and
other surfaces which contact the
oxide side of the tape should be
cleaned, but the heads are most
susceptible to impaired performance, and even permanent damage.
This damage is due to the oxide
rubbing off the tape and piling up
on the metal surfaces. Oxide pileup can cause loss of high -frequency
response, uneven reproduction due
i o tape skew, permanent damage to
the head due to abrasion by the
oxide particles, and damage to the
tape, also due to abrasion.
Cleaning the heads and other
surfaces which contact the tape
must be done in a manner which
will not damage the delicate head
assemblies. Some cleaning solutions
leave undesirable residues, or even
react unfavorably with the assemblies. The best solution for head
cleaning is iso-propyl alcohol (available at most drugstores) . It is
about 93% pure, evaporates rapidly and leaves no residue, and will
BROADCAST ENGINEERING
not damage the heads. It should be
applied with wooden swab sticks
covered with cotton tufts ("Q Tips" or equivalent, also available
at most drugstores) . Use only such
soft tools; never use stiff brushes
to clean heads. The head -cleaning
operation should be performed at
least once each week on each machine, and perhaps more often if
the volume of tape use is high.
The drive systems of tape machines, including motors, idlers,
cams, gears and belts, should be
visually inspected and cleaned at
four-month intervals. Unless the
manufacturer advises otherwise, relubrication of all recommended
points should be done at this time,
also. The enclosures should be
cleaned, by vacuuming, blowing, or
brushing out before relubrication.
Where a metal -to -rubber or a metal to -cloth drive is used, the metal
surfaces should be cleaned with
alcohol after lubrication of the adjacent points. This will remove oil
and grime which might cause slip-
vacuumed or blown out, then oil
should be applied at all proper
points. The drive surfaces (usually
the rim of the platter and the shaft
of the motor) should be cleaned
with alcohol. Finally, a strobe disc
should be used to verify the speed,
and readjustment made, if necessary. The play-back cartridge, arm
and filter assembly should be
checked for continuity and quality,
by means of either a test -tone recording, or a recording of known
good quality. It is also advisable to
obtain a small magnifying glass with
which to inspect the stylus point;
if worn or chipped, it should be replaced. A written record should be
kept of the date of each such replacement; after a while it will be
possible to anticipate replacement
need due to a worn stylus.
Electronic Controls
Attenuators and potentiometers
will need infrequent cleaning, about
every six months. With respect to
the attenuators, the manufacturer's
instructions should be followed. The
usual procedure is to wipe clean
the surfaces contacted by the
fingers and apply "Davenol" (available by the attenuator manufacturer) . Care must be taken not to
bend or damage the fingers, as
page.
Turntable mechanical assemblies
should be cleaned and checked
every four months. The principles
are the same as outlined for tape
drive systems. Enclosures should be
Figure
smooth, noise -free operation depends on their positive contact tension. "Pots" of the carbon composition type should simply be squirted with control cleaner. If they are
sealed pots (A -B type) , of course,
they will need no cleaning.
The more jack fields and patch
cords are used, the less cleaning
they need. If they are not used
much, the plug tips and jack contacts will gather a film of dust.
Then when they are used, this dust
causes intermittent contact. Cleaning and continuity testing should be
done at least at six-month intervals.
The sleeves and tips of the plugs
and the fingers and contacts of the
jacks should be worked lightly with
crocus cloth until the metal shines
brightly. The simplest and fastest
continuity test consists of routing
a signal of known quality through
each jack and plug. The output
should be monitored on a good amplifier and loudspeaker while the
cord is flexed, and the plug and
jack tapped to check for intermit-
tents.
Microphones should be subjected
to rather close scrutiny at semiannual intervals. Mike cords and
plugs should be inspected for physical deterioration. A record should
5
Studio Maintenance Schedule
WOZ Radio
Months
Weeks
Complete FCC
System Proof
1 2 3
APR
MAR
FEB
JAN
4 1 2 3 4 1
2 3 4 1 2 3
DEC
NOV
OCT
SEPT
AUG
JULY
JUNE
MAY
1 2 3 4
2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
1
2
1
4
3
1
2
4
2
3
1
4
3
4
X
S
P
/
Console
Turntable and
Preamp 1
Turntable and
Preamp 2
Line or
Amplifier
C
P
¿I
ACCs
c
f
¿I
P
CL
C
4
P
P
L
c
L
U
St
s
e
s
1...P$
C
Tape 1
Tape 2
5
S
p
L
P
C
L
ó
P
L
s
c
/
s
u
P
c
L
r
Jack Fields
Attenuators
and Pots
<
Microphones
Code
I-Complete FCC System Proof
UP-Complete Unit Proof and Socket Voltage Check
SP --Spot Proof
CL-lean and Lubricate
C-Clean and Check
August,
1962
I5
www.americanradiohistory.com
be also kept of the approximate
gain of each mike. A practical
method of accomplishing this is to
record the average attenuator settings (of both mike fader and master fader) for several typical voices
on the station staff, in the course
of normal programming. If attenua tor settings change over a period
of time, a separate preamp should
be patched into the circuit to prove
whether the mike or the preamp is
at fault.
We have discussed individual
tests and maintenance operations in
detail. As recommended earlier in
this article, a systematic plan for
maintenance should be worked out.
Let us therefore review the operations to be done and the intervals
at which they are to be performed.
Every year: Run complete FCC
proof curves on entire audio system. Run complete proof curves on
each amplifier unit. Check all
socket voltages on each chassis with
VTVM.
Every six months: Clean and
time (in weeks) on the horizontal
axis, and on the vertical axis list
each item of studio gear mentioned
in this maintenance program. The
various annual, semi-annual, quarterly, tri -monthly and weekly jobs
can be juggled around so that each
week contains approximately the
same amount of maintenance work.
The chart should guide the staff in
performing the various tasks at predetermined times. A written log
should be kept of maintenance work
as it is done, containing the name
of the engineer doing the work, the
time and date, and his comments.
It will thus be possible for the entire staff to refer to this log and
be familiar with equipment performance and peculiarities.
The procedures described here
have been used for several years by
the author at a number of stations
where he has been employed either
as staff engineer or engineering consultant. During this time, the methods have proved their efficiency,
economy and reliability.
check all jack fields and patch
cords. Clean all attenuators and
pots. Check all microphones.
Every four months: Clean and
lubricate all turntable drive systems
and all tape drive systems; include
vacuuming or blowing out of enclosures and close visual inspection of
same.
Every three months: Run "spot
proof" of each amplifier unit; check
power supply voltages; vacuum or
blow out and make close visual inspection of each chassis.
Every week: Clean all tape heads
and capstans.
Exact details of the maintenance
plan will depend on a number of
factors: Amount of studio equipment, size of engineering staff, time
available for studio maintenance,
and whether or not transmitter
maintenance must also be done by
the same person or persons doing
the studio work. In any case, a
simple method of laying out a
maintenance plan is as follows: On
a sheet of linear graph paper, plot
Figure 6
1.40Z
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,
BROADCAST ENGINEERING
This is WBAL-TV's new building in Baltimore. The
exclusive use of Belden Audio, Camera, and Contro
Cables n this $2,04)0,000 studio bu lding helps main
tan the r h gh level of broadcasting efficiency.
Looking over part of this 125,000-foot Belden wire and
cable installation are John Wilner, Vice President: Engineering, Hearst Corporation, operators of WBAL-TV (left),
Manny Kann, Belden Distributor (center), and Hank
Hine, Belden Territory Salesman. All of the wire aid
cable for WBAL-TV was purchased from Kann -Eifert
Electronics, Inc., Belden Warehouse distributor.
WBAL-TV
Turns to Belden Exclusively for
Audio, Camera, and Control Cables
Belden manufactures a complete line of application -engineered
wire and cable for TV and radio broadcasting, recording
studios, remote control circuits, and similar applications. Call
your Belden electronic distributor for complete specifications.
Belden
WIREMANER FOR INDUSTRY
CHICAGO
SIINCE 1902
-
b-7.2
August, 1962
cord sets and portable cordage electrical
power s4.pply cords
household cords magnet wire lead wire automotive wire ano
welding cable
cable aircraft wires
17
Transistor Audio Amplifier Circuits
PART
This series on transistors is based on a Solid
I
Donald K. Haahr
Engineering Department
Collins Radio Co.
Cedar Rapids, Iowa
By
SOLID
STATE
theory
is
relatively
new. Bell Laboratories began exposing it 12 or 13 years ago and
transistors have been in quantity
production for the past seven or
eight years. Today, transistors and
their application are not well understood for two major reasons:
1. Many engineers feel the job
can be done with vacuum tubes, so
why waste time on anything else,
and
2. Lack of understanding makes
almost anything complicated.
So far, there has not been too
much concern with Solid State devices in broadcast engineering for
several reasons. For example, a one
kilowatt transmitter is put into a
package four feet wide, three feet
Stab
Short Course given at University of Nebraska
and gives basic transistor circuit desgn data.
deep and six feet high while the Air
Force puts a one kilowatt power
amplifier in a six-inch cube. Also,
everyone is familiar with studio
quality tube type audio equipment
works well, so why go to the
expense of changing it to something
everyone doesn't quite understand
and hit the budget for new equipment and training programs for the
technicians? But when it comes to
efficiency, reliability and replacement costs, the picture starts to
change. A decision has to be made
on what is economy and what may
be false economy for the situation.
There is one phase of broadcasting and telecasting where semiconductors are making themselves
worthwhile. This is in remote pro -
-it
o+
fQ4rrE.eY
gram work where size, weight and
sometimes power consumption become important. For instance, the
Collins 12Z-2 Remote Amplifier
weighs 45 pounds and the transistorized 212Z-1 Remote Amplifier
weighs 21 pounds. The latest model,
the transistorized Collins 21211-1
Remote Amplifier, weighs 11 pounds
and operates on flashlight batteries
at a cost of less than one cent per
hour.
Thus, semi -conductors do apply
to broadcasters whether the industry is ready for them or not. Advancements will continue, and
broadcast equipment manufacturers
will design and develop equipment
to meet the new needs and desires
of the broadcast industry.
The following are a few detailed
specifications broadcasters might
look for while evaluating different
pieces of broadcast and TV audio
equipment:
Temperature
our
o
.1
specifications are
important in remote equipment because large capitanee electrolytics
often fail at low temperatures and
go into thermal -runaway at high
temperatures. A reasonable temperature specification for remote
equipment is -20° C to +50° C,
-4° F to +122° F in more familiar
terms.
/N
Figure I. Line Amplifier.
In transistor circuitry, it becomes
more important to know the input
and output impedances, and whether the circuitry is balanced or unbalanced. Unbalanced circuitry is
common because it is more economical and very often adequate.
BROADCAST ENGINEERING
18
www.americanradiohistory.com
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made at 10 db above rated VU output to assure no distortion on audio
peaks.
Response produces a difficult
specification, but there aren't too
many things to watch for. First,
use a 1,000 cycle reference (400
cycles is no longer standard) and
second, ensure that tests are run at
full rated power output.
Distortion is also tricky if full
rated power output is not used, and
here frequency becomes important,
too. Low frequency distortion is
often caused by inadequate transformer size, while phase shift is a
high frequency offender.
Noise is a double barreled specification when comparing equipment.
The signal-to-noise ratio, or the
noise level below the full rated output, is the important, final concern.
The equivalent input noise level is
the sum of the noise level below
calibrated output (-60 db) and
the input (-50 dbm) . This -110
db tells us that the best signal-tonoise ratio for a -70 dbm microphone input would be -40 db
(-110 db less -70
-40 db),
which is important in choosing a
microphone-amplifier combination.
There are mechanical limitations
of transistor audio circuitry to be
aware of, too. A greater variety of
mountings is available for transistors than for tubes. The least expensive method is support by the
transistor leads through tubelets, or
to terminal stakes. This may be improved by inserting the transistor
in a hole in the printed circuit
board and further by a nylon saddle (important where vibration and
shock are critical) . Clips and heat
sinks are used when needed.
Transistor circuits usually justify
printed circuits because of quantity
production, generally small size and
reliability. A printed circuit board
enjoys the advantages of economical, uniform and reliable assembly
-less chance for human error.
However, it has the disadvantages
of requiring a less familiar trouble
shooting technique, is expensive on
short run projects, and it is difficult
to make minor production changes.
It might be well to review some
of the printed circuit board materials. The XXXP, or paper phenolic, costs about $1 a square foot,
-
9
_
.`l
.
IIIIIIIIIIIBIIIIMIII
Ñm=raam
o
Figure 2.
Response -Phase Versus Frequency
(of the line amplifier)
Levels
Care should be taken to note the
reference levels when comparing
audio equipment. Some of the input
level terms are db, dbm, millivolts,
dbv, sound pressure of 1 dyne per
square centimeter or 10 dynes/cm2,
across various loads or unterminated, open circuit voltage and
others. For designing a preamp or
buying a microphone, it could b
important to know if the -70 db
microphone output rating was referenced to 1 volt, open circuit, with
a sound pressure of 1, or a sound
pressure of 10 dvnes/cm2, which
means a 20 db difference.
Output levels are usually in dbm
August,
1962
because 600 ohms impedance is
common in broadcasting and meters
are calibrated for this at a reference of 1 milliwatt. One should be
sure of the 600 ohm termination
though, together with balanced or
unbalanced circuits, and if the rating is before, or after, an isolation
pad. We then come to the terms db
and VU. A complex signal, such as
audio, is measured in VU, never in
db. Tones are measured in db and
1,000 cycle tone of 0 dbm = 0
VE Hoowever, the peaks of a corn fix signal are approximately 10 db
above this. For this reason, in testing, the VU meter is either switched
off, or disconnected and the tests
a
(Continued on page 22)
19
FM
Transmitter
(Continued from page
OVER 1400 SIZES AND TYPES OF IERC HEAT-
DISSIPATING ELECTRON TUBE SHIELDS
ARE EFFECTIVELY COOLING MILLIONS OF
TUBES, EXTENDING LIFE AND RELIABILITY,
REDUCING DOWN -TIME AND MAINTENANCE
COSTS IN THOUSANDS OF MILITARY AND
INDUSTRIAL ELECTRONIC EQUIPMENTS!
Write ioda} for the fact: on how +ou can im,crove egcipment
reïiab'ity with IERC Heat-Jis.srpating Tube Shields.
IERC "AL
ui
International Electronic Research Corporation
135 West
Magnolia Boulevard, Burbank, California
oreign Manufacturers: Europelec,
'aril,
"ranee. Garrard Mfg. & Eng. Co
,
_td., Swindon, England
8)
(5-6 mc) . There are only three frequency multipliers in the circuit,
thereby keeping distortion to an absolute minimum. The only tubes
that have any effect on the quality
of the signal are the seven in the
modulator, oscillator, subcarrier input, and frequency multiplier circuits. The remainder of the tubes
in the exciter are in the AFC and
"off -frequency" circuits. In the
event of a failure in the latter circuits, they can be switched off and
the carrier kept on the air with
manual frequency control.
The BTE-10B is easy to tune and
maintain. All the circuits in the
"Direct FM" exciter are single tuned to reduce the number of tuning adjustments. The RCA exciter
has a built-in multimeter and oscilloscope to simplify tuning, trouble
shooting, and maintenance.
An "off -frequency detector" automatically removes plate power from
the final amplifier (s) to prevent
the transmitter from operating beyond frequency limits. Actually, the
"off-frequency detector" is a phase
detector that compares the reactance modulator with a constant
crystal source. As a result. "Direct
FM" frequency stability is determined by the reference crystal
oscillator.
Multi -Channel Operation
The BTF-20D has been designed
and proven for stereo and SCA operation. The RCA stereo subcarrier
generator, BTS-1A, can be used
with the BTF-20D for FM stereo
operation. In addition to stereo, an
SCA channel can be operated
simultaneously by adding the BTX 1A subcarrier (SCA) generator. If
the station does not broadcast
stereo, two SCA channels can be
transmitted simultaneously.
The subcarrier generators along
with other associated equipment
can be placed in optional accessory
equipment rack designed to harmonize with the appearance of the
BTF-20D. The accessory equipment rack can be placed on either
side of the transmitter. The rack is
complete with full front and back
hinged doors.
BROADCAST ENGINEERING
20
www.americanradiohistory.com
all -transistorized
New Sony Sterecorder 777
the first/complete/portable/all-transistorized/high fidelity PROFESSIONAL RECORDING & PLAYBACK SYSTEM
The most advanced achievement in recorder engineering to date, the superb new
remote -controlled professional Sterecorder 777 series features the exclusive and patented
Sony Electro Bi -Lateral 2 & 4 track playback Head, a revolutionary innovation that
permits the playback of 2 track and 4 track stereophonic or monophonic tape without
track width compromise through the same head!
Included in an array of outstanding features are individual erase/record/playback
heads, professional 3" VU meters, automatic shut-off, automatic tape lifters, an all solenoid, feather -touch operated mechanism, electrical speed change, monitoring of
either source or tape, sound on sound facilities, and an all -transistorized military plug-in
type circuitry for simple maintenance. The three motors consist of one hysteresis
synchronous drive motor and two hi -torque spooling motors.
Unquestionably the finest professional value on the market today, the 777 is available in two models, the S-2 (records 2 track stereo) and the S-4 (records 4 track stereo).
Both models can reproduce 2 and 4 track tapes.* And, the Sterecorder 777 models will
integrate into any existing component system. $595 complete with portable case and
remote control unit.
-
*Through the exclusive Sony Electro Bi -Lateral 2 and 4 track playback head.
All Sony Sterecorders
are Multiplex ready!
SUPERSCOPE
The Tapeway to Stereo
www.americanradiohistory.com
Sony has also developed a complete port-
able all-transistorized 20 watt speaker/
amplifier combination, featuring separate
volume, treble and bass controls, mounted in
a carrying case that matches the Sterecorder
777. $175 each.
Also available is the MX -777,a six channel
all -transistorized stereo/monophonic mixer
that contains six matching transformers for
balanced microphone inputs and recorder
outputs, individual level controls and channel
selector switches, Cannon XL type receptacles,
a switch to permit bridging of center staging
solo mike. $175 complete with matching carrying case.
The first/complete/portable/all-transistorized/high fidelity/professional recording fd
playback system: $1120 complete.
Sold only at Superscope franchised dealers.
The better stores everywhere.
For additional literature and name of
nearest franchised dealer write Superscope,
Inc., Dept. B, Sun Valley, California.
mechanically supported properly.
Component coating is not generally
needed in broadcast applications.
Transistor Circuits
(Continued from page 19)
paper epoxy about $2 a square foot,
glass epoxy $3 a square foot and
Teflon about $15 a square foot.
Teflon is used only where extreme
vibration, as in aeronautical equipment, is present. Glass epoxy is far
superior to the paper type mechanically, but electrically about the
same. In other words, it is possible
that all can meet the needs of
broadcasting provided they are
Transistor Circuits
There are three general methods
used to connect electrically a transistor to the circuit. A socket allows
easy exchange of transistors and
easy removal for circuit resistance
checks, but leads on some transistors and socket connections tarnish,
and the transistors may shake out
during transportation. A tubelet
soldered connection is good elec-
MC MARTIN
TBM 3000
FM MONITOR
APPROVED
BY FCC
The newest and most up to date Monitor on the
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Immediate delivery (after thorough checkout and
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Price: $495
For the very finest in reliability and performance,
depend on McMartin FM and Multiplex Monitors
COMMISSION
COMMUNICATIONS
C5. O C
FEDERAL
WASHINGTON
March
.00a'Zo.Es'«:.ÄYT,"
26, 1962
,N
wERY H6EA
Y0:
6179
Inc.
McMartin Industries,
Street
1612
California
Omaha, Nebraska
Attention:
Mr. Ray
B. McMartin
President
Laboratory,
Commiasion'8
bolos for
at the
listed
Gentlemen:nducequipment
Comis
te
of
On the bares
tests
issuedthe
pproval isPherebyof
art 3
ion under
operation
to
the
u covering
Rules:
Commission's
(FM Broadcast)
Frequency Monitor
Industrie°, Inc.
McMartin
TBM-3G00
Make: orc'tRpe:
e:T988
megacycles
to 108
ency
Number: 3-113
FCC Type Approval
Kind of
Originality by
McMartin Industries, Inc.
1612
California Street
Omaha, Nebraska
in Canada, Sold by: Canadian Marconi Company. Montreal 16, P. Q.
trically, but maintenance is more
difficult and the transistor is usually damaged when removed. The
most reliable method is leads soldered to a terminal stake. However,
caution should be used so that no
more than two connections are on
the stake and the transistor lead is
soldered on last.
Bias stability isn't new; in fact,
it is taken for granted in tube circuitry. However, the current, voltage and impedance values used in
transistor circuits warrant more
concern and care. For example, voltages are in tenths rather than tens,
30s rather than 300s, and impedances are in thousandths rather
than megohms.
One thing that is different and
important' is that transistors are
temperature sensitive. As a result,
it is advisable to establish bias stability in the form of a voltage
divider, independent of transistor
operation. When a transistor temperature increases, whether through
operational power dissipation or
ambient equipment temperature,
the temperature of the transistor
continues to increase, and results in
thermal -runaway. This can quickly
damage any transistor-with no
visible change. Maximum junction
power temperature is critical, so
case size, potting compound and
heat -sinks become important. In
addition to thermisters, a germanium diode may be used with a
germanium transistor to produce a
temperature coefficient that can
vary a stage's bias and increase the
operating temperature range.
It is interesting to note that both
transistors and tubes depend on circuit applications for input and output impedances. For example, typical transistor input impedances of
40 ohms, 2,000 ohms or 120,000
ohms, and output impedances of 2
inegs, 4,800 ohms, or to 2,000 ohms
are shown in typical circuits in the
NAB Engineering Handbook.
This leads to another circuit
characteristic of low emitter resistances in the order of 500 ohmswhich are not uncommon. To prevent degeneration or current feedback, the emitter resistance must
be bypassed and with the usual bypass impedance to emitter resistance ratio of 10: 1 at 20 cycles this
means about 200 microfarads are
required. We are thankful to
BROADCAST ENGINEERING
22
www.americanradiohistory.com
Sprague, Aerovox and others for
developing high capacitance, low
voltage condensors.
Transistors as well as vacuum
tubes have the same reasons for
utilizing feedback: improve response, reduce distortion and possibly noise, vary impedances and
increase temperature stability-but
all at the expense of gain. Try for
a compromise with the "rule of
thumb" that says for the stage involved, 6 db feedback could cut
distortion in half and increase the
response almost to the 6 db point
on the no -feed-back curve. Both signal and noise are reduced, but their
ratio is unchanged.
The two common types of single
stage feedback are:
1. Series, sometimes -called current feedback, which is unbypassed
resistance in the emitter circuit, and
2. Shunt, sometimes called voltage feedback, which is a resistance
from collector to base. Each has its
own advantages and disadvantages.
Incidentally, the shunt feedback resistor also forms the bias stability
voltage divider mentioned earlier.
Feedback around a single stage
is the easy way to stay out of
trouble but quite expensive in terms
of gain. For example (Fig. 1) , assume three stages have an equal
and over-all distortion of 8%.
Ideally, 6 db of feedback around
each separate. stage reduces overall distortion to 4% at an 18 db
gain sacrifice. On paper, a 6 db,
3 -stage feedback loop will offer 6 db
correction to each stage for only a
6 db gain sacrifice, and this is possible, leaving a 12 db gain advantage. This is well worth investigation. However, look at the response
and phase shift of this amplifier
with no feedback.
These curves have been seen before in amplifier design (Fig. 2) ,
but their importance is not always
fully recognized. They can explain
why amplifiers oscillate or oscillators won't depending on which
they are not supposed to do. For
example, to make an oscillator from
this circuit, take an output feed of
proper phase, return it to the input
as positive feedback, tune it to 1 kc
and it would work well. However,
if this were to work at 50 kc, the
feedback would be 180° different
and become the negative feedback
tried for in an amplifier.
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Portable demonstration units
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The
lime -tested
compact play bad or combination ur it for
tont; of roam or
Remote Control Unit
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Equalized Turntable Preamplifiers
-
For the best and most modern broadcast systems
and supplies, look to VISUAL-your SOURCE for
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CORPORATION
pennsylvania 6-5840
August, 1962
www.americanradiohistory.com
STEREOPHONIC PHONOGRAPH
RECORDS, PHASE RELATIONS
AND STEREO BROADCASTING
By
H.
E.
Roys, RCA
Victor Record Division
ing where monophonic reproduction
is the sum of the left and right (L &
R) channels. The phase relationship
is of importance since an incorrect
phasing will result in considerable
cancellations, particularly at low
frequencies. Only if the proper phasing has been observed, will the
sound quality be satisfactory.
Evaluating Stereophonic Records
A simple method of judging the
monophonic quality of a stereophonic record is to reproduce it
monophonically. This may be
Stereophonic recordings involve two separate channels of information. In order to achieve the acoustical perspective,
depth, spaciousness and other benefits that are possible, great
care must be observed to maintain the proper phase relationship between the two channels of information, both in recording and reproduction.
45°-45° stereophonic system
chosen by the Record Industry Association of America (RIAA) as a
standard was selected after careful
consideration of the available systems. It was selected, for one reason,
because of the compatibility that
can be achieved with respect to
monophonic reproduction. To
achieve this, the RIAA standard
states:
In 45°-45° stereophonic disc phonograph records, equal and in -phase
signals in the two channels shall
result in lateral modulation of the
groove.'
As illustrated in Fig. 1 for the
45°-45° system, the two channels
of information are recorded in a
single groove with the modulation
axis of the two systems at right
angles with respect to each other,
and 45° with respect to the surface
of the record. The diagrams at the
left and right, A & B, show the type
of groove obtained when an identical signal is applied to the left and
THE
24
right coils separately and then together. It is important to note that
in Fig. 1-C vertical modulation results if the signals are equal in amplitude but out of phase. Likewise,
Fig. 1-D shows that lateral modulation results if the two signals are
equal and in-phase.
In terms of record reproduction,
if in case of 1-D the recording is
reproduced with a suitable lateral
pickup, information from both channels will be present. The sound
quality will be like that of a monophonic record that had been cut
with a lateral recorder where the
signals had been obtained by combining the output of the two channels electrically. If the phase is reversed, as is the case shown in Fig.
1-C, the modulation of the groove
will be vertical and the results will
be poor due to cancellation of the
lateral components.
The problem of correct phasing
is similar to that which must be
observed in stereophonic broadcast-
achieved by using a suitable lateral
pickup and reproducing the record
over a single channel amplifier and
speaker system. By suitable is
meant a pickup designed for monophonic record reproduction, one that
has sufficient vertical compliance to
properly track the vertical undulations of a stereophonic record without undue distortion or damage to
the groove. A stereophonic pickup
with the output leads tied together
for monophonic reproduction provides a ready means of providing
such a pickup.
Another method and one that
might offer greater appeal to the
broadcaster is to combine the outputs of the two pickup channels at
the outputs of some of the amplifiers along the chain. When doing
this, there may be some question
about the channel gains and the
phase relationship. These may be
easily checked by playing a lateral
frequency record. The VU meter
readings for each channel should be
equal. If the phase relationships are
incorrect, the single VU meter that
reads the combined outputs will
show a drop in output as the channels are connected together. The
cancellation of signals due to improper phase relationship when reproducing music records results in
a loss in the low frequencies and
undesirable high frequency characBROADCAST ENGINEERING
SIGNAL ON
LEFT COIL
RIGHT DRIVE
COIL
` \ \\
ONLY
SIGNAL ON
RIGHT COIL
ONLY
LEFT DRIVE
COIL
\ \
//
EQUAL SIGNALS
BOTH COILS
EQUAL SIGNALS
BOTH COILS
180'"OUT OF PHASE"
/7 C.
FIG.
2V
"IN PHASE"
UTTING
STYLUS
145° 45°
D.
\\
/
/
STEREO DISC RECORDER
AMP
hi I
o
o
If
AUDIO
OSCILLATOR
o
AM
OSCILLOSCOPE
FIG.2 PHASE INDICATOR
LOUDSPEAKER
AMP
o
o
f
FIG3 CHECKING AMPLIFIERS
AMP
MICROPHO ES
-o
o
o.
o
AMP
O
o
O-
FIG.4 CHECKING MICROPHONES
FIG.5 CHECKING LOUDSPEAKERS
teristics. When the phase and gain
relationships are correct, a properly
recorded stereo record will show
nearly undetectable tonal balance
differences between monophonic and
stereophonic reproduction. The
stereo reproduction will, of course,
exhibit a c co us t i ca 1 perspective,
depth and spaciousness due to the
additional information since it is derived from two channels instead of
one.
Phase Checking Methods
Realizing the importance of observing and maintaining the proper
phase between the stereo channels,
a logical question that arises is how
can one check the phase relationship. Ideally, the two channels
should be exact duplicates throughout their operating range. FreAugust, 1962
quency and phase response should
match closely. In general, the phase
relationship is the most difficult one
to measure. However, with the aid
of an audio oscillator and an oscilloscope, simple observations can be
made that will determine whether
or not the connections are in -phase.
IF an audio oscillator is connected
to an oscilloscope, as illustrated in
Fig. 2, with the high side of the
oscillator connected to both high
side terminals of the oscilloscope, a
straight line inclined at a 45° angle
to the right should be observed.
Since this is a common signal equal
in amplitude that is being applied
to the oscilloscope, it is obviously
the in -phase condition. If two signals of the same frequency and amplitude were applied 180° out of
phase, a 45° line would be observed
which would slope towards the left.
A 90° phase shift would result in a
circle.
The oscillator and oscilloscope
provide a simple set of tools for
determining the "in" and "out" of
phase conditions. They may be used
for microphones and loudspeakers as
well as amplifiers. The arrangements
for such measurements are shown in
Figures 3, 4 and 5. When acoustic
transmission is involved, a low frequency such as 200 cycles should
be used to minimize phase differences due to the transmission of the
signal through air. When checking
loudspeakers as illustrated in Fig. 5,
a quick check of the system can be
made by first placing both microphones in front of one loudspeaker
and noting the trace on the oscilloscope. The same trace should result
when the microphone is shifted back
to its original position. For checking
the phase relationship of high frequency speakers, EIA' recommends
that direct current be used and the
direction of motion of the diaphragm
be observed, or a sensitive do meter
be connected across the terminals
and the polarity of the voltage noted
when the diaphragm is moved
manually.
Conclusions
quite likely that in the beginning FM stereo broadcasts will
be heard largely on monophonic receivers. In order to retain public
acceptance, it is necessary that the
quality of the monophonic reproduction be equivalent to that obtained
from monophonic transmission.
Phase relationships of the signals of
the two channels are important.
Stereophonic records made in accordance with RIAA standards will
provide program material suitable
for both monophonic and stereophonic reproduction.
It
is
(1) RIAA Engineering Bulletin E-3.
(2) EIA Standard RS-233 "Phasing of Receiver
Loudspeakers"
25
i
A Muting
Amplifier for
SCA Systems
By Lloyd Jones
Santa Barbara, Calif.
Many FM stations are transmitting background music in addition to their monaural or stereo
broadcasts. They need a muting
system for their SCA carrier (67kc)
to reduce the possibility of some
cross -talk in between selections.
Some background music is con -
67KC
67 KC
OUT
.01
IN
.01
47K
2.K
B
ti
+200V.
300
22K
20-20
10."-
@250
V.
SI.D.
bI
AMP
trolled by 25 CPS tone to start and
stop the machines. The muting amplifier shown in Fig. 1 is very simple
to construct, simple to adjust, and
works very reliably, dropping out
only when the music level reaches
about 25 DB below normal program
level. When 25 CPS tone is used
the filter shown reduces the tone by
about 30 DB, therefore the tone is
also muted. None of the parts were
critical. The input and output connectors, type of chassis, pilot lamp,
etc., are left to your own choice.
The system shown is used with
Browning and McMartin receivers.
The results are excellent.
A note regarding any multiplex
SCA receiver. Put a scope on the
grid of the second mixer tube. If
you see the 67 KC signal plus other
signals such as the stereo 19kc pilot
carrier as well as the IF of the receiver you can expect to have crosstalk troubles. Remove the grid input
lead feeding the grid of the second
mixer tube. Install a simple filter
consisting of one Thordarson HS -6
"horizontal oscillator coil" and two
47 pf condensers, plus sufficient
capacity to resonate the HS-6 to
67kc. See Fig. 2.
117 VAC
IM
TRIAD
R-30 X
10K
Suggestions
20 @ 250
.01
V TC
S
on Tube
-IS
25
Replacement
CPS
FILTER -TT ELECTRONICS
CULVER CITY. CALIF.
MUSAK
By
5055
i-4VU
Fig.
I. SCA Muting Amplifier. Condensers are shown in mfd. Resistors are
shown in ohms, 10%.
I. F
47 PF
47PF
HS -6
SECOND
MIXER GRID
_AM
C- RESONANCE
@
Fig. 2.
Hampton C. Clark, Jr.
67KC.
Filter to prevent unwanted IF and 19 KC stereo pilot carrier from
reaching grid of second mixer tube of multiplex receivers.
As long as a tube performs its
required services properly, it should
not be replaced. In some cases,
where there is a great deal of complex equipment, and the engineering
personnel is not very highly skilled
periodic tube checking with a mutual conductance tube checker is
almost a necessity. By logging the
conductance readings periodically,
you can tell when a tube is going
bad, and such tubes can be replaced
if they show any sudden change.
Also, such checks will frequently
turn up tubes that have burned out
filaments which might cause errone--
BROADCAST ENGINEERING
26
www.americanradiohistory.com
FREE HELP FOR PLANNING
Path Surveys and Site Selection Manual
Profile Planning Charts
Antenna System Calculator
Graph Worksheets
Protractor
System Planning Charts
Map Symbols Guide
LEGEND
4
FEDERAL
STATE
_,
HIGHWAY
HIGHWAY
enaM SD MARKET
NWT
PLANNING STL or INTERCITY RELAY THIS YEAR?
SEND FOR RAYTHEON'S FREE PLANNING KIT!
Raytheon's Microwave System Planning Kit helps you
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In designing this Planning Kit for TV Station Chief
Engineers, Raytheon experts drew on their extensive
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Raytheon KTR Microwave, for Intercity Relay network
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MAIL TODAY FOR FREE PLANNING KIT
Raytheon Company, Dept. GM4-BE, Norwood, Massachusetts
Attention:
H. Bannon
Please send free Microwave System Planning Kit.
Planning
a
system.
Keep me on mailing list.
Name
Title
Company
Address
City and State
Have Engineer call.
For reference only.
BE -8,
ous readings on such things as frequency monitors, even though the
malfunction might not be obvious
from merely taking meter readings.
If the small broadcasting station
can afford to replace all tubes periodically, and wants them replaced
that way, it is wise for the engineer
to follow the management's instruction. It is also true that if you replace all tubes periodically, you will
be scrapping many tubes that are
perfectly sound and consequently
wasting a great deal of your employer's money. Still, if your employer insists on this, it behooves
the engineer to do as instructed, or
he may find that the engineers at
that station are periodically replaced!
Having done considerable hamming, on a limited budget., I have
obtained most of the tubes for my
equipment from the scrap boxes of
radio shops, and from radio stations
where I worked. Many of the tubes
were in perfect condition, others a
bit low on emission, but suitable as
audio amplifiers. Many of these
tubes lasted for months and months
-some even years. Sometimes a
shorted tube can be restored to service by inverting it, banging it gently
against a table top, and replacing
in its socket. This method is worth
a try.
As to transmitter tubes, if you
notice that the RF finals show a dip
in plate current on modulation
peaks, there's a good chance that
the high voltage mercury rectifier
may be going bad. Break some new
ones in by running their filaments
for about an hour. Frequently "modulator tube trouble" will prove to
be not modulator trouble at all, but
a bad bias rectifier causing a lower
than normal bias on the modulator
grid. In this case, a new 5Ú4G, a
silicon, or a selenium rectifier will
frequently cure the ailment, and at
only the fraction of the cost of a
new modulator tube. Sometimes
good modulator tubes are scrapped,
and it is later learned that the trouble was in the bias supply. The bias
supply still has to be corrected before proper service is restored, and
a perfectly good modulator tube will
remain in the scrap box, or may
have been destroyed.
If you are familiar with the appearance of the modulator tube
plates in normal operation, the color
of the plates is the easiest way to
adjust modulator bias. Push-pull
modulators can be very easily balanced in this manner, and no equipment is required.
In a small station, where there is
not a great deal of equipment involved, tube replacement is often
best achieved by waiting until
trouble develops. (If the engineer
has a thorough knowledge of the
equipment!)
In some cases tube trouble can
show up as relay trouble. In the
Gates Studioette, the speaker muting and off the air light relays draw
their power from the console's rectifier tube. A weak rectifier can cause
the relays to be sluggish or inoperative.
In tape recorders, one can easily
tell when tubes need replacement.
When the gain starts falling off, you
can be pretty sure that you have
one or more tubes going weak. In
the P-6 Magnecords, this loss of gain
may be due to a bad copper oxide
rectifier which provides do heater
voltage on the input tubes. Observation of the input tubes will determine if this is the cause, or touching
them to see if they are as warm as
normal can suffice if the top of the
tube is blackened .
To be more precise, pull the machine out of the rack, put it on the
bench and check heater voltage with
a voltmeter. However, this is usually
unnecessary if the preliminary
checks outlined above are followed.
If the input tubes have adequate
heater voltage, the chances are that
one of the amplifier tubes is low on
emission, or the rectifier tube is
getting weak. Replace one at a time
until proper gain is restored. If replacing an old tube with a new one
does not help, replace the old one.
If you do all this and the tape machine amplifier gain is still low, get
out your diagram and voltmeter and
get to work.
In a tape machine that fails to
erase completely, the trouble is
usually a weak erase oscillator tube.
If a lot of hash is present in a recorded tape, you may have trouble
with a leaky capacitor in the erase
oscillator circuit. If it doesn't erase
at all, there is a good likelihood that
the erase oscillator tube is burned
out.
PROFESSIONAL STEREO TONE ARM
THAT "THINKS" FOR ITSELF
...designed for people who sometimes don't
A
One moving part, one precision bearing. Nothing delicate
to add to your maintenance worries.
Change cartridge in seconds. Pre -loaded slide assembly
automatically adjusts for lateral and vertical balance,
cartridge overhang and output.
Viscous damping eliminates audio frequency vibrations,
yet offers no resistance to groove motion.
GRAY 208-S
$49.50
write on company letterhead
for complete technical inforand
mation,
specifications
application data.
GRAY
RESEARCH AND DEVELOPMENT CO. INC.
Box 12, Elmwood, Conn.
Plant: North Mountain Road,
Newington, Conn.
BROADCAST ENGINEERING
28
www.americanradiohistory.com
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7425-7750
7750-8100
\1
Sylvania
Type
SK -220F,
SK -220E,
SK -220G,
SK -220D,
SK -220C,
SK -220B,
SK -220A,
222F
222E
222G
222D
222C
222B
222A
SK -220Z, 222Z
Frequency
(me)
Sylvania
Type
5250-5560
5860-6160
5985-6285
6285-6585
6505-6705
6705-7005
6955-7255
7255-7555
7550-7850
SK -221H
SK -221K
SK -221F
SK -221E
SK -221G
SK -221D
SK -221C
SK -221B
SK -221A
Available at O.E.M. prices in quantities of 1-99
from your Sylvania Industrial Tube Distributor
GENERAL TELEPHONE gELECTRON/CS CE^I
August, 1962
29
PROFESSIONAL
STANDARD OF
THE BROADCASTING
INDUSTRY
t
vgnecord
...
Proven by years
of reliable service the
world over.
128 STEREO
The professional
standard. 71 and
15 ips. Superior
performance
in all areas.
148 STEREO
The Olympian
...
champion of
recorders. 33/4 and
71/2 ips. 4 -track play
and record.
THE PT
6
The rugged, reliable
"Workhorse" of the
broadcast industry.
THE P 75
"The Editor"
includes all of the
capabilities of the PT
6 plus extended
performance and
...
utility.
THE M 90
"Mighty" in all
performance
characteristics.
Magnecord's finest
tape instrument.
Magnecord sets the standard
for Performance, Quality and
Reliability in the professional
sound and broadcast industry.
WRITE TODAY FOR
MORE INFORMATION
,..I
"
.
1k(11_,
,
..
_
MAGNECORD SALES DEPARTMENT
MIDWESTERN INSTRUMENTS
P. O. BOX
7509
TULSA 35, OKLAHOMA
World's Tallest Structure
Completed in Georgia
Television programs of WTVM
and WRBL-TV, Columbus, Ga., are
now being transmitted from antennas located almost a third of a
mile high, signaling completion of
a mammoth tower engineering project and said to mark the Georgia Alabama border as the site of the
tallest man-made structure in the
world.
Construction of the tower, which
supports an RCA Channel 3, six section super turnstile antenna and
an RCA Channel 9, Mark II super
gain antenna, was completed ahead
of schedule in less than two months
and without loss of air time for
either station. The work consisted
of extending the original 1,260 -ft.
tower and antenna structure erected in 1960. Weighing approximately
215 tons, the triangular structure
employs tubular materials for simplicity, low wand loading and greater
structural strength, and utilizes over
six miles of Bethlehem guy strand
cable.
Gates Transmitters For
USIA Broadcast System
Gates Radio Co., Quincy, Ill., reports the shipment of four 50 -kilowatt transmitters to be used in a
new U. S. Information Agency
transportable broadcast system.
Meeting USIA requirements for
a fast reaction type system, the
portable transmitting plants will be
flown to areas throughout the world
and operations quickly established
for relaying broadcasts from the
Voice of America.
Three New Appointments
Announced by Ampex
Ampex Corp., Redwood City,
Calif., has announced the appointment of three new manufacturer's
representatives to handle sales of
professional and consumer audio
equipment and magnetic tape in the
east and midwest.
Appointed were: Herb W. Knaggs
Co., Belleville, Ill.; Stinson-Platt
Co., Narberth, Pa.; and R. W.
Mitscher Co., Inc., Buffalo, N Y.
Knaggs represents Ampex in Nebraska, Iowa, Missouri, northern
Kansas and southern Illinois; Stinson - Platt in Pennsylvania and
southern New Jersey; and R. W.
Mitscher in New York State.
Reports Increase in Use
Of TV Tape Recorders
The number of television tape recorders in use in the United States
increased by 15 per cent during the
nine-month period ended June 1,
the RCA Broadcast and Communications Products division reported
recently.
The gain, which brings to 861 the
total number of recorders used for
broadcasting, closed circuit systems
and other purposes, was disclosed
in a division study of the TV tape
recording equipment market. An
additional 450 recorders of U. S.
manufacture are in use outside the
country. The RCA survey showed
a steady growth rate in all domestic user categories, with commercial
broadcasting stations leading with
a net gain of 49 units for the period.
Networks and educational TV stations also increased the number of
recorders in operation.
Vitro Moves Washington
Branch to Silver Spring
The Washington branch of Vitro
Engineering Co. has moved to new
quarters in the Yeager Bldg., 721
Ellsworth Drive, Silver Spring, Md.,
according to an announcement by
Joseph Mazia, branch manager.
In this move, Vitro Engineering
now joins two other divisions of
Vitro Corp. of America-Vitro Electronics and Vitro Laboratories-in
operations in Silver Spring. Total
company employment in the area
exceeds 2,400. Vitro Engineering
established the Washington branch
in 1956, to serve government and
industry in standards engineering,
technical documentation and manual preparation, and engineering
management.
BROADCAST ENGINEERING
30
www.americanradiohistory.com
1
GEORGE R. TOWNSEND, VICE PRES.
/ ENGINEERING,
STATION WWLP, SPRINGFIELD, MASS., SAYS:
"Few Engineers
Will Dispute Conrac's
their monitors are as irouble-free as any
precision equipment work with."
I
CONRAC MONITORS ARE DISTRIBUTED BY RCA, AMPEX,
GENERAL ELECTRIC, AND VISUAL ELECTRONICS.
CCONRAC) 01 VISION
GL END ORA, CALIFORNIA
GIANNINI CONTROLS CORPORATION
telephone: AREA CODE 213-335-0541
New York: 6902 Empire State Bldg, New York
August, 1962
1,
Tel: AREA CODE 212-594-1160
3
Induetlte NeJU4
Seventh Annual New York
High Fidelity Music Show
The seventh annual New York
High Fidelity Music Show, the
leading annual event of the hi-fi
industry, will be held at the N. Y.
Trade Show Bldg., October 2-6. The
live demonstration public exposition
will be the largest in history, ac-
"We at WRTA feel that SPOTMASTER
is the most versatile instrument
introduced
to broadcasting since the advent of tape."
Louis Murray,
WRTA, Altoona
Wherever you find a SPOTMASTER unit in use-the opinions of
we
broadcasters are the same: "Tighter cueing and better sound
are very pleased." (KOGO, San Diego) "No more noisy playbacks
or jumping grooves. We have not bought a single acetate blank disc
since installing your machines in July, 1960." (WFBR, Baltimore)
"We have improved our production immensely," (KING, Seattle)
frankly, I don't know how we ever got along without this equipment." (WGTC, Greenville, N. C.) SPOTMAS 1 ER, is engineered
...
"...
for compactness, efficiency, reliability and low maintenance. It is the
most field-tested and field-proven cartridge equipment manufactured anywhere. We would like to tell you more about the SPOTMASTER
Cartridge Recorders. Call, write or wire today.
Your Key to Pushbutton Broadcasting
ELECTRONICS INC.
BROADCAST
Brookville Road, SilveESpring,Maryland,Dial 1U8-4983
8800
SOLD NATIONALLY BY: Visual Electronics Corp., 356 West 40th Street,
N.Y., N.Y., Richard H. Ullman, Inc., 1271 Ave. of the Americas, N.Y., N.Y.,
CANADA-Northern Electric Co., Ltd., 250 Sidney St., Belleville, Ontario.,
AUSTRALIA-Simon Gray Pty., Ltd., 28 Elizabeth St., Melbourne, C.1
32
cording to Raymond V. Pepe, president of the Institute of High Fidelity, Inc., the sponsoring association.
It will occupy five entire floors and
house several million dollars in high
fidelity and stereo components. The
vast majority of manufacturers' exhibits will consist of new products
from the U. S. and abroad.
Record attendance is predicted
by the Institute. Last year more
than 30,000 persons viewed 130 exhibits of manufacturers at the show.
The Institute credits the show with
helping substantially to stimulate
industry sales in 1961 to an unprecedented high.
The Institute reported that there
are about 1,100 FM stations now
broadcasting in this country, and
that FM -stereo broadcasting, which
began only last June, has made outstanding strides. More than 40 per
cent of the American population,
some 71,000,000 persons, are now
within hearing range of the 100 FM
stations broadcasting stereo regularly.
Television Programs
Relayed 305 Miles
Towering peaks in the rugged
southwest mountain country provide the natural relay sites for an
intricate microwave system that
picks television signals out of the
air 70 miles from a transmitter and
flashes them 305 miles to KOATTV in Albuquerque, N. M. As it
hops along the route of unattended
microwave repeater stations, the
TV signal is guarded by automatic
fault reporting and standby switching equipment which insures continuity of operation in the event of
a failure at any point. These features make the system "the most
dependable and complex microwave
relay ever installed by an individual
television station," according to
C. H. Colledge, division vice -presi -
BROADCAST ENGINEERING
dent and general manager, RCA
Broadcast and Communications
Products division, which designed
and built the system in cooperation
with the KOAT-TV engineering department.
Atop 7,850 -ft. Pinal Peak, the
first relay station receives an off the -air signal from KTVK, ABC
network affiliate in Phoenix. Instantaneously it is beamed to
Greens Peak, 10,200 ft. high, and
thence through two other stations
to Sandia Crest, site of KOATTV's transmitter. A final microwave relay there carries the network signal to the studio. The
Greens Peak location, which is 140
BAUER TRANSMITTERS
Provide Top Performance With t4,'nimum Maintenance
miles from Phoenix, also serves as
an alternate off -the-air pickup point
in the event the Pinal Peak station
becomes inoperative. If this should
happen the signal failure would
automatically trigger the alternate
receiving equipment into operation
and the program would continue
without a break.
First City -Wide
1,000
WATT FM
Ste eo-Ready.
Simple design.
Radio/TV Antenna
Tierra Verde, a city for 25,000
people being completed in the Gulf
of Mexico off the coast of St.
Petersburg, Fla., will have only one
TV antenna.
Zoned for 50 per cent residential
and 50 per cent commercial building, one master TV antenna will
boost the signal and transmit it to
each building site by underground
coaxial cable, thus ensuring studio
reception over the entire 2,000-acre
area. The cable will also transmit
am/fm radio, closed circuit television, and a 24 hour a day musical
program. This is the first city-wide
use anywhere of a single antenna
for public TV/radio reception.
Built-in load. Factory assembled
Davis Appointed Ampex
Sales and Service Manager
5,000/1,000
Thomas E. Davis has been appointed manager of sales and service for Ampex Corp., Redwood City,
Calif., it has been announced by
C. Gus Grant. vice-president.
In his new post, Davis is responsible for nationwide sales and service activities which are carried out
through Ampex regional sales personnel, representatives, distributors
and dealers. He succeeds John Jipp,
formerly vice-president and manager of sales and service, resigned.
or Lit Form.
10,000 WATT
Ceramic tubes in P1
bility. Lowest power grau rpion-high efficiency
design. Only 9 tube:
t'pe;.
WATT AM
FA
The
rectifier system (standard in all Bauer transmitters). Fcot-Eroaf
circuit protection with tally-light/overload relay system. Lrw
in
c
apa-
ani modern
1,000/250 WATT
6,100 watt output capability. Continuous metering. Sold 'state
po ver
AM
Modulator. 12,500 watt output
a
AM
famous Model 707. Laader
the field. Easiest to Buy.
Easiest to Operate. Factory as-
sembled or Kit Farm.
consumption-economical to operate.
WRITE FOR THE COMPLETE ENGiEERING STORY TODAY!
ELECTRONICS
CORPORATION
1663 Industrial Road, San Carlos, Califoriia
August, 1962
/.rea Code 415 591-9466
33
www.americanradiohistory.com
used to concentrate the signals in
areas where most of Detroit's
schools are located. The effective
radiated power of the translator is
Induetiuj Newa
Yeager to Newly -Created
Post at Altec Lansing
Altec Lansing Corp., a subsidiary
of Ling-Temco-Vought, Inc., Anaheim, Calif., has announced the
promotion of William E. Yeager to
the newly -created post of engineering information manager.
For the past six years Yeager
served in the field as regional sales
manager covering the mid -Atlantic
states for Altec.
UHF TV Repeater to Carry
Airborne Educational Programs
A 100 -watt UHF TV translator
will permit regular reception in Detroit schools and homes of the programs broadcast from the flying
schoolhouse of the Midwest Program on Educational Television.
The airborne programs originate
from a DC -6B circling 23,000 ft.
above Montpelier, Ind., and are received in parts of Illinois, Ohio,
Michigan, Wisconsin, Kentucky and
Indiana.
The translater station, which is
being supplied by Adler Electronics,
Inc., New Rochelle, N. Y., will
broadcast from atop the 285 -ft.
Maccabees Bldg. in downtown Detroit. Its operation will be similar
to that of the 400 UHF translators
which rebroadcast standard commercial and educational TV into
fringe and isolated areas. The UHF
signals from the 165 -mile distant
DC -6B will be picked up off the air
by the repeater, converted to a new
UHF channel to prevent interference, and beamed over the Motor
City. A directional antenna will be
Save
1,380 watts.
James Sims to Represent
Visual in Southeast
The appointment of James Sims
to the technical sales staff of Visual
Electronics Corp., New York, N. Y.,
has been announced by James B.
Tharpe, president of the firm. Sims
will supervise the company's broadcast account -servicing in the states
of Alabama, Florida and Georgia,
and will set up regional headquarters in Miami, with an operative
branch in Atlanta.
Sims brings to Visual an extensive sales and engineering background in the broadcast field, with
particular emphasis on TV station
equipment planning and operation.
Recently, as director of engineering
of WAPA-TV (San Juan) , in addition to his other duties, he engineered and installed the first broadcast microwave multi -hop system
to be used in Puerto Rico.
United States Exhibit
Shows ETV to Africans
Educational TV and its potential
impact in underdeveloped areas was
demonstrated to over 110,000 Africans recently by Blonder-Tongue
Laboratories, Inc., Newark, N. J.
The display, a model electronic
teaching lab, was one of the major
highlights at the official U. S. exhibit at the Third Central African
Trade Fair held in Bulawayo,
Southern Rhodesia.
The teaching lab, a CCTV system with cameras, audio, monitor,
lighting and other devices, demon-
strated the conversion of a classroom and laboratory into a fully equipped studio. To dramatize the
exhibit, thousands of visitors to the
American Pavilion were shown a
live demonstration in the studioclassroom. Simultaneously, visitors
were able to view and hear the
teaching session on a studio TV
monitor. Head phones were also
provided at the display to give an
on -the -spot explanation of ETV.
GEL
Appoints New
Sales Representative
Howard T Dempsey has been
appointed broadcast equipment
sales representative covering Colorado, Wyoming, New Mexico, Arizona and Utah, it has been announced by General Electronic Laboratories, Inc., Cambridge, Mass.
Equipment necessary for complete broadcast installations will be
handled by Dempsey from his office in Denver, Colo.
Build Greek
Phone -TV Network
Receipt of a contract to provide
To
a new telephone and television network covering most of Greece has
been announced by a British, subsidiary of International Telephone
& Telegraph Corp., Standard Telephones & Cables Ltd. The network,
a multicircuit, microwave radio system, will be built for the Hellenic
Telecommunications Organization,
S. A. (O.T.E.) , of Athens
The system's total route length
of over 500 miles will be covered in
17 radio hops, half of which are
over-water paths. The equipment to
be supplied will initially provide
two working broadband radio channels and one standby channel. Each
of these radio channels can carry
30%ono-Track
Stereo Music on Tape!
Empty
3
in. Plastic Reels le ea.I
*jTWING
BARGAIN PRICES! Send for our FREE Tape
Recorder/Blank/Prerecorded Tape Catalog #B-3
SAXITONE RECORDING TAPE
Oxide guaranteed not to rub off or squeak-or money
back. Compare oura with other "Bargain" tape. You'll
find ft's more than just "price" when you deal with
us. We are original pioneers In the tape recorder busanese and our reputation means everything to us.
.73
600' Acetate (plaatic), 5"
600' MYLAR 5" reel
.9S
.99
900' MYLAR (Polyester). 5"
1.15
1200' MYLAR, Vs mil. 5" reel
NORELCO SPEAKER
Famous AD3800M, twin
cone 8"(75-19,000 cycles)
discontinued model, former list 16.00, usual net
9.90 going at 4.99 plus
postage. (2 for 9.00).
Other Norelco speaker
sizes at bargain prices.
Send for SPEAKER SPECIFICATION SHEET.
1.19
Acetate (Plastic). 7"
1.98
MYLAR. 11/2 mil (Strong)
1.79
Acetate plastiC). 7"
1.99
MYLAR, 1 mil. thick. 7"
2.99
MYLAR, unteneilixed. 7"
2.99
MYLAR, teneilised, 7"
Studios, Large User» Even Lower. PLUS POSTAGE.
Allio-Scotch, Irish. Audio, Reeves. Ampex and Suches-Tareisa magnetic tapes. mikes,
audiodiscs. needles, etc. We'll surprise you with our quotationst
1200'
1200'
1800'
1800'
2400'
2400'
SAXITONE TAPE SALES
(Division of Commissioned Electronics Company. Inc
WASIII
1776 COLUMBIA ROAD
34
)
TV ANTENNAS
CHANNELS 2-13
Write for Sales Catalog
JAMPRO ANTENNA CO.
7500 - 14th Avenue
Sacramento 20, California
9. D.C.
BROADCAST
ENGINEERING
960 high -quality telephone circuits
or a television channel. The system
has an ultimate capacity of six
radio channels. In addition, the
routes are designed to be linked up
with the TV networks of neighboring countries and with the Eurovision system.
STC will supervise the installation, which will be carried out by
engineers of the O.T.E. Delivery
will commence in the autumn of
1962. Equipment, of a type called
space -diversity, will be used to
minimize signal fading It will operate in the 4,000-megacycle frequency band.
Stainless Appointment
To J. C. Rodriguez
Stainless, Inc., North Wales, Pa.,
has announced the appointment of
J. C. Rodriguez as broadcast sales
engineer. He will be stationed at
the company's headquarters in
North Wales, and will handle broadcast tower sales and special assignments here and with the firm's subsidiary, Walcan, Ltd., Ontario, Canada, according to Henry J. Guzewicz, Stainless president.
NEW FAIRCHILD CONAX
ELIMINATES
PRE-EMPHASIS
PROBLEMS
AUTOMATICALLY!
Mop
CONAX
will produce increased signal levels in
recording and FM broadcast
CONAX will reduce distortion in tape recording
and tape duplication
CONAX will minimize tracing distortion
CONAX has been engineered by FAIRCHILD to
cope with the problem of distortion produced in
recording and broadcasting by excessive, instantaneous high frequency peaks. The CONAX "previews" program material in emphasized form for
efficient high frequency control. The device is
based on the integrating properties of the human
dar. The CONAX action is inaudible and instantaneous
1/40,000ths of a second. CONAX efficiently eliminates problems of overload from loud
cymbals, muted trumpets, bells, and the everpresent sibilant singers without quality degradation.
Model 602
Stereo $495.
Mono $330.
600
Book revi&t
ABC's of Mobile Radio
Catalog No. AMR -I. Published by
Howard W. Sams & Co., Inc., Indianapolis 6, Ind. 96 pages. Price $1.95.
"ABC's of Mobile Radio," by
Richard Martin, presents a basic
introduction to two - way radio,
where it is used, and how it works.
It completely describes the use and
operation of transmitters, receivers,
power supplies, and antennas.
Using practical, down - to - earth
language, the book will be useful for
two-way radio owners, operators,
and service technicians.
-
FAIRCHILD
RECORDING EQUIPMENT CORPORATION
10-40 45th Ave., Long Island City 1, N.Y.
August, 1962
Electronic Musical Instruments
Handbook
Catalog No. EMI -I. Published by Howard W. Sams & Co., Inc., Indianapolis
6, Ind. 128 pages. Price: $2.50.
In "Electronic Musical Instrument Handbook," the first complete
book on the subject, Norman H.
Crowhurst fully explores the development of electronic music. This
new realm of sound production is
explained in such a manner that
musicians, hobbyists, and technicians will find the content both useful and informative.
Tube Substitution Handbook
Vol. 4, Catalog No. TUB -4. Published
by Howard W. Sams & Co., Inc., Indianapolis
6,
Ind.
112
pages.
Price:
$1.50.
The directory of receiving tubes
has been expanded to 1,758 types,
with over 3,000 substitutions. Other
sections list 242 industrial and 622
V'T'1
B/E Classified Ads
Get Results!
[email protected]
produces color and monochrome
Remotes
studio programs with the
Super Universal Zoomar Lens
...
We have used the Super Universal lens
successfully on many kinds of programs,
including color and black and white
remotes, different types of studio programs, and find it would be almost
impossible to acomplish certain
effects without this type lens.
Very truly yours,
-
-
foreign substitutes for American receiving tubes, and 530 American
receiving-tube substitutions for foreign types. The picture -tube section
shows 508 types, with recommendations for 1,916 direct substitutions.
A brand-new section on subminiature tubes lists 250 substitutes for
285 types.
indse
. Riddle
Chief Engineer
Call for
a
demonstration on your cameras
JACK A. PEGLER o
BILL PEGLER
TELEVISION ZOOMAR COMPANY
500 Fifth Avenue, New York 36, New York
-
BRyant 9-5835
35
PitxrdiuL Neure
MINIATURIZED 3D -TV
STEREO -CAPTOR
NO-BREAK GENERATOR UNITS
MULTIPLEX GENERATOR
A new FM multiplex generator that can
be used to align receivers or adapters has
been announced by Hickok Electrical Instrument Co., 10514 Dupont Ave., Cleveland 8,
Ohio.
According to the manufacturer, the model
725 generates complete FM multiplex signal
to FCC specifications. The composite output
consists of (1) L plus R generated by two
stable self-contained oscillators 400 cps and
1200 cps, (2) L -R produced by a double balanced modulator. The output of the
modulator contains the L -R side bands of
the suppressed 38 KC subcurnier, and (3)
a 19KC pilot carrier used to synchronize
the demodulator of the stereo receiver or
adapter being tested or aligned.
The RF output is tuneable over the FM
band and modulated with the composite
stereo signal. The output is variable from
2-1000 microvolts. By putting RF input into
antenna terminals, the technician can determine whether the FM receiver band pass is
adequate for FM multiplex stereo reception.
The generator can be externally modulated
by an external signal source such as a
stereo mike, tape player or record player
(one volt p-p min.).
Automatic Power, Inc., 205 Hutcheson St.,
Houston, Tex., has announced the availability of the no-break generator units which
are designed to provide 109 per cent continuous power to critical loads when commercial power fails. The units are said to
supply constant stand-by power in any
weather, in any terrain, for any emergency.
The unit is comprised of a Nordberg
Power Chief engine, coupled to a staticallyexcited motor generator through a heavyduty magnetic clutch. The engine flywheel
rotates with the motor generator rotor and
is mounted on tapered roller bearings, supported by the engine shaft. Under normal
conditions, electrical power is supplied to
the critical load by the generator which is
driven by an electric motor. The motor
draws electrical energy from the commercial power. In the event of commercial
power failure or a drop in voltage, the
motor is automatically disconnected from
the line, energizing the magnetic clutch
which connects the flywheel to the engine
crankshaft. Inertia stored in the flywheel
continues to drive the generator and brings
the diesel engine up to operating speed.
When commercial power is restored, the
electric motor is again energized and the
engine is shut down in the reverse secuence. The sets are available in 5 -kilowatt
to 25 -kilowatt capacities.
r ------------
A stereo -captor. which will optically convert any closed-circuit television to a 3D
picture with no electronic modification, has
been miniaturized to an 11 -oz. package by
Stereotronics Corp., 1717 N. Highland Ave.,
Los Angeles 28, Calif.
The system consists of stereo-captor model
5502, which replaces the lens on any industrial TV camera; a stereo screen to replace
the glass plate in the receiving monitor;
and stereo glasses for group viewing, or a
stereo -hood for individual viewing without
glasses.
The unit features quick installation and
conversion from 2D to 3D; fidelity of depth
perception; and simplicity of design and
operation. The miniature package can be
used on underwater and space vehicles
where size and weight are limited, and
within environmental housings in radioactive and explosive areas. Wide-angle viewing is provided by means of integral dual
12.5 mm focal length lenses. Convergence
control adjusts toe -in from 12 inches to
infinity.
-
For Convenient,
Low -Cost Remote Control
SPECIFY
NEW HEAT EXCHANGERS
Please send me, at no obligation, a suggested Remote
Model No.
Control Plan for my Transmitter, Make
Name
Station
Address
City
Title
State
GENERAL ELECTRON/C
LRBORRTOR/ES, /NC.
36
195 MASSACHUSETTS AVE., CAMBRIDGE 39, MASS.
------------uu---------1111
Barnstead Still & Sterilizer Co., 377 Zanesville Terr., Boston 31, Mass., has announced
the development of a new line of heat exchangers for heating purified water wherever it is required for washing and rinsing
operations. The unit may also be used for
cooling purified water. All interior surfaces
are coated with pure inert tin to prevent
metallic contamination of the purified water.
The heat exchangers are available in
capacities of from five to 3,000 gal. per
hour. Full automatic controls are included
for temperature regulation. The units may be
used singly or in series with distilled or
de -mineralized water purification equipment
where pre -heating is not possible.
BROADCAST ENGINEERING
I
Brochure RD1885 describes a transistor
tester which measures beta and leakage
from data included on a roll chart. Transistor manufacturer's specifications, or the
user's requirements can be the basis for
transistor testing.
The brochure includes technical specifications, simplified schematic diagrams, and
circuit descriptions of the beta and leakage
tests, the variable duty cycle pulsing sys
tem, and the variable power supplies.
.
1
General Industrial
smeeRag
manufacturers' pages and three directories.
The product directory lists over 3.000 products from 109,000 product sources, with
company names and addresses. The manufacturers directory lists the names, addresses, phone numbers, sales offices and
key personnel of 6,300 manufacturers. The
trade name directory has 6,800 trade names
with their respective manufacturers.
47.
GfNERAIINDUSTRIAL CO.
n.;<., m.
iO,yx.«n
IMAGE TUBE RESOLUTION CHART
The square -wave aperture response curve
image tubes and systems can be obtained
simply with a new resolution chart available from Westinghouse Electronic Tube
Div., Box 284, Elmira, N. Y., and was developed for resolving power of new image
tubes.
In use, the chart provides a resolution
image which is picked up by a camera
of
SPA RTA-MATIC
-®
300P
-
li
tube, and the resulting video signal is fed
into an oscilloscope set for a delayed sweep.
It is thereby possible to obtain the information required for a complete square -wave
aperture response curve with a single scope
presentation.
The chart consists of nine identical groups
of lines. Because of this arangement the
resolving power can be measured and compared at different locations on the target.
The 100 per cent contrast chart in an 8x10 inch transparency is available immediately.
Charts with other degrees of contrast are
available by special request.
ELECTRONIC ENGINEERS MASTER
The 1962-63 edition of EEM-Electronic Engineers Master, totalling 2,090 pages, has
been released. The publisher announced
that the edition is also available on microfilm that will accommodate 90 per cent of
all viewers now available on the market.
EEM is composed of a catalog section of
NEW TECHNICAL BROCHURE
Hickok Electrical Instrument Co., RD Instruments Div., 10514 Dupont Ave., Cleveland 8, Ohio, has announced the availability of a new eight -page, two-color technical brochure which desribes the model
1885 Dynamic beta power transistor tester.
,
.
®.
i.soi
CIRCULAR SLIDE RULE
Ganeral Industrial Co., 1'/88J Montrose
Ave., Chicago 13, Ill., is offs-ing a circular
slide rule for engineers and other plant and
office executives.
According to the manufacturer, operation
of the pocket-siza calculator is simple and
results accurate. Complete easy-to -follow instructions are included with each slide rule.
iiii
ir
gg440Eig [1I MAPMQD
coN Cl4QULDGN 4QM
1
SéAlkTA-MATIC
$450.00
The SPARTA-MATIC 300 series cartridge tape system
is receiving enthusiastic acclaim by broadcasters
everywhere! Offering outstanding improvements in
all areas, the SPARTA-MATIC 300P playback unit
and its companion 300R record amplifier, contain all
the features you have been waiting for:
Continuous Duty Rated
Compact, Modern, Functional Design
Laminated Tape Heads
Proven Reliability
Table Top, Custom or Rack Mounting (Rack Mounting Illustrated)
Improved Tone Burst Cueing
Plug in Relays and Modules
Solid State Design
All this and much more is yours with the new leader
SPARTA-MAT1C. Dependable quality that every broadcaster can afford.
The sophisticate of cartridge tape: the SPARTA-MATIC 300 series.
..
300R
-
$210.00
.
Call, Write or Wire Today for Guaranteed Satisfaction Offer.
SPA RTA
6430 FREEPORT BOULEVARD
August, 1962
ELECTRONIC CORPORATION
SACRAMENTO 22, CALIFORNIA
GA
1-2070
(
1
37
per cent with output voltages lmV to
1.5
V into 400 ohms.
MI)
NEW OPTICAL SYSTEM
A new dual lens system for vidicon TV
and 35mm data recording cameras has been
introduced by Zoomar, Inc., Glen Cove, Long
RACK -MOUNTED CARTRIDGE -TAPE
SYSTEM
The addition of the Spotmaster Rack
Mount series of playback and combination
recorder -playback units to its line of broadcast equipment has been announced by
Visual Electronics Corp., 356 W. 40th St.,
New York 18, N. Y. The units are designed
to provide pushbutton broadcasting for
AM/FM and TV broadcast operations.
Furnished with rack chassis slides ready
to mount in existing racks, each Rack Mount
slides in and out, exposing the head and
capstan for accessibility in cleaning and
routine maintenance of the cartridge deck.
Both the combination recorder and the playback are equipped with mounted handles.
Island, N. Y.
The new system is built around the
40-inch/F.8 Reflectar and an 8 -inch Achromat fixed focus F/8 lens. Features include
an optical switching device to permit instant
selection of lenses by remote control, with
a sun protector to safeguard the vidicon
tube. The Reflectar also is focused by remote control. A reticle projector comprising
light source, condensing system, reticle and
projection optic produces crisp measuring
pattern on the monitor screen. The azimuth
and elevation platform is designed for boresighting alignment within 2=11/2° azimuth
and elevation, and micrometric adjustment,
two seconds of arc. The entire system,
which is weatherproof, measures 24 inches
long, 12 inches wide and 15 inches high,
and weighs approximately 35 lb. without
camera. The unit is normally supplied with
a vidicon TV camera, but is also available
for 35 mm data recording cameras.
000
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.
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.
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*
VHF FREQUENCY STANDARD
A portable, 16-ib. VHF frequency standard,
designed to provide an accurate check on
operating frequencies of mobile transmitters
and receivers, has been introduced by
Wayne Kerr Corp., 1633 Race St., Philadelphia 3, Pa.
The FS100 has a maximum of 48 discrete
frequencies in the range from 7.5 megacycles to 175 megacycles. A crystal-controlled oscillator, frequency multipliers, a
wide -band detector and all rectifying and
smoothing circuits for operation from alternating current supplies of 90 to 140 volts
and 180 to 250 volts are contained within
the instrument. Up to six thermostatically controlled plug-in ovens, each capable of
housing two crystals, can be fitted. A
12 -position switch connects one of these
crystals into an aperiodic Colpitt's oscillator
circuit. The 3rd, 9th and 18th harmonics are
developed by the frequency multipliers.
Frequency stability and accuracy is ±0.0003
38
f,w.,+.+
.
e
i
;
__--
eee:
000,
SILICON RECTIFIER REPLACEMENTS
FOR ELECTRON TUBES
Columbus Electronics Corp., 1000 Saw
Mill River Rd., Yonkers, N. Y., has announced the release of more than 60 types
of silicon rectifiers designed to permit direct
plug-in replacement of vacuum or gas -type
rectifier tubes.
Available in ratings to 40,000 volts PIV
and
2.5 amperes, the CP series is said to
permit the replacement of the tube types
5U4, 6X4, 3B28, 866, 8008 and many others.
NEW BOOM MICROPHONE
Collins Farley Corp., 606 W. Washington
Blvd., Venice, Calif., is offering the new
type M boom microphone which, whea
added to the series 95 headset, makes an
integrated microphone -receiver unit offering
numerous advantages to users requiring the
transmit -receive functions.
The microphone is housed in an attractive plastic case on an anodized aluminum
boom. Microphone and boom may be swung
away from the speaking position to an
over -the-head position, moving it out of the
way when not in use.
TELECHROME VIDEO
TEST EQUIPMENT
The first models in a new line of transistorized video test equipment for both color
and monochrome TV systems has been announced by Telemet Co., 185 Dixon Ave.,
Amityville, Long Island, N. Y.
Shown (top to bottom) are, model 3501 -Al,
multiburst generator, model 3502 -Al stair step generator and model 3505 -Al sinesquared pulse -window generator. All are
completely transistorized and feature a new
lightweight, compact design. The units
measure 13/4 inches high and are designed
to fit the standard 19 -inch rack. They have
individually regulated and fused power supplies and are said to perform reliably at
ambient temperatures to 60 -deg. C (140deg. F).
Each generator provides two simultaneous
output signals-a composite video signal
and a vertical interval test (VIT) signal.
The VIT signal may be added during the
vertical blanking interval of a program signal, while the composite video signal is
available as a standard video test signal
for distribution to the studio system.
NEW WAVEFORM MONITOR FOR
CLOSED-CIRCUIT TV STUDIOS
A new waveform monitor, model WFM-5,
for closed-circuit TV system studios, has
been announced by Blonder-Tongue Laboratories, Inc., Newark 2, N. J. The new unit,
which is capable of monitoring a video
signal, is designed for professional systems
cniy, those using E.I.A. standards.
The monitor features a 5 -inch oscilloscope
screen on which are displayed either two
horizontal lines or two vertical fields for the
operator. It has a built-in calibrator and
power supply, and requires vertical and
horizontal drive pulses. The unit is designed
for a 19 -inch rack mount.
BROADCAST ENGINEERING
NEW SECO SIGNAL FILTER
A new electronic noise eliminator and
MINIATURE ELAPSED TIME METER
Curtis Instruments, Inc., 45 Kisco Ave.,
Mount Kisco, N. Y., has announced a new
miniature elapsed time meter, resettable to
zero in the field cnd developed for applications including time usage studies on studio
transmitter and test equipment.
The meter utilizes the Curtis meter element based on electro -chemical transfer of
mercury in a sealed system. A precise constant current plates mercury across a gap at
an exact rate, and movement of the gap is
directly proportional to time.
Standard models cased in a miniature,
high -strength housing are available for timing up to 10,000 hours on a 1 -inch scale.
Accuracy is within 3 per cent at voltages
from 100 to 140 ac, and frequencies from
50 to 400 cps.
The Indachron model 515 R uses an integral rectifying and regulating circuit. During the normal timing cycle it is installed
directly across the ac line voltage. For reset,
the reset connections are attached to a
5 milliampere dc source and the indicating
gap runs back down the scale at the rate
of 1/2 -inch an hour. Upon completion of rezeroing, the meter will time an additional
cycle. Standard current sources for reset can
controllable squelch called the Signal Filter
has been developed by Seco Electronics,
Inc., 1201 S. Clover Drive, Minneapolis 20,
Minn. The unit measures 1% x 21/2 x 41/4
inches.
A dual high -mu triode and dual diode
are incorporated in an inverter circuit which
electronically clips noise pulses out of the
signal. It is said to eliminate ignition equipment interference, steep wave front hash
and background noises, as well as the need
for suppression equipment on automotive
and marine engines. The noise eliminator
features extra ruggedness through the use
of an encapsulated packaged electronic
circuit assembly.
The signal filter adapts to most Citizens
Band transceivers using tubes, and may be
hooked up to any AM superheterodyne receiver with six or 12 volts ac or dc and
150 volts B power supply, mobile or base
stations.
NEW MINIPRINT KITS
MiniPrint Electronics Co., Inc., 256 First
Ave., Cannel, Ind., has announced four new
kits for engineers, technicians, amateurs and
hobbyists who wish to make their own
printed circuits. Utilizing the latest techniques, the kits are said to allow the user
to make electronic printed circuit boards of
professional quality at a cost range to
satisfy both the simplest and most sophis-
ticated needs.
The material supplied in each kit is XXXP
phenolic board. It can also be supplied with
epoxy glass board.
LOOKING
FOR
CONNECTORS ?
Turn to section 2100
111'®mai
You'll find the catalog data
of these manufacturers:
Amphenol
Associated Engineering
Burndy
Augat
Barnes Development
ContinenCinch Mfg.
Cannon Electric
E -Z -Hook
tal Connector Dage Electric
GC Electronics
Test Prods.
Elco
Mac Panel
Grayhill
E. F. Johnson Co.
North
Co.
Microdot
Mueller Electric
Pomona
Electric
Physical Sciences
Rye
Security
Sound
Electronics
H.
Herman Smith
Devices Lab.
Thomas & Betts Co.
U. S.
Switchcraft
Virginia
Components
Viking Industries
Electronics.
eem ELECTRONIC ENGINEERS MASTER
60 Madison Avenue
be provided.
Hempstead, N.
for your tower
requirementsc
Y.
ROHN
SYSTEMS
complete tower
erection service
that has these
special advantages:
A
ALL TRANSISTOR VIDEO MODULES
Riker Industries, Inc., Halesite, N. Y., has
developed a new line of video equipment
NEW DC -AC INVERTER
SunAir Electronics, Inc., 3101 Southwest
3rd Ave,. Fort Lauderdale, Fla., has an-
nounced the development of a new design
for a dc-ac inverter, said to be capable of
delivering greater power output from the
energy source than the conventional power
supplies.
The new power pack delivers 117 volts
ac at 2.5 amperes and 60 cycles per second
from a 12 -volt battery source. Heat radiation fins on opposite sides of the chassis
are designed to permit cooler operation of
the transistors.
The inverter is normally furnished with
four transistors. If voltage regulation to tight
tolerances is required, a regulator pace
an be provided. Power supplies can also
be engineered to provide specific voltage
regulation; rectification from ac to dc with
specified ripple factors. The input voltage
range may be from 6 to 32 volts dc; ambient
temperature range from minus 35 deg. to
plus 55 deg. Centigrade. Voltage output can
be up to 300 volt/amperes with a mean
efficiency of 87 per cent.
August, 1962
for TV broadcast, microwave and radar
which is 100 per cent transistorized and
comes in modules.
Each video test waveform is generated
DEPENDABILITY
RELIABILITY
by a single module, and each module operates independently. As many as 10 modules
plug into the rack or portable carrying case
instantly and without tools. The user may
purchase basic waveforms and add any
others as desired. Additional advantages
include compactness -10 module set occupies 31/2 x 19 x 17 inches, weighs 25 lb,;
minimum heat and power-10 modules require 30W at 117V; amplitude stability
better than 1 per cent from 0-50 deg. C; not
affected by distortion, amplitude, or rise
time of incoming drive pulses; and for ease
of repair, each module consists of replaceable circuit cards for instant service.
COMPLETE
ENGINEERING
t/ COAST
TO COAST
SERVICE
Be sure to obtain price quotations and engineering assistance for your complete tower
needs from America's foremost
tower erection service.
TELEVISION ENGINEER
NEED GOOD RIGHT HAND MAN. MUST BE EXPERIENIED AND COMPETENT IN TROUBLE -SHOOTING
RCA STUDIO, TRANSMITTER AND MICROWAVE
EQUIPMENT. GOOD OPPORTUNITY FOR RIGHT MAN.
JERRY
KRIS -TV
E.
Box 840
SMITH, W5TFV
Corpus Christi, Texas
ROHN SYSTEMS, INC.
6718 W. Plank Road
Peoria, Illinois
39
Pduet Neure
SCA model S, with a capacity of 225 ft.
designed for broad-
of tape, is specifically
casting, message repeaters, audio and visual
display devices and language equipment.
The SCA model L, with a capacity of 1,690
ft., is designed for background music, data
retrieval, or where longer tape lengths are
required.
The new design pressure pad assembly
is said to increase frequency response and
reduce head wear to insure a uniform high
quality of reproduction regardless of the
number of cartridge insertions.
CONTINUOUS TAPE CARTRIDGES
Sound Corp. of America, 9162 Brookville
Rd., Silver Spring, Md., has introduced two
new models of continuous tape cartridges
that are said to be compatible with all
current models of continuous cartridge playback equipment.
Adufctieeie' Index
TELEVISION STORAGE
TUBE SYSTEM
Image Instruments, Inc., 2300 Washington
St., Newton 62, Mass., has introduced the
new model 207 Electrostore recording stor-
age tube system. Operating at standard
E.I.A. television scanning rates, the unit is
said to store and instantly read out for
continuous display a single television frame.
It differs from the model 206 Electrostore
in that it does not include a sync pulse
separator, and it requires line drive, frame
drive and composite blank pulses.
Resolution of 1,000 television lines across
the diameter and a gray scale fidelity of
five to six shades are achieved by the
Raytheon QK 685 Electrostatic storage tube
in the model 207. Read-out is non-destructive and the stored picture may be repeatedly displayed on a TV monitor for 10 minutes or more, the manufacturer states.
S
pioeee
iem
SYNCHRONOUS MAGNETIC FILM
RECORDER/REPRODUCER
MAGNETIC TAPE RECORDERS
NEW-THE portable MINITAPE synchronous 13 lb., battery operated
magnetic tape recorder for field recording.
THE STANCIL-HOFFMAN CORP.
845 N. Highland, Hollywood 38, Calif.
HO 4.7461
B
Dept.
VIR N. JAMES
Specialty
Directional Antennas
DExter 3.5562
232 S. JASMINE
DENVER 22. COLORADO
Member AFCCE
CONSULTING RADIO ENGINEERS
Specializing in AM -FM-TV Applications
and measurements.
934-5 Munsey Building
N.W.
Washington 4,
DI 7-2330
Established 1954
40
33
17
32
Conrac Div.,
Giannini Controls Corp.
Electro -Voice, Inc.
Electronic Engineers
Master Catalog
31
IBC
39
Fairchild Recording
Equipment Corp.
35
General Electric Co.
General Electronic
Laboratories, Inc.
Gray Research & Development Co.
Houston -Fearless Corp.
Intl. Electronic Research Corp.
International Nuclear Corp.
ITA Electronics Corp.
Vir N. James
7
35
28
1
20
13
IFC
Jampro Antenna Co.
40
34
KRIS -TV
39
McMartin Industries, Inc.
Magnecord Div.,
Midwestern Instruments
Magnetic Products Div.,
Minnesota Mining & Mfg. Co
22
Radio Corp. of America
Electronic Products Div.
Victor Records Div.
EQUIPMENT FOR SALE
Transmission line, styroflex, heliax, rigid
with hardware and fittings. New at surplus
prices. Write for stock list. Sierra Western
Electric Cable Co., 1401 Middle Harbor
6-61 tf
Road, Oakland 20, California.
Commercial Crystals and new or replacement crystals for RCA Gates, W. E., Bliley
and J -K holders; regrinding, repair, etc.
BC -604 crystals. Also A. M. monitor service. Nationwide unsolicited testimonials
praise our products and fast service. Eidson
Electronic Company, Box 31, Temple,
9-61 tf
Texas.
-
GOVERNMENT SURPLUS, NEW 10 CM.
WEATHER RADAR SYSTEM Raytheon,
275 KW peak output S band. Rotating
yoke P.P.I. Weather Band 4, 20 and 80
mi. range. Price $975 complete. Has picked
up clouds at 50 mi. Wt. 488 lbs. Radio Research Inst. Co., 550 5th Ave., New York,
5-62 8t
New York.
PHILCO MICROWAVE LINK. 7 KMC System. Type CLR-6 also in stock: Repeaters,
12 and 24 channel multiplex. Large quantity. Exc. cond. Radio Research Inst. Co.,
5-62 8t
550 5th Ave. New York, N. Y.
RCA TT -5 tv transmitter, low band, good
condition, presently on air. Plans and/or
service available for air conversion to
Amperex 6076. Good assortment spare parts
included. P. O. Box 429, Redwood City,
California, or call, area code 415: 369-4675.
8-62
D. C.
It
30
BUY, SELL OR TRADE
9
Will buy or trade used tape and disc reAmpex, Concertone,
cording equipment
Magnecord, Presto, etc. Audio equipment
for sale. Boynton Studio, 10 BE Pennsyl4-62 6t
vania, Tuckahoe, N. Y.
BC
3
Raytheon Co.
Rohn Systems, Inc.
27
39
Saxitone Tape Sales Div.
Sparta Electronic Corp.
Stancil-Hoffman Corp.
Superscope, Inc.
Sylvania Electrical Products, Inc.
34
37
40
Television Zoomar Co.
35
Visual Electronics Corp.
23
-
MISCELLANEOUS
21
29
-
-
-
Low Cost Easily Built
Complete schematics, instructions 50c.
Denson Electronics, Rockville, Conn.
TV CAMERA
JOHN H. BATTISON & ASSOCIATES
1329 E. St.,
John Battison & Assoc.
Bauer Electronics Corp.
Belden Mfg. Co.
Broadcast Electronics, Inc.
Advertising rates in the Classified Section
are ten cents per word. Minimum charge is
$2.00. Blind box number is 50 cents extra.
Check or money order must be enclosed
with ad.
The classified columns are not open to
the advertising of any broadcast equipment or supplies regularly produced by
manufacturers unless the equipment is used
and no longer owned by the manufacturer.
Display advertising must be purchased in
such cases.
7-62 3t
ENGINEERING And Art Degrees earned
through home study. Electronics, Mechanical, Liberal Arts. When writing specify
course desired. Pacific International College of Arts & Scenes, primarily a correspondence school. Resident classes also
available. 5719-W Santa Monica Blvd.,
Hollywood 38, California.
8-62 6t
BROADCAST ENGINEERING
40
www.americanradiohistory.com
New, from Electro -Voice! Sentry Series Professional Monitor Loudspeakers ...
guaranteed flat ± 3 db from 40 to 20,000 cps!
No longer must you improvise with theatre or home-type hi-fi speakers designed
for some other purpose. Gone is the guesswork when equalizing ... you know
you'll get exactly what you hear through an E -V Sentry Monitor. That's because each
Sentry is simple, reliable and as flat in response as modern science can make it!
Gone are "balance" switches or knobs that vary response ... each Sentry
flat at the And laboratories before you everh see
hear it! And because of this simplicity, the
Series speakers are modest in size and price.
E-VSentry
AUTHORITY!or
is
adjusted
NEW VOICE OF
The natural -finish hardwood cabinets are available in a sloping -front style for wall
or ceiling mounting ...or in an upright floor model for fixed or portable
applications. They are all identical in sound. Built-in
transformer matches studio output impedance of 8, 16 and 600 ohms.
[f you want to end equalization guesswork ... if you want to know that the
sound you hear is an exact duplication of the original ... the E-V Sentry Series
Professional Monitors were designed for you. Write for complete
specifications, or see your E -V Professional Products Distributor, today!
Sentry lI Floor Model. 32"H. 23'
ELECTIO-VOICE, INC
W.
13"D. List Price $248.33. Sentry I Wall or Ceiling Model, 17"H, 37'W, 2l3' 'D. List Price $231.67. (Normal trade discounts apply.)
Commercial Products Div., Dept. 821V, Buchanan, Michigan
www.americanradiohistory.com
The Voice of the Land
It's a big land .... a proud land ... that sweeps from sea to
sea. Only a strong voice can fill it ... reach it ... move it to
its very heart.
Listen to this voice. It talks to motorists as they crowd
the busy roads. It gives a warning to farmers that frost is
ahead. It sings a sweet song to lovers. It carries the news
to businessmen. It wakes millions every morning and sends
them off to work ... informed ... entertained ... often inspired. For this is a practical voice, a spiritual voice, the very
voice of America. It is the voice of AM Radio.
RCA has played an essential part in the steady progress
50
KN Ampliphase
5/M1
of AM. You will find the RCA nameplate proudly affixed to
transmitters whose owners never toy with quality ... never
compromise with dependability. You will find the RCA nameplate your highest assurance of superior performance no
matter what your broadcast requirements may be. Why not
call in your RCA Broadcast Representative today. He speaks
your language.
KW Type BTA-511/10U
The Most Trusted Name in Radio
5
KW Type BTA-5T
250/500/1000 W Type BTA-1R1
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