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December, 1975/75 cents
FM TRANSIENT
RESPONSE
page 38
Counting On Counters
Comparing AM Techniques
Function Generators
www.americanradiohistory.com
`Unmistakably
`Warrl`Beck
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\NB BI
Tomorrow's Technology Today.
Ward -Beck Systems Ltd., 841 Progress Avenue, Scarborough, Ontario M1H 2X4
Telephone (416) 438 -6550. Telex 06 -23469
Ward -Beck Systems Inc., 290 Larkin Street, Buffalo, N.Y. 14210
For More
Details Circle
(I)
on Reply Card
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And you also get all these important features:
Individual pots adjust line input sensitivity as
required for Broadcast, CCTV and Hi Fi
equipment.
Bridging or matching inputs (all equipped with
XLR's) and low impedance outputs.
All 7 inputs are Line or Mic switchable.
Test oscillator (1 KHz) built -in ... and with
separate input.
Headphone jack on front panel.
Cermet pots for gain control.
Audio crosspoints ... solid state.
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Distortion: < 0.5%, 30Hz -20KHz (Limiter off)
Noise: -116dBm equiv. input noise
Input Levels: (Max) 100mV p -p Mic; +18dBm Line
Output Levels: (Max) +18dBm into 600 ohms
Power: 110/223 VAC, 50/60 Hz (switchable)
Dimensions: 2 RU's x 7" deep; Desk or Rack Mount
Sure it can be used as an Audio Mixer ... but what
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In the Mix /Follow Mode, the AFM -10 beautifully
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For remotes
the Comp /Lim automatically
maintains Telco Line levels.
performs
a
.
As an Audio Mixer, the AFM -10 handles many jobs
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For More Details Circle
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(4)
on Reply Card
BROáDCáST I11GIC1eeRlllG.
The
21
journal of the broadcast -communications industry
Comparison of AM Techniques. First of a 2 -part
series on AM modulation techniques. It has not been
until recently with advances in materials that newer
systems have become economically advantageous.
Glen Clark.
December, 1975
Volume
17, No. 12
About The Cover
The photo this month
and the articles are
focused on tests and
measurements that
concern us all at the
26
Counting on Counters. Counters are invading the
communications facility. It's about time. Our maintenance editor explains how they can be used to
advantage. Pat Finnegan.
Function Generators To The Test. Notes on
what a function generator is, how it compares with
other test equipment, and what it can tell you about
broadcast circuits. Walt Jung.
32 Let's Put
38 Transient Response, Part 1. First part of a series discussing FM transient response. In this first part, our
audio editor covers filters and their effects upon
signals. Dennis Ciapura.
43 Rapid Frequency Response Measurements. The arti-
cle tells how to take the drudgery out of measurements, using a real time analyzer and a pink noise
generator. Elmo Reed.
Walter Jung, Solid State
CIRCULATION
Evelyn Rogers, Manager
WCVB, Boston).
Departments
Direct Current
4
Industry News
8
SBE Journal
14
People In The News
51
New Products
52
Tech Data
61
Ad Index
62
Classified Ads
63
Engineering is published monthly by
intertec Publishing Corp., 1014 Wyandotte Street,
Kansas City, Missouri 84105.
Telephone: (913) 888 -4864
B roadcast
EDITORIAL
Ronald N. Merrell, Director
Carl Babcoke, Technical
Pat Finnegan, Maintenance
Howard T. Head, FCC Rules
Robert A. Jones, Facilities
communications facility.
(Photo, courtesy of
Sharon Elwood, Editorial Assistant
H. G. Roesler, Cartoonist
Dudley Rose, Graphic Designer
Joe Rotzen, Video
Archer Taylor, CA TV
Dennis Ciapura, Audio Editor
ADVERTISING
Mike Krelter, Director
Jean Cornwell, Production
Regional Advertising Sales Offices on
Advertisers' Index paga
Broadcast Engineering Is mailed free to qualified
persons engaged in commercial and educational
radio and television broadcasting. Non-qualified
subscriptions In the U.S. are $6.00 one year,
$10.00 two years, $13.00 three years. Outside the
USA add $1.00 per year to cover postage. Single
copy rate 75 cents. Back Issues rate $1.00.
Adjustments necessitated by subscription termination at single copy rate.
Controlled Circulation postage paid at Indianapolis, Indiana.
Robert
Copyright, 1975, Intertac Publishing Corp. All Rights Reserved: Material may not be
reproduced or photocopied in any form without written permission of Publisher.
2
E.
Hertel, Publisher
INTERTEC PUBLISHING CORP.
Subsidiary of HOWARD W. SAMS 8 CO., INC.
BROADCAST ENGINEERING
Introducing the
M22)
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The 3402 gives exceptional performance
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A two -rack unit mounting tray, illustrated
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V p -p
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Chrominance /Luminance Delay
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FOR ADDITIONAL INFORMATION, CONTACT:
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(516) 487 -1311
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December, 1975
3
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DIRECT
CENT
(.
¡rt.
.:.
,;;iïllÜld1`àfi
--
D. C.
December, 1975/By Howard T. Head and Harold L. Kassens
Commission Bars Restrictive Program Agreements
1973, the FCC issued a Notice of Inquiry looking into
subscription agreements between broadcast stations and companies
supplying taped musical programs. What appeared to be worrying
the Commission was that the agreement required the station to
operate a minimum number of hours a day; prohibited SCA programming or AM /FM duplication; required a fixed number of minutes
of supplied music each hour; prohibited announcement of names
of musical selections; limited the number of commercials per hour;
prohibited triple- spotting; required all talk programming to be
public affairs or religious; required news to be a certain percentage (or less) of total air time; and limited the number of
We even heard of a case where
newscasts during certain times.
the
use
of a certain type transmitter
required
music
supplier
the
because it sounded "crisper "!
In May,
Of particular interest to engineers in this matter is the SCA
prohibition.
Some time ago, many FM stations operating with both
stereo and SCA were getting complaints of a 9 or 10 kHz "birdie"
caused by the 3rd (57 kHz) or 4th (76 kHz) harmonic of the 19 kHz
stereo pilot subcarrier beating with the 67 kHz SCA signal.
Stations transmitting classical music with a large dynamic range
were particularly vulnerable. After a careful and detailed study,
it developed that the effect was primarily a receiver problem
brought about by a lack of, or misadjustment of, a 67 kHz SCA trap.
At the time some stations used this information to get out of the
background music business and, it appears, some of the music program
suppliers would not permit the use of an SCA. The FCC has now
resolved the problem by issuing a policy statement which, in effect,
What
bars contracts which prohibit subcarrier authorizations.
they plan to do about the receivers they haven't said.
Realism in AM Allocations Involving Caribbean Area
Recent Commission actions might help favorable action on applications for nighttime operation involving foreign stations in the
In cne case, the FCC noted that although a
Caribbean area.
Cuban assignment was duly notified (pre- Castro), the Foreign
(Continued on page
4
6)
BROADCAST ENGINEERING
None for the money...
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Sparta
AC155B/
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Any
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even our competitors sometimes buy them!
Instead of offering the familiar comparison of our equipment versus others' in this space, in all fairness we can only
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we cannot.
Sparta
Any
AC155B/
ASC305B
Other
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2
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Stereo (ASC305B) with 9 inputs
Custom instant -start turntables
Micro-balanced tone arms
Furniture -grade cabinetry
Matching utility shelf accessory
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Lift -leaf table extension
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Pushbutton multiple input selector
Studio quality audio performance
Console removable battery-operable
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Cue (all mixers) to built -in speaker
Muting standard
Sparta's innovation leadership in creating
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Telex 377-488
For More Details Circle
(5)
Cable SPARTA
on Reply Card
December, 1975
5
www.americanradiohistory.com
DIRECT CURRENT
FROM D. C.
(Continued from page
4)
Broadcast Information Service, the World Radio Handbook, and
listening tests made by an AM station and the FCC monitoring station
The FCC
all indicated that the Cuban station was not in operation.
granted the application of the AM station to add nighttime operation on condition that protection would be required to be afforded to
the Cuban station if it should start operation again.
In another case, an AM station had its application to add nighttime
operation originally denied by the FCC because it would only serve
74% of the population and 49% of the area of the city at night.
Upon
appeal, the U.S. Court of Appeals sent the case back to the Commission, which then granted it with the explanation that:
(1) the
city is large; (2) it is irregularly shaped; and (3) it has expanded
markedly in recent years.
Next:
"Ball Game" Radio?
The Commission has instituted an inquiry into the possibility of
opening a new broadcast service at sports events which would
transmit information on the progress of the game to spectators.
As it did so, it denied a request for an authorization in the
Business Radio Service to provide spectators at professional golf
tournaments with information as matches progressed. The applicant proposed to use the frequency 154.570 MHz and to rent receivers to the spectators.
The FCC said it was opening the inquiry
because of the continuing interest in this type of service.
Short Circuits
In a paper- saving drive, the FCC has reduced the number of copies
of papers required to be filed in certain FCC proceedings; petitions
for rule- making to add or change FM and TV channels now only require an original and four copies rather than the former fourteen
copies
The Commission returned a petition for rule- making
proposing a Class D (10 Watt) educational FM station in the
commercial portion of the FM band, on the grounds that it was
short - spaced
A developmental authorization has been granted
in the business radio service for remote reading of public utility
meters in a New York county, using 928.050 and 937.550 MHz for
2 fixed stations,
35 fixed relay stations and 625 meter -attached
.
.
.
.
.
.
transmitters.
BROADCAST ENGINEERING
6
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The Effects You NeedAt a Price You Can Afford...
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IEL
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Sideband Analyzers Video Test
Signal Generators Envelope Delay
Test Set Differential Phase and Gain
Measuring Systems Remote Control
Vertical Interval Test Sets Video
Sweep Generators Modulators
Demodulators -Fixed Frequency
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Signal Conditioners Audio Monitors
Audio Distribution Amplifiers Video
Distribution Amplifiers Pulse
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Amplifiers Monoscope Generator
Video Routing Switchers Video
Production Switchers Chroma
Keyer-RGB Chroma Keyer
Decoder -NTSC
For More Details Circle
December, 1975
r
(6) on Reply Card
COMPANY
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(516) 842 -2300
TWX 510- 227 -9850
I
IO.K. Telemet send me the following:
Information on Model 7960
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Please put me on your Technical
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NEWS
Radio Deregulation Derailed?
VERSA CONSOLE
Compact rack -mount single channel mixer ideal for CATV, CCTV,
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Line and PA outputs.
50 SERIES MONO
Complete small console for production, on -air, educational or
CATV use. 8 switch selectable inputs to four sealed mixers with
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Rack
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100/200 SERIES
MONO & STEREO
occupy the halls of Congress and
the FCC on behalf of their special
The president of the National
Association of Broadcasters and
interests."
chairmen of two NAB radio committees, appeared recently before
the Senate Communications Sub committee and testified in support
of the Federal Communications
Commission's deregulation of radio.
Representing the NAB before the
committee were President Vincent
T. Wasilewski, Richard W. Chapin
of the Radio Reregulation Committee and Wayne C. Cornils of the
Small Market Radio Committee.
Wasilewski told the committee
The NAB president also said
NAB agrees with the FCC reinter-
pretations of Section 315 and
welcomes these relaxations regarding broadcast coverage of debates
and press conferences.
Wasilewski stated that NAB sup-
ports the experimental suspension
of the Fairness Doctrine, pointing
out that the experiment "ought to
include at least some small markets
if the FCC is to obtain the most
meaningful evidence possible and
make it a true test of licensee
responsibility."
Chapin, president of Stuart Enterprises, Lincoln, Neb., and former
chairman of NAB's Board of Directors, urged the committee to encourage the Commission to accelerate its efforts in deregulating radio.
that the Commission's plan is
working and that "a handful of
well- meaning special interest groups
should not be allowed to derail it."
He added that "broadcasting is
for all the people -not just for
those foundation- funded groups
which have the know -how and
economic backing to constantly
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Full dual channel consoles with
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SILVER SPRING, MD. 20910
PHONE 301- 588 -4983
on Reply Card
optimum stereo and
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zero bias, grounded grid PA
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standard features include
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superb bandwidth characteristics
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(7)
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McMartin engineering has supplied
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McMartin.
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(65) on Reply Card
BROADCAST ENGINEERING
8
www.americanradiohistory.com
Digital rotary patterns.
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MORRELL BEAVERS Midwest
2644 North Seventh St.
Terre Haute, Indiana 47804
Phone 81&466-3212
ROBERT McALL Northeast
34 Autumn Lane
Hicksville, N.V. 11801
Phone 516/735-0055
N E.
53rd Ave.. Gainesville. Fla. 32601
GORDON PETERS Southwest
P. 0. Box 912
Arlington, Texas 76010
Phone 817/261-6855
ERIC KING
Fox Hill Road
Lynchburg, Va. 24503
Phone 804/384-7001
Phone 904;378-1581
RICHARD RODGERS West Coast
7960 West Beverly Blvd.
Los Angeles. California 90048
Phone 213!653-9438
for More Details Circle (8) on Reply Card
December, 1975
0
www.americanradiohistory.com
A
Two FaCed
EquaIîr
You Can
Trust.
NAB
Agrees With
Commission
The National Association of
Broadcasters has asked the U.S.
Court of Appeals for permission to
intervene in a court test of a
Federal Communications Commission order exempting certain political debates and on- the -spot coverage of news conferences from the
equal time provisions of Section
315.
NAB said in a motion filed in the
U.S. Court of Appeals for the
District of Columbia that it seeks
an opportunity to show that the
FCC order reversing earlier rulings
of 1962 and 1964, "promotes the
public interest and represents a
correct reading of Congressional
intent."
The Model 530 Dual Graphic Equalizer is two completely independent Graphic Equalizers with a common power supply. Each
channel begins with a differential input stage, followed by nine
variable equalizers centered at each octave from 50 Hz to 12.5
kHz. The transformer isolated outputs are capable of delivering
+20 dBm into a 600 ohm load. The bridging inputs may be fed
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and at a two for one
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...
The motion said NAB's objective
"the maintenance of the broadcast industry's ability to serve the
public" and to "avoid the undue
stifling of broadcast coverage of
news events involving candidates for
public office which has occurred
over the course of the past thirteen
years."
The motion was filed in a consolidated case in which the Democratic National Committee, Rep.
Shirley Chisholm (D-N.Y.). the National Organization for Women and
others challenge the FCC ruling.
is
Cable....Again
The National Association of
Broadcasters has proposed that
cable television systems be permitted to carry specialty programs
broadcast by specialty format stations on a regulated basis.
However, the NAB suggested to
the Federal Communications Commission that such carriage be on a
program -by- program rather than a
station -by- station basis. The NAB's
proposals were submitted in response to various Commission
proposals for deregulating carriage
of special format stations or programs.
In its tiling, NAB noted that there
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Exclusive export agent: Gotham Export Corporation, New York
For More Details Circle
(9) on Reply Card
10
www.americanradiohistory.com
now are three recognized classifications of specialty stations: foreign
language, religious oriented, and
those which devote day time programming to financial reports.
BROADCAST ENGINEERING
HOW TO GETA SECOND CAMERA
WITHOUT PAYING FOR IT
Economic realities being what they are,
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Logical question. For which we have a
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comes complete with all controls, accessories, and protective cases. Like the other Versatility Packages we offer for other formats,
it's a great way to keep your cameramen
happy. Without upsetting your controller. For
more information, please write or call.
'
Canon
Canon U.S.A. Inc.
Head Office, 10 Nevada Drive,
Lake Success, N.Y. 11040
140 Industrial Drive Elmhurst, Ill. 60126
123 Paularino Avenue East,
Costa Mesa, Ca. 92626
Canon Optics & Business Machines
Canada, Ltd.
3245 American Drive,
Mississauga. Ontario. L4V 1B8, Canada
Canon Amsterdam N.V.
Industrial Products Division
De Boelelaan 8, Amsterdam, Netherlands
*
For More Details Circle
<%N.V.
Philips of Holland
(10) on Reply Card
December, 1975
11
www.americanradiohistory.com
AVR-2 your I
Over 400 unit:
The bottom line is this:
Higher productivity in the
tape room means
increased operational
economy and a better
on -air look.
How does AVR -2 help?
Simpler design, for one thing,
inside and out. It lets your
operator function at top
efficiency, regardless of his
experience or workload. Look
at the design and location of
controls shown here for proof.
Contact your local Ampex
sales representative for more
information on how to improve
your bottom line.
AMPEX
Ampe> Corporation
Audio-Video S\,.tems Division
401 Broadway
Redvoo(j it\. Calitornia 94063
12
BROADCAST ENGINEERING
investment.
in use prove it!
:st
Operational and Editing Controls
i
MI controls are on open, visible
panels. Operational and editing controls are user -located at fingertip level,
so your operator (experienced or not)
is never confused by exposed electronics.
Fast editing ICs easy to align the playback of AVR -2 "to match the new program material from any camera, tape
machine, or remote telco line. The
program doesn't even have to be synchronous with your system!
Your operator simply pushes one button and sets one control to line up ver-
tical lines on
a
unique split screen
display. Result: fast, easy, perfect edits
-especially for inexperienced operators. And all from one control panel.
Secondary Controls
Playback equalization and differential
gain controls- necessary in highly
critical editing operations -are located
conveniently on a tilt -out panel to allow for quick playback setup.
Video head optimizing takes less than
a minute on the AVR -2. Its a simple,
one -hand operation, as easy as tuning
a home hi -fi receiver.
Setup Controls
Instant visibility, accessibility, change a cinch on
AVR -2 because everything is clearly
marked and accessible. There are no
confusing, unmarked boards or flash=
ing lights.
ability. Maintenance is
You can operate most AVR -2 set -up
controls in unity (fixed position) with
the door closed, for normal operation
or inexperienced operators.
-or open the door and quickly switch
into variable operation to adjust for
any unusual condition. Switches are
locking type toggles, so a knee -bump
can't change their position. And don t
worry about air circulation, either.
AVR -2 is air -cooled whether the door
is open or not.
For More
December, 1975
Details Circle (11) on Reply Card
13
ing and will offer four hours of
technical papers. as well as exhibits.
Specifically. registration will begin on Thursday. December 4, at
3:00 p.m. and swing into the
SOCIETY OF BROADCAST ENGINEERS, INC.
P O Box 88123
Indianapolis. Indiana 46208
From The SIGNAL
Attention Chapter Chairmen: If
you need additional copies of The
Office in
Washington, D.C.
Signal to distribute at Chapter
meetings. please drop a note either
to Vince Flanders in Indianapolis
Hope everyone has been receiving or to The Signal office at 2000 N
his copy of The Signal regularly, Street, N.W., Suite 210, Washingbecause another issue will be of ton, D.C. 20036.
interest to members. The SBE
Certification Program was finalized.
and the formal rules were published
in the November issue. Now The
Signal is preparing to notify mem- In The
bers of the Society's position with
Chapter 9 is putting the final
respect to the "automatic transmitter system" docket which is touches on its December Regional
currently before the FCC. We will Convention at the Sunburst Hotel
be printing this statement as soon in Scottsdale. This event will be
as the SBE Board formalizes its held concurrently with the Arizona
stand.
Broadcast Association winter meet-
Regional
Convention
Southwest
evening with an invitation to the
ABA Associate Night. Friday will
start with registration at 8:30 a.m.,
followed by a technical session at
9:15 and exhibits opening at 11.
Friday afternoon offers a lunch-
eon. another technical session,
cocktails, and an evening banquet.
Exhibits will continue on Saturday,
December 6, until 2:30 in the afternoon. A partial list of exhibitors
shows that Ampex. A/V Recorders,
Broadcast Communication Devices,
Grass Valley. Lenco, Microwave
Associates, RCA, Roh Corp., Tektronix. Tritronics. Sony Corporation, Sparta. and Zonar will all be
there.
Before finalizing your own plans,
please be sure to check with AI
Hillstrom at KOOL -TV, 511 West
Adams. Phoenix, Arizona 85003,
(602) 257 -1234, for the last- minute
changes. The above information
(Continued on page
16)
PROFESSIONALS SPECIALIZE
..,I..,,RO..
3911:93aSem
I
.9561
.._
El
MODEL 367
SMPTEmat Switcher
Color Switcher
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SMPTE Edit Code
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Interface Panel
o
111
Post Production Switcher
CHROMATIC DUET
VS4,3Zo
A $3,500
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Special Effects Generator
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Dissolve to Effects
Built -in Color Back10 Basic
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Over 1000 Units Sold
Production Switcher
... The Precision People
SH,NTRON
Cambridge,
MA 02142
(617)491-8700
For More Details
14
Circle (12) on Reply Card
BROADCAST ENGINEERING
Harris
dual TV transmitters
proven for unattended
operation.
In more than 25 cities in 17
states, Harris dual VHF tele-
vision transmitters, operating
in parallel or alternate /main,
provide complete redundancy
for maximum on -air time.
And only Harris provides
automatic switchable modulators, switchable low -level
VSB and switchable color correction for 100% redundancy.
If one transmitter should fail,
its twin keeps you on the air.
And full time ... air time is just
one of the advantages of
parallel operation.
For More Details Circle
For complete information,
write Harris Corporation,
Broadcast Products Division,
Quincy, Illinois 62301.
rri HARRIS
W
COMMUNICATIONS AND
INFORMATION HANDLING
(13) on Reply Card
December, 1975
15
www.americanradiohistory.com
Sportscaster
Headset...
Color, Action,
Hands-free
Mobility
Combine the finest omnidirectional dynamic boom mike with
an equally high performance binaural headphone and you have
the superior Sportscaster head set...the Telex CS -90. For live
broadcasts, from the station or on
remotes, with cue and program
monitoring and hands -free convenience. The audience hears
every word, clearly, crisply, with
crowd noise for background color
and atmosphere. Circumaural ear
cushions screen out noise in the
immediate area so that special
acoustic facilities are unnecessary.
Supplied with convenient in -line,
mike -muting "push-to-coughswitch. The Sportscaster headset.
Color, action and hands -free mobility. For complete
information please
write:
_M
needless confusion.
came together t'or the event.
Today the group consists of radio
broadcasting and television station
people. station engineers, and consulting and service engineers. It
originally started out to meet as a
weekly "luncheon and discussion"
group. and this has worked out
quite well. For several years now
Another Chapter
In The Making
the Chapter has been meeting
during the Monday noon hour
when all technically oriented people
are invited to attend, including any
socif
n
r
TELEX.
C O
M M U N
I
C A T
I
O N S
I
NC
9600 ALDRICH AVENUE SOUTH
MINNEAPOLIS. MINN 55420 U.S A.
Europe: 22. rue
dèHOnneur.
Ste la LleB FaCanada: Telak Electronics. Ltd Scarborough. Ontario
For More Details Circle
OF
0. 66r}]
E
ENGERS NC
iMaad
.6?J6
Continued from page
14)
was taken from a tentative schedule
only, and a quick call may save
8887.
traveling people who might have
that hour open. Several evening
meetings are also planned during
the year. and they have always
produced a good turnout.
Last spring. Mr. Pritchard of
KREM and Mr. Valley of KSPS
discussed digital remote- control systems which led into a lively discussion on automatic transmitter controls.
On another occasion, Mr. Pritchard. chief engineer of KREM -TV,
invited everyone to come to the station to see a tape recording of the
new Gamma correction system to
be employed in the RCA TK28 film
camera.
Chapter 21 also takes time out to
honor the "old timers." Last year,
Chairman Jorgenson wrote a letter
honoring Mr. Langsford on his
72nd birthday, reviewing his long
career in radio and television. The
Chapter also tries to advertise its
consultants and technical people
who service their stations.
In the future. we hope to be
hearing more from Mr. Jorgenson.
He tells us that he has some nearly
finished articles on Mt. Spokane,
where KXLY -TV and FM, snowed
under and iced in for over half the
.year. operate a station at 6,000 feet
AMSL. Also, he's tendering an
article on simple microwave tests as
soon as he completes his search for
SBE Chapter
photos. We hope to be publishing
these soon in one of The Signals.
The San Diego Chapter is apparently going to get a new neighbor. The Signal was advised of the
formation of a new group in San
Francisco. Two meetings have already been held, and official recognition may come after the third
meeting -way to go. Californians!
The first gathering on September
9 heard guest speaker Frank Miller
of Sescom, Inc., discuss audio
transformers, their construction and
application, via a slide presentation.
The second meeting was held
October 8 when Bob Morrison of
Standard Tape Labs (a nationally
known manufacturer of precision
alignment tapes, located in the Bay
area) was invited to lead the pro gram. Mr. Morrison spoke on the
new NAB standards proposed for
tape cartridges and elicited some
pretty lively comments and questions.
The next meeting was yet unannounced, but one of the items on
that program is the election of
officers.
For further information about
this new and upcoming chapter,
please contact Mr. Robert B.
Daines. Western Region Manager,
I'elentet, Western Region Office,
1261 El Curtola Blvd., Walnut
Creek. California 94595, (415) 938-
In
PRODUCTS OF SOUND RESEARCH
and power company representatives, communications departments,
CATV, and translator people all
appropriate circuit prints and
Profile
Chapter 21: Spokane, Wash.
Chapter 21 was founded in 1968,
and everyone involved in the radio
and television broadcast system was
invited to attend. Radio and TV
station engineers, receiver servicemen. parts distributors, telephone
CHAPTER
MEETINGS
Chapter 2: Northeastern Penn.
Members of Chapter 2 met
Monday evening. October 6, at the
WVIA -TV and FM studios in
(Continued on page 50)
(14) on Reply Card
BROADCAST ENGINEERING
16
www.americanradiohistory.com
Fewer parts...
fewer problems with
A-2
broadcasftartridge
Ribs are molded into the flange
no pencil leads
to break and jam.
-
No top wire.
Reloading's easier.
Tape guide is
an integral part of
the cartridge base
- not glued in -
to insure accurate azimuth control.
Try
one free
In the broadcast cartridge world, the simpler the
better. That's why the design of the audiopak A -2
eliminates parts that can give you trouble.
The lessons learned from our years of experience developing the world's leading 8 -track cartridge have been applied to our audiopak A -2. The
result is a more durable, more reliable broadcast
cartridge. And because we manufacture the entire
product from tape to packaging -we can assure
you of the highest possible quality control.
We're so sure we have the best product on the
market, we want to prove it ...at no cost to you. For
your free sample and more information on the
audiopak A -2 broadcast cartridge, write on your
company letterhead to: Capitol Magnetic Products, Division of Capitol Records, Inc., 1750 North
Vine St., Los Angeles, Calif. 90028. Attention:
Marketing Manager, Professional Products.
-
For More Details Circle
December, 1975
CAPITOL MAGNETIC PRODUCTS
//,,,,,,,,,
Capitol
A DIVISION Of CAPITOL RI CORDS INC
LOS ANGELES. CALIFORNIA 90028
A MEMBER OF THE EMI GROUP
EMI
(15) on Reply Card
17
Some day,
somebody
may imitate
fhe Product..
18
BROADCAST ENGINEERING
...but nobody
will ever
-
s
"
duplicate
the Service!
And inTVBroadcasting,
its the service behind
the product...that keeps
the product out front
On the way to selling more than 30,000 Plumbicon TV
camera tubes, we learned how important Service is to the
broadcaster. The first thing we learned was about
availability No TV station, commercial or educational,
can ever afford to shut down an operation while "waiting
for parts." Plumbicon tubes are instantly available, at all
times, through local franchised distributors and through
Amperex factory sales representatives.
And we learned the importance of the name Plumbicon
to TV stations who have come to depend on it as their
assurance of consistent performance and quality.
Because no product is ever 'good enough," we taught
ourselves to build smaller and smaller Plumbicon tubes
that provide performance standards similar to the original
(we're down to 2'3 inch tubes now.) and we learned to
produce tubes with reduced comet tailing, with higher
resolution and modulation depth. with extended -red
response, and with minimum lag. Contemporary camera
tubes outperform the original Plumbicon by a wide margin.
We learned that the TV camera user is concerned about
the operation of his camera ... not merely about the
performance characteristics of our tubes. So we provide
him with a wide range of expert and valuable information,
in print and via our field engineers, to help him get the
most out of his TV camera- system. Plumbicon users
who are about to install a new camera need only give our
-
For More
field engineering staff a call and we'll have an expert
there to help with the job.
Our franchised distributors, (your own local businessmen,) are carefully selected for their ability to support
Plumbicon TV camera systems with on- the -spot customer
support and service. We, in turn, support our distributors
with two kinds of "seminars" for Plumbicon camera
users. One is on video tape, the other is presented "live"
by an Amperex field engineer. The purpose of both is to
maximize the value of Plumbicon camera systems.
Finally, we learned that the best way to deal with warranty
questions was to design the warranty for the customer's
benefit not to protect ourselves ...and even then, to
interpret the warranty in the customer's favor whenever
possible. For example. a customer may return any
Plumbicon tube for testing (even one that's technically
out of warranty) and we'll subject it to a complete technical
evaluation at our expense ... and send the customer a
detailed engineering report on the tube.
Yes, we've learned a lot about the importance of Service
in the ten years, in the more than 30.000 tubes sold, in the
600 -plus TV stations served, since the Plumbicon tube
won the Emmy award. Little wonder, then, that the
Plumbicon, after all this time, still offers the best all- around
package of performance. price. reliability and service
available. Little wonder, then, people keep on saying,
"There's only one Plumbicon."
Electro- Optical Devices Division, Amperex Electronic
Corporation, Slatersville. Rhode Island 02876,
Telephone: 401- 762 -3800
-
Amperex
A NORTH
.A
ci'
PI
Ill IP'
There is only one Plumbicon
Details Circle (17) on Reply Card
December, 1975
19
www.americanradiohistory.com
.__l IrüDL
OE
SQUARE
WAVE
CARRIER
OSC
OC
OD
GEN No.
inn
1
TRIGGER
OB
AUDIO
SQUARE
AMP
WAVE
GEN No.
2
A
9
1350
y 450
B
C
r
D
E
Figure
4
United States now do not use plate
modulation.
The following comparison of all
four systems details the reasons for
the trend away from plate modulation, why it may be expected to
continue, and what the advantages
of the new systems are.
OUTPUT
CONVERSION
FUNCTI ON
INPUT
CONVERSION
FUNCTION
OUTPUT
CONVERSION
FUNCTION
INPUT
CONVERSION
FUNCTION
IBI
(AI
INCREASING PHASE
Figure
5
crystal oscillator output, respectively, such that the audio power
will be equal to one -half of the dc
6
input power to the final RF amplifier. The ac audio signal is then
superimposed upon the dc B+
voltage on the plate of the power
amplifier (PA) by a modulation
transformer. The PA plate voltage,
and hence the RF output, will vary
or be modulated in accordance with
the audio signal.
Classically, the plate -modulated
transmitter employs one or two PA
tubes operating in class C. and two
E
T¡
r
22
E
J
IAI
Figure
Plate Modulation
The plate -modulated transmitter
has two primary signal paths, the
audio -frequency (AF) and the radio frequency (RF) chains. They amplify the program audio and the
IBi
BROADCAST ENGINEERING
.
Input-output configurations are virty'ally unlimited
with this
'
`
audio switch. And
this flexibility oon6es at
/
N.
nnnn"w=
/
-
^
.14-3
-`
i
1
sutstandinq Using field effect
transisiiir .sdiching and integrated
Series-8100 handles -6 to +8 dBril levels through
reduced cost.
50 kHz), crosstalk (beiter tVan 70 dB below
output), harmonic distortion (-*,s than 0.15%) and
hum and noise (85 dB below maximuM output)
the 8100 compromises nothing for its flexibility.
Best of all, users will really appreciate the
economy. By specifying the initial capability for
any remotely-controlled, switched audio distribution network, the buyer saves now and isn't
penalized later. High reliability solid-state audio
switching costs can be cut to as little as $10 per
orosspVint.
significantly less than competitive
switching systems.
Write today for complete details.
.
Starting with a single 8%-inch by 19-inch rack
frame assembly, the user can build to a 20'input
by 20-output configuration through selection of
plug-in switching and amplifie boards.
Still using the same basic frame assembly, other
configurations such as 20 by 5, 10 by 20 or combinations in between can be assembled. Greater
capacities, including dual inputs or outputs, are
just as easy
.juotadd.
Control? ... asnap! pushbuttons, thumbwheels,
dials, touch pads.
even a computer.
.
.
.
.
www.americanradiohistory.com
.
DYNAIR ELECTRONICS, INC.
6360 FEDERAL BLVD., SAN DIEGO, CA. 92114
PHONE: (714) 582-9211; TWX: (910) 335-2040
For More Details Circle
(19) on Reply Card
`
push -pull modulator tubes operating in class B or AB. as in Fig. 1.
Some torn of internal audio feedback is normally employed, sampling the audio signal immediately
before the primary of the modulation transformer, and feeding it
back out of phase. to some point
early in the audio chain.
Efficiency of the PA's is normally
high; that of the modulators, low;
thus the overall efficiencyis moderate. A typical plate -modulated 50kW transmitter requires 145 -kW
total power input when modulated
at 100 percent with a steady -state
sine wave.
.
4
mn
irsn
ZOZinxZout
Z02
out
Z
Zin
Figure
Ampliphase
7
400%
300%
POWER
SUPPLIED
BY' PEAK"
TUBE
200%
The current trade name Ampli phase system is a refinement of a
system called "outphasing" proposed by Henry Chireix (1) in 1935.
Its basic principle is the vector
addition of the outputs of two
identical RF amplifiers as the relative phase of the two constant
amplitude output waves is varied
(Fig. 2).
When the outputs are in phase
the combined output is equal to the
sum of the two powers. When the
outputs are 180° out of phase they
cancel and the combined output is
zero. At points of intermediate
phase relationship. the combined
output current is determined by the
formula
/=
POWER SUPPLIED
BY
"CARRIER"
2
TUBE
where 0 is the relative phase angle
in degrees and the output currents
T
-50%
-100%
.
0%
50%
.100%
(CARRIER)
MODULATION PERCENTAGE
Figure
8
B.
RFC
2 cos
90° PI- NETWORK
IMPEDANCE INVERTER
of the individual amplifiers are
assumed to be I.
From a system standpoint, Ampliphase can be thought of as two
complimentary conversions: on an
amplitude -to -phase conversion, and
the other a phase -to- amplitude
conversion as shown in Fig. 3.
The phase -to- amplitude or output
conversion is accomplished in the
common output network of the two
RF amplifiers as was shown in Fig.
The input conversion from
amplitude to phase is produced by
an Ampliphase "exciter." A block
diagram of the exciter is shown in
2.
CARRIER
TUBE
Fig. 4.
EXCITATION
INPUT
T
90°
DELAY TO
PEAK TUBE GRID
Figure
9
A triangle wave at carrier frequency is presented at point A. An
audio signal of much lower frequency is presented at point B. The
two are combined at point C, producing a triangle wave with low-
BROADCAST ENGINEERING
24
www.americanradiohistory.com
frequency baseline shift. The wave form is subsequently fed to a
trigger circuit which produces a
pulse train at point D. The repetition rate of the pulse train is that
of the triangle wave (carrier frequency). The duty cycle of the pulse
train varies. however, in proportion
to the audio signal which was
superimposed on the triangle. The
duty cycle 0 is given as
0=
135°
MODULATOR
CARRIER
TUBE
{
PEAK
TUBE
+ y45°
where y is the amplitude of the
audio signal. (While it is convention
to speak of duty cycle in terms of
percent or time, the notation here is
given in degrees because of the
correlation with a subsequent phase
displacement. It is understood that
a duty cycle of 0° is equivalent to
0/360° percent.) This pulse train
in turn triggers two square -wave
generators. The first such generator
triggers on a positive -going zero
crossing of the triggering wave. The
second generator triggers on the
negative -going zero crossing. The
outputs of these two generators
drive the grids of the two RF am-
plifiers.
B.
700 VDC
-300 VDC
Figure
One can readily see that the
phase displacement of the signals
fed to the RF amps (at points E
and F in Fig. 4) is the same as the
positive duty cycle (0) of the pulse
train at D, which is proportional to
the amplitude of the audio input
signal. With no audio input, the
trigger threshold is normally adjusted so that 0 is approximately
equal to 135 °, or carrier condition.
These constitute the two stages of
10
conversion. Unfortunately, in this
form they are not true complements
of one another; the function of one
is not precisely the inverse function
of the other. The input conversion
relationship (2) is
a
linear function.
The output conversion relationship
(1) is trigonometric. Graphed together as in Fig. 5(a), they track
rather closely except at the high
end, where the output function falls
off more rapidly. The net result
(Continued on page 37)
PERFECT TIMING
Programmer/Comparators and Controllers
Whether your station is based in New York, Honolulu or anywhere in between, perfect timing of programs, station breaks
and commercials is essential. To meet your exacting timing
requirements ESE now offers two precision timing systems.
For flexibility and economy with up to ten events, ESE has designed the 750 Series of Programmer /Comparators.
Rugged thumbwheel programmers coupled with an
ESE clock or timer to provide a single pole contact closure (1 Amp contact rating) for the length
of time program matches display. Low on cost, the
reliable Programmer /Comparators start at $305.
Write, Wire or Call Today: 5051/2 Centinela Avenue
For More Details Circle
When you want to program more than ten events, consider
the ES 780 Series of Programmer /Controllers: A Solid State
Random Access Memory united with an ESE clock or timer to
provide 32 user -programmed outputs. Ten minutes is all you
need to program all 32 events. Manual override and ten second re- programming provide maximum flexibility.
All this in 51/4 inches of rack space! Internal
crystal time -base and battery pack are standard
features. Four digit, 32 event units are $1,200.
and Eight digit, 32 event units are $1,500.
Custom options and special orders are available.
Inglewood, California
90302
(213) 641.3021
J
(68) on Reply Card
December, 1975
25
www.americanradiohistory.com
.1
WLBC engineer Steve Brown uses a counter
to measure the frequency of a portable
transceiver on the bench. While the readouts
did not show up in the photo, they usually
are easy to read at some distance.
Counting on counters
o
o
o
o
o
HERTZ
OVERFLOW
CIRCUITRY
RANGE
OVERFLOW
WARNING LIGHT
Fig. 1 When resolving to the lowest units and there are not
enough readouts, the first digits move into the overflow.
When digits are in the overflow circuitry, the unit will either
blink all readouts or light an overflow lamp.
station and those which can be
anticipated. This won't be possible
for all stations. One small counter,
Progress made in solid state for example, may cover 5 Hz to 175
technology in recent years has MHz in its basic range. This will
taken the frequency counter out of cover AM, FM broadcast, subcarthe laboratory category and into the riers, and VHF mobile units.
field. These new portable units are
For those measurements required
very accurate, stable, and the price by FCC Rules, the counter must be
range is very attractive.
calibrated. The best method for 'on
A station will ordinarily buy a site' calibration is comparison with
frequency counter so that it can the carriers of WWV. The model
measure its regular broadcast trans- selected should have some provimitter carriers, as required by the sions for calibration.
The number of readout elements
FCC. Equally important, a portable
counter can be used for trouble- the instrument has does not affect
shooting and maintenance where its accuracy, but it does affect the
accurately known frequencies are number of significant figures you
very desirable or necessary.
can have displayed at one time, and
There are many makes and the operations necessary when remodels in a wide price range. As solving a high frequency signal
with most test instruments, some down to its lowest parts. In some
models will include some secondary units, if the frequency is too high
features that satisfy different in- for the range in use, the figures left
dustry needs.
of the decimal point will 'slide over'
A counter is essentially a 're- into the overflow circuitry and a
ceiver' in nature, and not a signal light (sometimes called an over- generator. although some models range light) flash on to warn the
do provide some fixed output operator that there are numbers in
frequencies that may serve a useful the overflow.
function in your applications. Also.
For example, a mobile unit on
the front end is broadband, so a 166.25 MHz, to be read in its basic
particular signal cannot be tuned units of Hz is: 166,250,000 Hz. If
in. The counter will lock on the the instrument has the typical 6
most predominant signal that will readouts and the range switch set
provide it with enough signal to resolve to its basic lowest units,
(within its range) to make an 250,000 will be displayed, and the
accurate measurement.
over -range indicator will come on.
The 166 will be in the overflow.
Desirable Features
You must switch the range until all
For portable use, the important figures are out of the overflow.
features to consider are: basic
When checking mobile units in a
range, method of calibration, read- vehicle, instrument power and caouts and power source.
bles can be a problem. The unit
Try to select one that will cover should be able to operate directly
the majority of signals in use at the from the battery in the vehicle, and
By Pat Finnegan
26
with appropriate cable adaptors to
attach to the battery easily.
Calibration
communications receiver will
be adequate for calibration of the
counter against WWV. You will
need to get a zero beat between
the counter reference oscillator and
WWV. It is not possible to measure
the frequency of WWV direct,
because the local oscillator in the
receiver (almost all are superhets)
will be the predominant signal.
Couple the calibrating output of
the counter to the antenna terminals of the receiver (after you have
tuned in a good strong WWV
signal). Couple only enough to get a
good beat with WWV -not override
it. If there is a tone heard, the
counter is off and needs to be adjusted. Make a careful adjustment
so the beat note (or no sound) is
right in the center of beat. If the
receiver dial is off, use the BFO in
the receiver to get a beat with the
counter signal. Remove the counter
signal, and WWV will be right
there or very close. Also, make the
final calibration during a period
when WWV is not sending tone or
A
voice.
Operation
Observe the maximum input level
specs so that high level signals will
not damage the input circuitry of
the instrument. This is important
not only in regular measurements,
but especially when doing maintenance or troubleshooting equipment
when the pickup loop is close to
coils or circuitry inside the transmitter. There may be very high RF
signal levels, or high DC voltages
BROADCAST ENGINEERING
www.americanradiohistory.com
AKAI
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The lightweight, two piece, one -man operation
that isn't a pain in the back
-or anyplace else.
comforts due to excessive
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a
2139
For More Details Circle
E.
AKAI.
Del Amo Blvd
.
Compton. Ca 90220
(20) on Reply Card
December, 1975
27
www.americanradiohistory.com
WWV
ZERO BEAT
O
7
0 0 0 0 0
cm
COW.
RECEIVER
F
IIlll
CALIBRATION
I
NPUT
o-
+2 kHz
-2 kHz
I
COUNTER
OSCILLOSCOPE
(OPTIONAU
Fig. 2a The setup for calibration against WWV. Listen for
a zerobeat in the phones. The scope also can be used to
detect a more exact null.
may arc to the probe. This could
Measuring Carriers
Always follow the instruction
manual of the instrument for the
first measurements. It won't be
long, however, until you develop
your own procedures. That is, you
13.586 kHz
FM
ZERO BEAT
INO TONEI
BEAT TONE
-
Fig. 2B When the counter frequency is above or below
WWV, a beat tone will be heard. The objective is zero
tone in the center.
will discover the best locations for
damage the unit and zap the samples of the different transmitoperator!
Couple only enough signal to the
counter to allow all the numbers in
the readouts to remain stationary.
The input required is usually somewhere around 100 to 200 millivolts
of signal. Be careful when coupling
to broadcast transmitters, especially to RF cables that carry signal
to modulation or old style frequency monitors. There can be 10
to 20 volts RMS of signal in the
cable.
BEAT TONE
ters you must measure. The FM
transmitter can best be measured
when there is no modulation, unless
your instrument has some storage
and averaging capability. But there
are usually some pauses in modulation, or you can do it after sign off.
The FCC Rules require a different logging entry than was done
in former years. Now, you must log
evident, once the counter is available. The following are just a few of
these where accurate frequency
measurement is important.
Calibration of the FM modulation
monitor is often done by use of a
communications receiver to observe
the nulls in the carrier while
modulating with a specific audio
tone. The accuracy of the calibration depends upon the accuracy of
the audio signal. But very few audio
the actual measured frequency generators have a dial that accurather than difference from as- rate, and besides, the odd -ball
signed. For example, your AM is figures fall between dial markings
assigned 1390 kHz, but is now that require 'eyeball' interpretation.
operating 2 Hz low. The counter The counter can measure the audio
will measure the carrier as 1389.998 out of the generator, so you can set
kHz. This is the figure to log.
it exactly. For example, the audio
signal required for 100% modulation (75 kHz deviation) is 13.586
Other Uses
Many other uses will soon be self kHz (for the second null). Couple
the output of the generator to the
system as is normal, but also couple
this signal to the counter. Leave the
counter coupled while the calibration is taking place so that you
know the audio is exactly what it is
supposed to be.
TRANSMITTER
Mobile Units
AUDIO GENERATOR
COMM.
RECEIVER
FM
3
s
8
6
MODULATION
MONITOR
Mobile transmitters can best be
checked for frequency when they
are on the bench for repairs. If
maintenance must be done on the
bench, make it a practice to run a
frequency check. When working
FREQUENCY COUNTER
2ND CARRIER NULL
Fig. 3 Setup for calibration of FM modulation monitor. Measure the audio frequency so that it is exact.
into a dummy load, you may need
to couple the counter near the
output circuitry to get enough
signal pickup.
In the vehicle, don't attach the
pickup loop to the antenna itself.
BROADCAST ENGINEERING
28
www.americanradiohistory.com
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enabling the transmitter to achieve an overall
efficiency greater than 60% -power line to antenna.
This efficiency is attained without the use of large iron
core components.
An EIMAC 4CX35000C is used in the class C
amplifier, with a second 4CX35000C as the pulse
modulator. Two EIMAC 4CX1500As are employed as
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For information about applying the most
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Telephone (415) 592 -1221. Or
NIC
contact any of the more than 30
Varian /EIMAC Electron Device
division
Group Sales Offices throughout
varian
the world.
December, 1975
For More
Details Circle (21) on Reply Card
'Pulse Duration Modulation
29
Place it in a spot that will give a
suitable pickup, and preferably
without holding it by hand. Body
movements can affect the signal
pickup and, in turn, the measurements.
Multiplier Stages
Most high frequency transmitters
have many multiplier stages to
bump the crystal frequency up to
the carrier frequency. When major
changes are done, such as changing
channel or replacing a transformer,
the counter can be very helpful in
indicating that a multiplier is tuned Fig. 4 Use tight coupling to the secondary of the RF transformer in a multiplier
circuit.
to the correct multiplication rate.
The normal transmitter metering
is used for tuning purposes (and frequency selection to the counter.
oscillate at all, or you may not be
power stages protected from lack
able to trim it back to the correct
Crystal Quits
of proper drive), but often there can
frequency. The counter can tell you
be several tuning points at which
The counter can be coupled close both these effects. You read all
the meter will peak. You probably to the crystal holder or its termi- zeros if the oscillator is not oscillathave to couple very close to the nals. If the crystal has no output, ing, and if all the meter indications
particular circuit since the counter the counter will read zero. Crystals seem normal and the oscillator is
will lock onto the predominant will have an aging factor. That is, oscillating, the counter will tell you
signal. Use the regular meter for over a long period of time, they will if it is on the correct frequency.
peak indication and then the change their resonant frequency.
Filters & Traps
counter to make sure that is the The same is true of the components
Television receivers, communicacorrect frequency. Some counters in the circuit itself. When all these
do provide various tuned pickup factors age enough and drift far tions receivers, and similar test
loops that can give some degree of enough, the oscillator may not instruments that contain many
(Continued on page 49)
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For More
(46) on Reply Card
Details Circle (47) on Reply Card
BROADCAST ENGINEERING
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.
For More Details Circle
(16) on Reply Card
A
B
1 Detecting amplifier crossover distortion with 10 kHz triangle wave.
(A)
Clean input (top), output notches (bottom). (B) Clean input (top), clean output
Fig.
(bottom).
Let's put function
Generators to the test
How many BE readers are familiar with the function generator and
what it can do as a general purpose
signal source? Well, as a matter of
fact, the function generator is one
of the most useful tools you could
ever hope to have around the station shop.
This article, being somewhat of a
departure from my past BE efforts,
will outline a variety of function
generator uses of value to the station engineer.
What's A
Function Generator?
A function generator is simply a
signal generator which generates
the waveforms (or functions, if you
will) of sine wave, square wave and
triangle wave. These three waveforms may be considered as a minimum, and many of the devices
available include modifications or
extension of performance which
allow generation of sawtooth and
pulse waveforms as well. Even more
sophisticated units allow AM or
FM modulation, although all of
these ramifications will not be covered here. What we're trying to do
is first get a handle on what a function generator can do, in general.
Then we can progress to bigger and
better things.
Generally speaking, function generators have a frequency range
which is usually much broader than
By Walt Jung
Function Generator
Characteristics
One 01 the keys to maximum
utility in using a function generator
lies in understanding its pro's and
cons. There are things it can do
well, and some that it can't. Since,
by its very nature, a function genertor is a universal type of signal
the waveform, without any of the
miseries of lamp or AGC bounce
we've all seen at one time or another in a sine wave oscillator.
It's not unusual to see a function
generator output stable within millivolts over a band. This can be a
decided advantage if you're checking that input level every time you
change frequency.
On the minus side, sine waves
from a function generator will almost always have a greater distortion content than a standard RC
oscillator. This is because of the
waveform synthesis method of generation used. Actual numbers will
vary from one unit to another, but
THD will usually be in the 1 to 3%
range. Even the best units do not
get much below 1 %, and 0.5% is
relatively rare.
source, it will in most cases be overshadowed performance -wise by a
generator which is specifically designed for a certain application.
There are several aspects of this
which should be appreciated, so
let's take them one at a time.
As a sine wave source, the advantage of a function generator
over a classical RC (or LC) oscillator is in amplitude flatness. The
sine wave in a function generator
created from a triangle wave, the
peak limits of which are regulated
in amplitude by precision comparison. This imparts a "solidness" to
Further complicating the picture
the fact that the sine wave THD
may also vary with where you actually are operating on a given range,
with best performance usually at
the higher end of a -100 or -10
span. for instance. And, as you get
up to 100 KHz or more, THD rises
in general, due to circuit limitations.
Another aspect of performance is
frequency accuracy and stability.
Both of these are not as good as a
typical sine wave or LC oscillator,
because of the basic method used
to establish frequency. There are
the audio spectrum, for instance
Hz or lower to 1 MHz.
from
Others go further (both up and
down), but at higher cost of course.
With this kind of range then, it is
not only suitable as an audio
source, but as a general purpose
clock for logic use, or even video
work. Thus there is the connotation
that a function generator is a universal signal source, so the subtitle
which heads this article.
1
is
1
1
BROADCAST ENGINEERING
32
www.americanradiohistory.com
,,
1
1
%WWI
II11
01M
111111/1
,
Fig. 2 Checking clipping and overload
recovery time. Full power, undistorted
20 kHz triangle wave (lower level
trace); clipped triangle with fast recovery. Scales are 20V /cm vertical, 10
us /cm horizontal.
RCA TK-76:
not specifically designed for that
function. So while it can be bettered in almost any of its individual
performance parameters, the function generator's beauty lies in its
utility. Where else can you find a
single instrument which produces
such a variety of waveforms, over
such a broad range, with such
economy?
The latter point is a good one, of
course: The value of having three
or more instruments in one. The
function generator has
a
the TV camera with
film camera freedom.
definite
the arsenal of a well equipped shop; and once you find
out how handy it can be. I'm sure
you'll agree.
place
in
Function Generator Uses
just more variables which can drift
to cause instability, and precise
tracking of dial calibration means
very close control of tolerances,
and /or trimming. So, don't expect
a function generator dial reading to
be gospel. If the precise frequency
is important. it's best to use a
counter to be sure. And, don't
count on the exacting calibrations
of an RF generator, nor it's
resolution of tuning. Tuning accuracy or resolution is usually on
the order of a kw percent, and this
too can vary as to where you are on
the dial.
Fidelity of the triangle and
square waveforms can be quite
good, the most noticeable deterioration occurring at high frequencies;
100 KHz or more. In this region,
triangle amplitude may vary and
square waves become rounded due
to risetime limitations. Also, the
degree of symmetry may depart
from the 50% of an ideal waveform.
This shift of symmetry is one major
cause of the above-mentioned sine
wave distortion.
If the picture by now sounds not
so rosy, don't be too hasty to judge
the function generator as second
rate. The comments above are
intended to give some perspective
against types of signal sources
which may be familiar. However,
those mentioned are specialized instruments and specialized instruments optimized in one regard can
always outperform a type which is
The following are but a kw uses
Of a function generator illustrated
(where possible) by actual waveform
photos using the Heath IG -1271 as
source.
Crossover distortion in an audio
one of the most
obnoxious forms of distortion to the
ear. Usually caused by insufficient
bias in the output stage, it can be
spotted. measurement -wise, by excessive low level IM. But, a quicker
way is to examine the output of an
amplifier operating into its rated
load while driven from a low level
(about 2 -5 volts p -p) 10 kHz triangle wave. If you've got crossover
distortion, it will show up as an
abrupt discontinuity in the linear
rise and fall of the triangle. A gross
example is shown in Figure la; a
more subtle form might be slight
glitches where the wave goes
through zero. The remedy is of
course, the correct bias adjustment,
illustrated by Figure lb.
Another excellent use for the
triangle wave is in checking the
power output of an amplifier and
amplifier
is
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So one person can do the job of a
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There are more desirable features
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sync generator with gen -lock, automatic iris and white balance, horizontal and vertical aperture correction,
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The TK -76 angle on value is new,
too: under $35,000.
Place your order now for 1976
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Camden, N.J. 08102.
its overload recovery time. In
Figure 2, the output level is raised
until the sharp tip of the triangle
becomes compressed, indicating
clipping. This is much easier to
discern than with a sine wave which
is (by contrast) flat on top. If this
test is run at a high frequency, say
IO or 20 kHz, the overload recovery
of the amplifier can be measured.
The more quickly and cleanly an
amplifier recovers from overload,
the better will be its sound. The
Ren
For More Details Circle (22) on Reply Card
December, 1975
33
www.americanradiohistory.com
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For More
34
Memphis, Tenn. 38104.901/276-6338
Details Circle (23) on Reply Card
BROADCAST ENGINEERING
RCA TK-76:
the TV camera with
film camera freedom.
ippout
A
B
Checking risetime of medium power amplifier with 10 kHz square wave.
(A) 3 us risetime shows exponential rise. (B) Longer, linear risetime is slew limited. Scales are 5V /cm vertical, 2 us /cm horizontal.
Fig.
3
example shown is a commercial 200
watt per channel unit driven to
clipping at 20 kHz in one trace, the
other just below clipping.
Square wave testing tells a great
deal about the frequency response
characteristics of
a
transmission
This is true, because to
reproduce a square wave faithfully,
an amplifier must have both wide
bandwidth and low phase shift, and
both of these far in excess of the
working range. Thus, a square wave
response check tells you a great
deal about the quality of a system
virtually instantaneously. You must,
of course, use a high quality source
(free from tilt, and with fast rise
and fall times) in the testing, as
well as a wide bandwidth scope.
Several examples of this type of use
follow.
An audio power amplifier can,
and often does, have two different
bandwidths. One of these is its
power bandwidth, or large signal
frequency response. The other is
the small signal frequency response,
taken at a lower level, typically
watt.
around
Figure 3a illustrates the output of
an amplifier driven to a medium
level with a 10 kHz square wave.
Under these conditions, this particular amplifier is operating essentially at its small signal bandwidth,
and the measured rise (or fall) time
will be related to its small signal
frequency response. The two are
related by
system.
1
Bandwidth =
0.35
Risetime
In the example illustrated, the
bandwidth would be over 100 kHz.
This relationship will hold for any
system where the rolloff is 6dB per
octave. Obviously then, this is a
faster method of bandwidth measurement than plotting the frequency 'response. To be sure that
the risetime being measured is truly
small signal bandwidth limited,
watch for the typical exponential
rise of an RC time constant, as
shown.
As the power level is raised, the
amplifier's output will usually become limited by its slewing rate, or
output rate of change for large
signals. In 3b, an example of slew
rate limited risetime is shown. This
case happens to be only slightly
longer. but you can note the
risetime is linear or ramp -like, a
characteristic of slew limited operation. This "ramping" is the visual
clue that the amplifier is being
driven into slew limiting. In this
example, the slew rate is about
4V /uS.
Slew rate, if inadequate, can
cause a forni of distortion as
irritating
as
UNDER
You can pay a lot more for a lot less
color TV camera.
For instance, you won't find a shock mounted optical system in any other
portable. At any price.
In the TK -76, you will find fast turn-on,
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The TK-76's film camera freedom lets
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Never has a camera of this quality
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crossover problems.
The general term for it is transient
intermodulation distortion, or TIM.
It is caused by the fact that the
amplifier is actually in an open
loop state during the slewing interval and consequently cannot amplify any detailed components of
the input waveform. Therefore, the
intervals of slewing actually cause
momentary loss of input- output
signal transfer (like crossover distortion, where the output stage is
momentarily oft). So, it is hardly
any revelation that it sounds bad.
RC/1
For More
December. 1975
Details Circle (22) on Reply Card
35
Once you've become familiar
with the information a square wave
test can give you, you can then in
turn apply it to your equipment as
very quick maintenance check.
As one further example, take the
case of an equalizer, a device which
a
purposely introduces frequency
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response variations into an audio
channel. If you wanted to test one
out by the traditional sine wave
method. it could take hours, particularly it' it is a multi knob version.
However, you can quite quickly give
it a qualitative check with an input
square wave. Figure 4 shows the
output response from a tunable
reciprocal equalizer, with a 1 kHz
square wave as an input.
n 4a the equalizer is in the
circuit, but adjusted for a tlat
response. Note that the bottom
output trace is barely distinguishable from the input, indicating
truly teat response.
4b illustrates 15 dB of boost
applied. with the equalizer peaked
at I kHz. Therefore, the output
shows a large amplitude sine wave
(the fundamental) plus the basic
square wave (the stepped portion).
The bottom scale factor is 5 times
that of the top, illustrating the increase in sine wave level.
4C shows the same frequency
setting, but with 15 dB of cut
applied at I kHz, greatly reducing
the fundamental, and leaving the
odd harmonics.
These equalizer responses are, of
course, somewhat specific examples,
but they should show what square
wave testing can quickly tell you.
Your actual responses will vary,
particularly if transformer coupled
units are being observed, or AC
coupling is used. However, once you
familiarize yourself with your own
general pattern, you can quickly
spot and isolate problems. And,
you'll be amazed how quickly!
Above there was also some
I
OVER 50 MODELS OF TAPE
CARTRIDGE MACHINES
ALSO AUDIO CONSOLES
AND STUDIO ACCESSORIES
1
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ELECTRONICS, INC.
--
A FILMWAYS COMPANY
-
8810 BROOKVILLE ROAD
SILVER SPRING, MD. 20910
PHONE 301- 588 -4983
For More Details Circle
A
Additional Reading
I) Middleton. R.G.. "Know Your
Square-Wave and Pulse Generators"- Howard W. Sams
2) Middleton. R.G.. "101 Ways to
Use Your Square -Wave and
Pulse Generators " -Howard W.
Sauts
3)
Trentaine. H.M.. "Audio Cyclopedia"- Howard W. Sauts
(24) on Reply Card
B
.omigium
,11111
11111111111111
C
Fig. 4 Checking variable equalizer performance with 1 kHz square wave.
(A) Input (top) /output (bottom) A/B
comparison with controls flat. (B) Input (top) /output (bottom) with 1 kHz
peak. (C) input (top) /output (bottom)
with 1 kHz dip.
discussion on sine wave testing for
frequency response. When this type
of test must be done, it can be
greatly speeded up, if a swept
function generator is available. The
theory is the same as sweeping RF
or IF stages; just slow everything
down to audio rates. Then you can
see your whole frequency response
right on the scope face!
This article could go on with
further examples. but space does
not permit it in this installment. I
hope your enthusiasm has been
tickled towards some new tricks in
testing methods, perhaps you can
think of further variations and
other uses for the function generator. It' so, let us know so we can
share them with BE readers.
BROADCAST ENGINEERING
36
www.americanradiohistory.com
(Continued from page 25)
would be distortion due to flattening of the positive peaks as shown
in Fig. 5(b). To compensate for this
and other nonlinearities of the
system (and to increase efficiency),
a
predistorted amplitude -modulated
RF signal is introduced at the
control grid of the PA. Overall
rectified RF feedback is utilized to
further reduce distortion and maintain Ilat response.
Both PA's are operated class C,
with resultant high amplifier efficiency. As there are no other high
power stages. overall efficiency is
also high.
The Modified Doherty
The Doherty amplifier (2) also
relies upon the interaction of the
outputs of two RF amplifiers for its
operation. In this case the inter action is impedance modulation.
Consider the battery and resistor
in Fig. 6(a). The current drawn
from the battery is described simply
by
=E
R
If a second battery of the same
voltage is added in parallel with the
circuit, the current through the
resistor will remain the same. However. the current drawn from the
first battery will be only half its
original value; or
=E
2R
The apparent load seen by the
is now 2R. When the
current was halved, the power output of the battery was also reduced
by half. The introduction of additional power in the circuit from an
external source has increased the
apparent load resistance of the first
battery.
Now substitute for the batteries
in the circuit of Fig. 6(a), the
vacuum tubes in Fig. 6(b). Assigning fixed values to the voltages
applied to the tube on the left, it
will be possible to control its power
output by varying the grid voltage
of the right -hand tube. Increasing
the power delivered by the right hand tube will cause the apparent
load resistance seen by the left hand tube to increase, causing the
left -hand tube's output to decrease.
This is an example of impedance
modulation.
battery
Now insert a one- quarter -wavelength section of coaxial line between the left -hand tube and the
load resistance as shown in Fig. 7.
Such a section of line, known as a
quarter -wave transformer, has the
ability to invert impedances according to the relationship
Zo
= vZin
RCA TK -76:
the TV camera with
film camera freedom.
x Zout
where Z0 is the characteristic
impedance of the line. This pro-
=
perty can be seen more clearly by
rewriting the equation in the form
2
Zout
Zin
constant, the
output impedance increases inBecause
Z_0
is a
versely with the input impedance.
This reverses the original relationship between the power in the
tubes. Increasing the power supplied by the right -hand tube in-
creases the apparent value of
Rload However, viewed through
the impedance inverter, this appears
as a decrease in load impedance to
the left -hand tube, causing it to
deliver more power. Under this
arrangement, an increase in the
power delivered by one tube will
cause an increase in the power
delivered by the other tube. This
property is used to create positive
peak modulation in the Doherty
amplifier.
In the Doherty, the left -hand
tube as we have described it is
referred to as the "carrier" tube;
the right -hand tube, the "peak"
tube. During operation, the static
bias of the carrier tube is at cutoff,
or class B service. The peak tube is
biased well past cutoff, or class C
service. Under carrier conditions,
sufficient excitation is applied to
the grids to drive the carrier tube
just to the point of saturation, or
the point where any further increase in grid drive will not produce
any further increase in its output.
The peak tube, because of its
higher negative bias, is just below
the point of conduction.
Increasing the grid drive past
carrier condition will cause the
peak tube to conduct, adding its
power to the output, and also
causing the output of the carrier
tube to increase. Note that the
increase in output of the carrier
tube is the result of impedance
modulation of its load and not
directly because of the increased
grid drive to the peak tube.
(Continued on page 56)
December, 1975
ONE-MAN
NEWS.
Even a one -man crew can get news fast
with a TIC -76 portable color camera.
Aim -and -shoot automatic features
deliver film camera quality even in low
light. Instant warm-up puts you on -air
or on tape just seconds after you're on
the scene.
There's no cumbersome backpack or
control unit to hold your reporter back
from the action. The 19- pound, selfcontained TK-76 is powered by a 6-pound
battery belt or a car's 12v. DC cigarette
lighter.
The M -76 is great for documentaries
and profitable local spot commercials,
for specialized sports and studio
assignments, too.
Best of all, it's all yours for less
than $35,000.
The list of orders is growing, so place
yours now and be way ahead in '76.
See your RCA Representative, or write
RCA Camera, Building 2- 2, Dept. A3,
Camden, NJ 08102.
For More Details Circle
(22) on Reply Card
37
www.americanradiohistory.com
o
5
10
>
V,
15
20
25
5
2
20
10
50
FREQUENCY IN kHz
Fig.
1
Frequency response of
a 19
kHz notch circuit.
Just How Important
Is Transient Response?
Part
1
of
a 2 -part
series
By Dennis Ciapura
BE Audio Editor and Director of
Engineering, WLAK -FM, Chicago.
While audiophiles often criticize
FM broadcasting as being something less than state -of- the -art, a
growing number of broadcast engineers are looking at their broadcast
systems as musical instruments
rather than simple communications
networks.
Last year when BE ran some
articles on I.M. distortion, there
was enthusiastic response from
many engineers, indicating that
people in the industry are eager to
look beyond the usual frequency
response and harmonic distortion
tests for ways to improve the audio
fidelity of their FM facilities.
A few years ago, much was said
and published in hi -ti circles about
transient response in audio systems
and most experts agree that systems
with better transient response reproduce music more accurately.
Most test reports on stereo gear for
the consumer include square wave
response data. The average home
stereo amplifier today is quite good
in this respect because the advent
of transformerless solid state circuitry has enabled design engineers
to evolve inexpensive amplifiers
with excellent bandwidth.
Very little attention has been given
to transient response in broadcast
systems, however, and this is an
area where improvements can be
made. The studio end of the system is relatively easy to handle,
because at that stage of the game,
we are dealing with audio only
where good quality equipment and
transformers can deliver very good
square wave response. FM stereo
signal generation is another story.
Some transmitter design engineers
feel that the 19 kHz pilot should be
protected by notch filters in the
audio to prevent musical harmonics, and possibly distortion
components.
from
interfering.
There is also the 38 kHz spectrum
to protect, as well as the S.C.A.
signals. Although there is some
question as to whether there is
really any energy of sufficient
amplitude above 15 kHz to cause
any interference. even to the 19
kHz pilot. the fact remains that
many transmitters do have some
sort of filtering installed.
Because 19 kHz notch and 15 kHz
low pass filters are very common,
we decided to see just how much of
an effect these circuits have on a
square wave input. Part
of this
series will deal with the electronic
results of this filtering and in Part
2 we'll take a listen to the audible
1
results.
Some
manufacturers' feel
so
strongly that the pilot and subcarriers should be protected that they
employ 15 kHz low -pass filters in
the input circuitry of their stereo
generators to prevent anything at
all from getting outside the 15 kHz
bandwidth specified by the FCC. At
the sanie time, some other designers, Sparta Electronics for one, feel
that transient response should be
optimized and see no need for the
15 and 19 kHz filters because they
feel that there just is not enough
energy above 16 or 17 kHz to make
the filters necessary. C.C.A. Electror.ics also subscribes to the wideBROADCAST ENGINEERING
38
www.americanradiohistory.com
The
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For complete information, contact Electrohome Limited at one
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ELECTROHOME
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For More Details Circle
Norway
Philippines
Portugal
South Africa
Spain
Sweden
Switzerland
Thailand
United States
United Kingdom
Venezuela
West Germany
(25) on Reply Card
39
December, 1975
www.americanradiohistory.com
band theory in the new C.C.A.
SG I E stereo generator.
In the case of C.C.A. stereo
generators, it is interesting to note
that the previous C.C.A. stereo
generator did employ both 15 kHz
low pass and a very sharp 19 kHz
notch in a single Torotel filter
network at the input of each audio
channel. Then a direct reversal in
design philosophy took place.
Where the older C.C.A. units
chopped the audio off at 16 kHz,
the new generators are flat to 53
kHz.
Harris Broadcast Products (Gates
Radio) is firmly committed to
protecting the 19 kHz pilot, be-
cause their engineers feel that there
is sufficient energy in the 19 kHz
region. with highly processed audio
inputs. Harris engineers feel that
the 19 kHz notch is not audible
and its presence forestalls interference in the stereo demodulators
which regenerate the subcarrier by
either doubling the pilot or synchronizing an oscillator to it.
The Harris TE-3 exciter uses the
19 kHz notch filter only and does
not employ a 15 kHz low pass
function. Also, since the notch
filters in the TE-3 are only about
25 to 30 dB deep, the Harris design
can be considered a mild alteration
of the wideband approach.
0
result in overmodulation. Obviously. normal audio will not
5
produce the same effect unless the
program material itself is clipped.
Rock operators find that the
program material itself is often
processed enough to make the
overshoot a problem, even if the
station's compression level is moderate. The wideband advocates say
that their systems offer inherently
superior performance in this respect
and are quick to point to the higher
modulation level that can be
achieved.
10
15
á
-25
30
-35
60dß
19kHz NOTCH
ao
Looking At
Both Sides
To better understand both sides of
50
15
10
5
2
FREQUENCY IN kHz
Fig.
2
The Moseley and Moseley/R.C.A.
stereo generators use a low pass
function with a very sharp 19 kHz
notch.
While there may be a difference of
opinion as to how audible the
filtering may or may not be, the
result of the 2 dB overshoot on
modulation control cannot be disputed. Stations that feed highly
compressed audio into a transmitter
with the 19 kHz notch filter will find
that the peak modulation level will
be about two dB higher than
expected because of this overshoot.
Conversely, the use of the 19 kHz
filter results in about a two dB loss
of modulation capability, if the
input is highly processed and
clipped.
Program limiters that employ clippers which allow substantial square
wave output to be fed to the transmitter can keep the filters excited
for sufficiently long intervals to
Frequency response of
a 15
kHz low pass filter with 19 kHz notch.
3^+i
18D61
-e
.N-
PULSE INPUT
19
VI
kHz NOTCH FILTER
NTO
PvIDEBAND
ISOLATION
A'.1PLIFIER
o V2
DUAL TRACE
SCOPE
the controversy. it is necessary to
take a closer look at all of the
factors involved.
First of all. you have to appreciate
the fact that pre- recorded musical
program material usually contains
very little energy above 12 kHz,
which lends credibility to the wide band theorists who say that there
isn't enough energy left in the 19
kHz pilot region to cause any malfunctioning of the receiver's demodulator circuitry. But, if this is true,
how would we find any fast rise
time signal components in that
program material that would benefitfronl frequency response beyond
the normal audible range? If,
Fig. 3 This is a simplified diagram of a test setup to check the affect of 19 kHz
notch and 15 kHz low pass filters on transient response.
40
however, the 75 usec. pre- emphasis
curve is allowed to continue unat-
tenuated out past
15
kHz and right
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Main Frame
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Modules 2 in /8 out
$135 ea.
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(tone stop only)
ACL-60T /E
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(Blank tape loader)
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blank tape)
$375
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For More Details Circle
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RAMKO RESEARCH
(27) on Reply Card
December, 1975
41
www.americanradiohistory.com
up to 19 kHz, will this degree of
high frequency boost bring the
hypersonic components up to a
high enough level to compete with
the stereo pilot?
To accurately view the effect of
the various response shaping cir-
cuits in the transmitter, one must
consider the transmitter and receiver to be a closed loop: a single
system with an overall response
characteristic. Assuming that the
transmitter and receiver complimentary 75 usec. pre and de-
emphasis alone would cause some
rounding. This is the situation that
the wideband folks try to attain.
If we want to take a look at the
spectral distribution of the program
material, the same considerations
apply, except that the 19 kHz pilot
is processed before the receiver
de- emphasis circuits, so, the de-
Row A
Row B
modulator must work with the
pre -emphasized audio.
Stereo generators with a moderate
19 kHz notch have just about
enough attenuation to make up for
the pre- emphasis and bring the
program peaks back down to their
original amplitude. The units with
very sharp 50 to 60 dB notches
cancel the pre-emphasis and yield
another 20 to 30 DB of 19 kHz
rejections to boot. The sharper
filters exhibit more waveform distortion with pulse inputs, however,
so we begin to see where we have
opened up a real can of worms.
1.
1000 hz
2.
2500 hz
Protect the Pilot?
Should we protect the pilot? If so,
should we simply protect it from
the pre- emphasis effect on hypersonic components or should we go
all the way and completely clean up
our act at 19 kHz? If we do
introduce some filtering, what will
its audible effects be, and if we
don't, what will the audible results
be?
Then there's the question of the
modulation robbing overshoot. If
the pilot must be protected, one of
two things must be done: either
great care must be taken to see that
only clean audio with as little
waveform clipping as possible is fed
3.
5000 hz
into the system, or else some
4.
7500 hz
'TT
method of notching 19 kHz without
producing an overshoot with an
input at the third sub -harmonic frequency must be found. Another
alternative would be to allow for
the overshoot and adjust the station's modulation limit accordingly.
Stations that do not employ a
great deal of audio processing
Fig. 4. These dual trace photos illustrate the waveform distortion that can be
expected from each type of filter circuit. In each case, the top trace is the
input signal and the bottom trace is filter output. Row "A" is for the 19 KHZ
notch circuit and row "B" is for the 15 KHZ low pass filter which also
includes a very sharp 19 KHZ notch. Input frequencies are as follows: 1.
1000 hz, 2. 2500 hz, 3. 5000 hz and 4. 7500 hz. The higher frequency traces
have been expanded to the same scale as the 1000 hz traces so that
comparisons can more readily be made.
usually find the overshoot to occur
for such short time periods that it
is not a factor, with respect to
overmodulation, and are able to
run at normal levels since very little
energy will fall into the skirt area of
the notch where the phase shift can
cause an overshoot.
One must also consider how the
audio will be fed to the transmitter.
Continued on page 48
BROADCAST ENGINEERING
42
www.americanradiohistory.com
ALTEC
FAIRCHILD
692 -AA
AMPLI FIER
470
8080A
-"M--
r
19
I
5
L
mfd
20
J
22
24 VOLTS
18 VOLTS
NATI ONAL
SEMI CONDUCTOR
LM- 340 -18
VOLTAGE REGULATOR
o
120V
of
A.C.
1000
mfd
MICR OTRAN
VOLTS
M829
Fig.
1
OUT PUT
150
This is the schematic for the pink noise generator.
Thking The Drudgery
Out Of Audio Tests
By Elmo Reed
VP, Engineering,
Broadcast Div.,
Post Corporation.
A
new test instrument has
re-
cently appeared on the market that
greatly speeds up and takes the
drudgery out of audio frequency
measurements. The instrument is
the Real Time Analyzer and, when
used in conjunction with a Pink
Noise Generator, makes it possible
to check the frequency response of
amplifiers, tape machines, and
a fraction of the
time required by the conventional
point by point method using an
audio oscillator.
Although not quite as accurate as
the oscillator /VU meter method, it
is accurate enough for quick checks
telephone lines in
December, 1975
where many systems are involved
and one is interested in learning
whether there has been any varia-
tion since the last check. The
results can be obtained to an
accuracy of plus or minus one dB,
and we feel this is sufficiently
accurate for quick routine checking.
From White To Pink
The instrument we use at Post
Corporation stations is the Altec
Lansing Model 8O5OA which
is
manufactured by Hewlett Packard.
The signal source is the Altec
Lansing Model 8O8OA Pink Noise
generator. The heart of the gener43
.4111
6 ""
'
VAL
44444444
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S -15,
411)
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LPB offers a complete line of broadcast audio equipment. Call or write us for all your audio needs, from
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LPB
a
and. therefore, covers all frequencies in the audio spectrum. It has
equal energy level at all frequencies, and if viewed on the oscillo-
LPB Inc.
520 Lincoln Highway, Frazer, PA 19355
(215) 644 -1123
For More Details Circle
44
circuit for generating white
noise, or random noise, as it is
sometime called. White noise is the
sound one hears when tuning
between stations on an FM receiver.
It is generated by a reverse bias
diode and then amplified to produce a useable output level.
White noise is random in nature,
ator is
For More
(70) on Reply Card
Details Circle (29) on Reply Card
www.americanradiohistory.com
BROADCAST ENGINEERING
scope of the real time analyzer.
where the audio spectrum is broken
down into one -third octave segments, the response will show a 3
dB rise per octave. The white noise
signal is, therefore, passed through
a titter that has the reverse characteristics of thé above. i.e.. 3 dB
attenuation per octave, and comes
out of the generator as pink noise.
The presentation on the scope now
has a flat or uniform amplitude
trace across the entire audio spec-
trum. Pink noise has equal energy
within any octave or fraction
thereof.
The Altec Pink Noise Generator
did not have sufficient output to
meet our requirement, so we combined the generator, power supply
and Fairchild Model 692AA transistor amplifier into a small cabinet
as shown in the photo. We felt it
was necessary to have plus 8 dBm
at 600 ohms for feeding tape
recorders, telephone lines, line am-
plitiers, etc., and minus 50 dBm at
150 ohms for feeding low level
microphone inputs.
The diagram of the complete
Pink Noise Generator is fed
through a highpass filter to compensate For a slight rise in response
that we had at the low frequency
end of the spectrum.
From the filter it is coupled into
the Fairchild amplifier. The output
of the amplifier, with an unbalanced output. is coupled into a
rri
all new automation system from
The author using
a real time analyzer and a pink
noise generator
to speed check
the frequency response of a tape
machine.
Its here! The all -new DP -2.
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The DP -2 is available in low-boy
console with desk as shown or in
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want to know more about DP -2.
Send complete information and
I
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Systems Marketing Corporation
1005 W. Washington Street
Bloomington, Illinois 61701
Name
309 -829 -6373
Station
Hoods
Closeup of the
0rcit
tartnetarton.-
ungl
Lis
Zip
pink noise generator and the audio analyzer.
December, 1975
Address
Phone (area code).
_
75.105
For More
Details Circle (30) on Reply Card
45
600/600 ohm transformer for a balanced output and from there into
the attenuator and switch so that
the various output levels can be
obtained. The power supply is
t
.
We supply the finest prói'essional au.
a rom major equipment
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We manufacture the Multi -sync, Multilimiter, and Digitimer
We design complete broadcast audio facilities from the wall in
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PACIFIC RECORDERS AND ENGINEERING CORPORATION
11100 ROSELLE ST., SAN DIEGO, CALIFORNIA 92121
TELEPHONE (714) 453 -3255
For More Details Circle
TELEX 695008
(64) on Reply Card
Have a great day...
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conventional, with solid state voltage regulators for obtaining the two
different operating voltages.
The Display
The display device for the system
is a real time analyzer. The instrument covers the frequency range
from 40 Hz to 16 kHz. The incoming signal, after amplification is
passed on to 27 parallel band pass
filters spaced at one -third octave
intervals across the 40 Hz to 16
kHz spectrum. Detectors following
the filters then convert the ac filter
output to do levels proportional to
the rms value of the ac signals. A
scanning circuit then sequentially
connects the 27 detector outputs to
the CRT screen in terms of level
against frequency.
All 27 channels are scanned in 22
ms. A logarithmic amplifier is
interposed in each filter output to
convert the voltages to signals that
can be displayed on a db scale.
Variations of input signal level
of plus or minus 10 db for each of
the 27 channels can be read from
the scope presentation. The input
signal range varies from 3.16mv to
3.16 volts in two bands.
Rapid Response
We have found many uses for the
instruments. one of the most important being the rapid checking of the
frequency response of the audio
tape machines and the audio portion of video tape machines. In
making the check. a recording of
approximately 15 seconds is made
of pink noise and then the tape is
played back while viewing the
output on the real time analyzer.
Within just a few seconds it is
possible to ascertain whether there
deviation from the correct or
flat response.
In machines equipped with a
separate playback head and ampliis any
s
a:.
a
aMww
fier, and where the frequency
response of the playback system is
known to be correct, it is possible
to make adjustments on the record
bias and equalization while simul-
taneously recording and playing
CFI HARRIS
COMMUNICATIONS AND
HANDUNG
IO
O
For More Details Circle
back pink noise. Also, if one has a
record system with a known correct
frequency response, a few minutes
of pink noise can be recorded and
this tape then used to check the
(28) on Reply Card
BROADCAST ENGINEERING
46
www.americanradiohistory.com
frequency response of all tape play
back systems.
A cartridge
of pink noise can
be
retained and used to check playback machines at frequent intervals. In this manner it is easy to
check the condition of the playback
heads and at the same time touch
up the equalization controls if
Increase sharpness...
improve camera
sensitivity
needed.
Equalizing
Telco Lines
Another use t'or the equipment is
in the equalization of telephone
lines. We recently equalized a
non -loaded line connecting our
studio in Chippewa Falls with our
studio in Eau Claire. Wisconsin, a
distance of approximately ten miles.
With the pink noise generator
located at the sending end and with
the real time analyzer and line
equalizer at the other end, it was
possible to equalize the line in a
few minutes. Each change in the
value of resistance or capacitance in
the equalizer is noted instantaneously throughout the entire audio
spectrum and, as a result, it is possible to complete the equalization
in a fraction of the time required
by the point -by -point method using
an audio oscillator and vu meter.
We have put the equipment to
good use in fast checks of the
complete audio facilities of our TV
and radio stations. With the real
time analyzer connected to the line
output and with all of the keys on
the console placed in the "on"
position, it is possible to connect
the pink noise generator by means
of a patch cord and jack field into
each input channel in turn and
within a few seconds ascertain the
overall system response.
Post Corporation either has or is
in the process of installing remote
control operation for its television
transmitters. With the off- the-air
demodulator located at the studio,
we have checked the overall audio
system by inserting pink noise into
a microphone input at the studio
and then viewing the system response by feeding the real time
analyzer with the audio output
from the demodulator.
We feel that the system described
greatly facilitates audio frequency
response checks and results in more
frequent observation of our audio
performance, something that is
often neglected in a television
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station.
For More Details Circle
December, 1975
(31) on Reply Card
47
www.americanradiohistory.com
The new
CVS 5046
Transient Response
Continued from page 42
telco
It'
Digital
Time Base Corrector
Our quality
is easy
loops are
used,
the
response past 15 kHz will usually
fall off very rapidly, so, a square
wave over 6 or 7 kHz will begin to
be integrated into sine wave any way. If this is the case at your
facility. the whole situation is very
much simplified: no square waves
are ever going to tickle the input of
your transmitter. If the studio is
located at the transmitter site and a
direct audio hook -up is employed,
or if you are feeding a composite
signal over an S.T.L., the transmitter will see pulse inputs as sharp as
your studio equipment can pass.
The Plot
Gets Thicker
Thus far we have considered what
happens to a simple main carrier
square wave input. Now let's consider the fate of a left only input.
An input into the left channel
would require a L +R and L
generation. the L
appearing in
the suppressed carrier, 38 kHz
double sideband subcarrier. The
to see
-R
-R
Typical Vectorscope display
of VTR playback after CVS
5048 time base correction.
Gyroscopic effects, when running or turning, with portable
ENG systems, poor stability of tape, and chroma level
instability are but a few of the real world problems of video.
The CVS 504B solves these problems.
And let's look at operation and maintenance. The CVS
504B requires only front panel control in all standard
operations. Every PC board requires only seconds to
install. These are just two examples of our strict adherence
to modular design.
Fig. 5. 7500 Hz input and output for
system with flat response to 50 kHz
and a 10 dB roll -off at 100 kHz. Note
that with the exception of some slight
rounding, the waveform is intact.
Then consider the fact that CVS has delivered more than
1,200 digital TBC's. That speaks for itself.
Know what to look for when you buy a TBC? CVS
can help. Just ask. We
will send you a "TBC
Buying Guide" to
assist you in evaluating
the real world of digital
time base correction.
48
Continued on page 57
FREE
Look to the leader.
cv,
upper sideband of the subcarrier is
limited to 53 kHz (38 + 15 kHz)
and the first S.C.A. appears at 67
kHz. So. now we have the decision
of whether to use filtering to cut off
CATALOG & AUDIO APPLICATIONS
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Santa Clara. California 95050
(408) 247 -2050 Telex: 35 -2028
For More Details Circle (32) on Reply Card
for Demonstration Only Circle (69) on Reply Card
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(75) on Reply Card
BROADCAST ENGINEERING
DECEMBER. 1975
came enaneeRinG
COLOR BARS
REALLY CAN HELP
By Oliver Berliner, Ultra Audio
More than two -dozen years ago.
when cablemen were in another
business or perhaps going to school.
television was such a novelty that
people would actually sit and stare
at test -patterns (remember the tra-
ditional old Indian -head pattern
with the kHz tone accompanying
it ?). That test signal was there to
not only help the TV station test an
tune its equipment, but to (supposedly) assure the viewer that his
was working properly, and to
assist hini in setting tine -tuning,
brightness and contrast.
As sets unproved. viewers became
more experienced. and program
volume increased. such test -signals
1
all but disappeared. and are now
available only intermittently and
late at night
.
usually in the
.
.
form of staircase. colorbars or
multiburst.
But the advent of color, the
emergence of hard -to -tune UHF
stations. and the practicality of
community- antenna television have
reintroduced the
need for transmission of test signals often, or
continuously, and at convenient
hours. These test- signals could not
only inform the viewer as to
whether he's experiencing difficulty
with his TV. the cable system, or
the TV station he's watching. If the
viewer could reach the right conclusion. he could then avoid blaming
you. the cable TV operator. for
troubles not created by the cable
You can use these step and bars
generators to great advantage in
your own studio for equipment
Colorbar Tests
checkout and setup of your color
The most important single test and monochrome monitors. There
signal you can transmit today. as are available generators that prefar as your viewers are concerned. sent what is known as split-field
is colorbars.
have been in innu- colorbars. These devices display
merable homes. including those of simultaneously not only colorbars
various entertainers who are (sup- but also 1 and Q signals (these are
posedly) more critical when it "N'l'SC Standard" bars) plus a 5conies to their sets' display, and step staircase pattern. Split -field is
have been horrified to find color excellent. but offers some important
levels, phasing ("tint ''), brightness disadvantages:
and contrast all wrong.
Sadly, they seem content to live
1. These generators are quite exwith it that way; but I like to think
pensive. Separate full -field
it's because they haven't tried for
colorbars and staircase generanything better. Incidentally, one of
ators may actually total less
the gravest, yet most common.
than the cost of a single split mistakes is to let light "spill" onto
field generator.
the kinescope. This type of light
2. With all patterns created by
will reduce contrast and will affect
one device, you lose everything
colorimctry. Warn your viewers
in the event it fails.
about the liad effects of improper
viewing conditions. They'll be grate3. 'l'he staircase portion offers
ful you did. And don't forget that a
only 5 steps which are often
receiver's colorimetry changes fretoo difficult for the non-proquently. so transmissions should be
fessional to use to set his
Brightness and Contrast propdaily.
erly. "l'he 10 steps are easier to
work with (besides offering a
The Staircase
more critical test of the equipThe second -most important test
ment involved. plus the fact
signal for your viewers' purpose is
that they would be full -field).
10 -step staircase with each of the
(However, split -field is excelten steps, of course. differing in
lent for your use in checking
intensity from the adjacent two by
luminance- chrominance crossten percent. Usually, the first step
test -patterns. Y ou should really do
both.
1
is
10
IRE Units. of video (in
network.
However, test -patterns do the
effect- black),
viewer (and you) no good unless he
knows how to interpret them. There
are two ways to inform him of this
valuable service. You can enclose a
descriptive flyer with your monthly
bill. Do this twice a year. And, you
can transmit instructions that he
can see in conjunction with the
generators reverse the staircase
CE-2
the last is 100 IRE
(highest level- white). Some "step"
sequence. By the way, these devices
are correctly designated as staircase
generators or (the slang) step generators. They are sometimes incor-
rectly referred to as "stairstep"
generators. which is redundant and
wrong.
modulation.)
4.
The split -field display does not
lend itself to superimposing
instructions to the viewer over
the display. because there just
isn't room.
Other Test Signals
There are, of course, other valuable test signals, such as 2T -IBROADCAST ENGINEERING
yet
WI
the
TRUE...
PRICE
of
Croii-PuIse 8
Color MOA1tOu
HAS DROPPED
window, but these are for use by
experienced technicians and are too
sophisticated for telex iewers. Even
if your cable customers could interpret these displays. they would be
hard put to du anything about it.
anyway. For example, if they de-
Now you can convert any monitor to a cross -pulse
monitor with VACC's new $345* model CPG -1
Cross Pulse Generator. Your monitor requires no
modification. Fill out the coupon below for more
information. At the same time, ask for a free copy
of VACC's Troubleshooting Chart. This handy wall
chart has actual photos showing typical video conditions such as normal sync with and without burst,
time -base errors, overshoot, clipped sync, and many
pore. VACc's chart is a valuable aid when adjustand troubleshooting video problems using a
tected ringing in their receivers, it
would probably be impossible for a
repairman to get rid of it.
So. your best bet is to start with
an inexpensive full -field colorbars
generator. In fact. the right product
will have a chromakiller provision
so that it can generate unmodula ted bars which are, in effect. 8
non- linear shades of grey, starting
with %yhitc and ending in black. If
you go this route, here's what you
flu.
cross -pulse monitor.
If a video monitor is needed, install a VACc Electrooptical Isolator in a Sony receiver. A engineer or
electronic technician can install a model A -1 in a 12",
'5" and 17" Sony receiver in less than an hour. Model
AI -A should be installed in a KV 1711, KV1722 and all
19 inch Sony receivers. You add only one -half pound
:o your receiver and your Sony can be used as a
sigh quality monitor or retained as a reciever by
merely flipping a switch. Isolation is far superior
to heavy transformer isolated monitors and you
can connect up to 20 monitors without troublesome ground loops if all monitors have VACc isolators.
First. enclose
a semi- detailed
description of your
eolorb:n's pattern with your monthly
subscriber billings. Tell your subscribers that during certain hours
of the day you will he transmitting
colurbars on a spare channel you've
set aside for this purpose. Explain
non -technical
Z
w
r-
w
U
Figure
cc
0
CC
by popular request
NEW DEMODULATOR KIT
w
Jm
U
m
NEED AUDIO /VIDEO -OUT TO RECORD OFF -THEAIR? Order VACC's new model D1 or D1A Optical
Demodulator. Similar to, but smaller in size than the
widely used VACC Al or Al -A Optical Isolator,
VACC's new optical demodulator kit is easy to install
and has the same outstanding isolation and weight
advantages. Use model D1 for Sony's KV1201, 1203,
1212, 1214, 1500, 1511, 1710 and CKV 171 and the
Dl -A for KV1711, 1722, 1910, 1922 receivers. Yes,
you can install the Al and D1 or Al -A and D1 -A in
the same Sony receiver to have a receiver monitor demodulator. Add VACC's Cross Pulse Generator and
you can have all four functions using one CRT.
VIDEO AIDS corporation of colorado
1
112 West 4th Street, Loveland, Colorado 80537
phone (303) 667 -3301
For More Details Circle
December, 1975
www.americanradiohistory.com
(76) on Reply Card
CE-3
that by adjusting the color level and
tint controls on his receiver, the
viewer can make studio -type adjustments to his TV which will improve
picture reproduction. (Don't forget
to also discuss the previously mentioned matter of room lighting.)
Include a drawing of a TV screen
(Figure 1) with the 8 colorbars
from left to right:
WHITE- YELLOW -CYAN (blue marked.
green) -GREEN -RED -MAGENTA-
OUTLINE OF
TV SCREEN
THE FOLLOWING
I
S
A COLOR BARS
ADJUST COLOR & TINT
TEST PATTERN.
SO THAT THE COLORS APPEAR FROM
LEFT T
0 TO
R
I
GHT AS FOLLOWS:
BLUE -BLACK. Tell the viewers to
adjust both Color and Tint controls
until these colors appear in this
Explain that improper
sequence.
phasing (tint) will alter these colors
and degrade viewing pleasure.
Second. prepare 2 TV "billboards." such as those shown in
Figure 2. You'll notice that I've
shown the listing of the colors in
the lower -half of the raster (2b).
only. By printing your key- camera
titlecard in this fashion, you can
first show Billboard 2A. then Billboard 213, then switch -in the color bars. then (it' you desire) key -in the
color listing over the colorbars
themselves. This will remind the
viewer of what colors to set up for.
in rase he's forgotten or mislaid
your mailer.
After, say. two minutes of bars.
repeat Billboard 2A and 2B and the
entire procedure. After another two
minutes do it one more time and
this time leave the colorbars on for
an hour
or all day. if you wish.
The white and black bars will.
theoretically. permit contrast and
...
Figure 2a
brightness setting. But unfortunately, most viewers cannot be
to grasp this; so your
colorbars procedure should be preceded with staircase and its instructions. such as the billboard of
Figure 3. Use the presentation
format described for the colorbars.
Of course. you will have to alter the
description if you use your bars
generator. with chroma off. to
create your (non- linear) staircase
pattern. By turning your chroma
off. you avoid the problem created
by your viewers' failure to do so on
their receivers during the Brightness /Contrast -setting interval.
These test -signals will prove most
helpful to your field- service technicians both in the case of hooking up new subscribers and in the
checking of your many cable-amplifiers. Coupled with their use in your
studio, they help create an atmosphere of viewer confidence while
permitting many of your subscribers to determine for themselves the
condition of the video you're proexpected
WH ITE- YELLOW- CYAN -GREEN-
MAGENTA -RED -BLUE-BLACK
(ALTER BRIGHTNESS & CONTRAST
ONLY TO IMPROVE BLACK & WHITE)
Figure 2b
THE FOLLOWI NG TEST PATTERN
I
S
FOR
YOUR USE IN SETTING BRIGHTNESS &
CONTRAST. TURN DOWN COLOR CONTROL.
SET CONTRAST SO WHITE (FAR
RIGHT)
BAR IS BRIGHT BUT NOT "BLOOMING
SET BRI GHTNESS SO THAT BLACK (FAR
LEFT) BAR
IS JET -BLACK.
THERE ARE
El GHT SHADES OF GREY IN BETWEEN.
Figure
3
viding them along with
their
receivers' performance. Thus this
modest investment can repay you
manyfold.
CE -4
BROADCAST ENGINEERING
;Zt '
REMOTE BROADCASTING
1
1
Os C
OUTPUT
1
®
3
?
®©®
6x '44'
®,:
,
xss+it,
4.
1(..._
®
rA
0,.
,
FREQUENCY COUNTER
REMOTE SITE CONSOLE
Use Standard Telephone Line
When testing a crystal oscillator, couple close to the crystal itself. Then
you can determine the actual frequency. When some counters indicate digits are
in the overflow circuitry, the readouts will give a reading of digits after the
decimal, adding to the unit's capability.
Fig.
5
Direct Distance Dialing
'
'
(Continued from page 30)
traps and filters, require accurate
test signals to adjust them correctly.
Most signal generators do not have
accurate dials. The counter can
be picked up and mistaken
for one
from the signal generator.
Summary
'
If your
measure the signal out of the
generator and the generator can be
adjusted so that the required signal
is exactly on frequency. Leave the
counter coupled to the generator
while making the adjustments to
the traps. in case the generator is
not too stable. But with RF type
circuits in the receivers, make sure
there are no signals radiated from
the counter local oscillator that can
station has many carriers
that require measurement according to FCC Rules, you should use a
frequency counter, but the instrument must be accurate, stable and
calibrated. Once you have a counter, you'll find a bonus in its
endless uses in maintenance where
accurate frequency measurements
will help keep the equipment
operating at peak performance.
-.
'
Sel Up and Check Out in Minutes
High and Low End Frequency Compensation
with Automatic Level Control Option
Lost Line Auto Hang Up Option
Auto Pick Up on Redial Option
Up lo Six Microphone Inputs With Level Control
Option, Four Headphone Outputs With Level
Control
Output Matched For Standard Telephone Line or
Loop With Level Control. VU Meter. Built In
Telephone Line Coupler and Output For PA
Amplifier
AC DC With Battery Test Meter
Built In Telephone Dial
Options In Addition to Those Noted Include'
Carrying Case. Microphones, Headsets.
Test Tone Generator, Aux Inputs. Phono
Cartridge Input and Three Pin Connectors
STATION END CONSOLE
PULE DYNAMICS MANUÇA( lURING CORPORATION
For More Details Circle
designed for television...
Datatek
100...0
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(63) on Reply Card
TYPE D -630
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Features:
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Wide sweep range, variable up to
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Excellent linearity
Variable sweep rates from 20 sec. to
1/60 sec. Fixed rates at power line
and video field (locked) frequencies.
Manual sweep.
Sweep range set by separate start
frequency and finish frequency
controls. Sweep reversible.
Built in frequency readout,
switchable to show start, finish,
variable marker and sweep output
frequencies.
B
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Comprehensive marker facilities.
Fixed markers at 1 MHz and 5MHz
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Symmetrical marker blanking in
sweep output. Separate marker pulse
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Internal or external sweep
modulation, for applications including
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Conveniently small unit, with signal
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A. Modulated sweep, non -comp..
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B. Composite video sweep. 2- 0- 20MHz.
marker blanking at 1 MHz intervals
C. Detected non -comp. sweep variable
stop markers at 7.5 and 17 5MHz.
D. Marker pulses output. 1 MHz
intervals (5MHz intervals evident,
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For More Details Circle
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December, 1975
49
www.americanradiohistory.com
ELIMINATE
TAPE
NOISE
SBE
(Continued from page
16)
Pittston. The speaker, Mr. Oded
Ben -Doy, an engineer from RCA's
research and development lab.
spoke on the future of TV and FM
broadcasting, especially as it relates
to the use of circularly polarized
FM and TV transmitting antennas.
Mr. Ben -Dov traced the development of the broadcast transmitting
antenna from the superturnstile
state to the present. John Kowalchick (Chairman) RCA Solid State
Division. Crestwood Rd.. Mountaintop. Pennsylvania 18707. (717) 4746 761.
WITH
30 DB NOIE REDUCTION AND
10 DB EXTRA HEADROOM
With dbx Model 142 noise reduction in the rack, you can:
Nearly double the usable signal -to-noise ratio of your cartridge chain, studio
master recorder, line and program amps, full-frequency land lines, and microwave links.
Make original tapes completely free of hiss or background noise on open reel.
cartridge. or cassette format.
Duplicate tape through three or more generations without audible noise build -up.
dbx noise reduction linearly compresses audio signals by a 2:1 ratio at the front
end and produces an exact mirror image 1:2 expansion at the terminous of the
audio chain.
True RMS level sensing circuitry insures perfect encode /decode tracking
over a dynamic range well in excess of 100 dB irrespective of phase shifts in the
transmission or storage medium. There is no breathing, pumping, or other coloration of the sound with dbx noise reduction, and there are no pilot tones or calibration levels to worry about.
dbx Model 142 provides two channels of broad -band audio noise reduction in excess of 30 dB coupled with an additional 10 dB increase in headroom
for all components and lines included within the noise reduction loop.
For complete product information and list of demonstrating dbx dealers.
circle reader service number or contact:
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617/899 -8090
For More Details Circle
50
Chapter 15: New York City
Chapter 15 met October 9 at the
WQXR Presentation Theater to
hear Mr. Mark Schubin, technological consultant at the Lincoln
Center for the Performing Arts.
Mr. Schubin gave a slide presentation and spoke on new developments and the state of the art of
television as it affects both the
manufacturer and consumer. John
Lyons (Chairman) WWRL Radio.
41 -30 58th Street. Woodside. New
York 11377. (212) 335 -1600.
Chapter 36: San Diego, Calif.
The San Diego Chapter met on
October 23 at KFMB -TV8 to
participate in a program on "audio
problems and solutions and the
impossible situations we have in
commercial broadcasting." Heading
the discussion was Mr. Charles
Able who led the group in answering questions and resolving problems. Bob Boulio (Chairman) 6841
Convoy Court, San Diego. Cali .1brna 92111.
Chapter 37: Washington, D.C./
Alexandria, Va.
This new Chapter is also growing
rapidly. Their October meeting was
held at the U.S. Information
Agency in Washington, D.C., where
Mr. W. Mitchuni led members on
an extensive tour of the USIA radio
and television facilities. A business
meeting followed to discuss the
election of officers. Charles Riley
(Chairman) Tele -Color Productions.
708 N. West Street, Alexandria,
Virginia 22314. (703) 683 -3203.
(35) on Reply Card
BROADCAST ENGINEERING
MCMARTIN
PEOPLE
-E
EBS
On the 31st of December, Robert W. Sarnoff will
step down as Chairman and member of the board at
RCA. Anthony L. Conrad has been designated President and Chief Executive officer. SarnotT will receive
the Electronic Industries Association (EIA) 1976
medal of honor at a meeting to be held in March....
On the other coast, Nyal McMullin has been named
President of Consolidated Video Systems by the
board of directors. In an earlier move at CVS, Harry
Mueller was appointed Director of Manufacturing....
Datatron's President, Clyde J. Davis, announces
that Herbert Perkins has been elected a vice
president. Perkins had been general manager of the
editing systems division of Datatron....
Following a prolonged illness, George A. Sauppe,
co- founder of Spindler & Sauppe, died in his sleep at
the age of 88. Known for his "firsts" in the A -V
industry, his last major development was the first
random access slide projector....
Robert Hawkins has been appointed national sales
manager, professional products, of Sharp Electronics
Corp. Hawkins formerly worked with Sony and
General Telephone in Michigan....At TEAC Corporation of America, Allen Novick is now the national
sales director, and John Bennett is their new director
of operations....
Louis Siracusano has joined A.F. Associates as
Vice President -Sales. Siracusano was formerly a sales
engineer with Ampex....3M's board of directors has
elected two new group vice presidents. They are Allan
Huber and Allen Jacobsen. Jacobsen was elected VP
of the Tape and Allied Products Group.
Mike Snyder has joined the engineering staff of
New Jersey Public Television. He previously was with
the Kentucky Educational Television Network....Lee
Whitehurst has drawn the assignment of Technical
Director of WSM -TV, Nashville, Tenn....And as of
December 1, Stanley Mouse became head of all Cox
TWO-TONE
EMERGENCY
BROADCAST
SYSTEMS
EBS-2
Decoder -Two Tone Monitor
$ 99.50
FCC CERTIFIED
s
o
TG-2/EBS Encoder -Two Tone Generator
FCC TYPE ACCEPTED
$225.00
with
AMR -1
AM Fixed Frequency Receiver
$ 99.50
or
Broadcasting Corporation broadcast operations.
Mouse joined CBC in 1945 as promotion manager of
WHIO, Dayton....
If you have news of position changes in your
station or operation, send details to The Editor,
Broadcast Engineering, 1014 Wyandotte St., Kansas
City. Mo. 64105.
Frederick DeTurk, President of Phelps Dodge
Communications Company, has named James F.
Jennings, Jr., Executive VP, and Albert Gallick to the
post of Sales Manager....
At press time
we learned that Chuck Rockhall,
formerly regional sales manager for Sparta, has
joined Time & Frequency Technology as national
sales manager. Rockhill's first assignment will be to
promote TFT's EBS equipment... .
FMR-1
FM Fixed Frequency Receiver
$
99 50
FCC CERTIFIED
McMartin, a leader in the development of broadcast equipment
has available for IMMEDIATE DELIVERY the NEW Two Tone
Emergency Broadcast System. This system complies with all
FCC Regulations. A complete AM or FM system (EBS -2, TG2/EBS and AMR -1 or FMR-1) will cost you
only $424.00.
...
CALL or WRITE
McMartin Industries, Inc.
4500 South 76th Street
Omaha, Nebraska 68127. (402) 331 -2000 Telex 048 -485
For More Details Circle
December, 1975
www.americanradiohistory.com
(36) on Reply Card
51
r
Cartridge
PRODUCTS
tape
machines
with
innovation.
Beaucart is coming.
For More Details Circle
(37) on Reply Card
Two Tone EBS Package
McMartin Industries, Inc., can
now provide complete EBS alerting
capability for the new FCC two tone attention system which must
be in operation at all AM, FM and
TM broadcast stations by April 15,
1976.
The FCC Type- Accepted Model
TG -2 /EBS Two Tone Generator
meets the new encoder requirements in providing a minimum +8
dBm, 600 ohm output of the
required 853 and 960 Hertz tones
within
Hertz tolerance. The
tones are produced by digital logic
division of a highly -stable crystal
oscillator frequency source. Tone
transmission duration is controlled
by an automatic electronic timing
device. The TG -2 /EBS is designed
for standard 19" rack mount.
An appropriate decoding system,
conforming with the new FCC
Rules, is comprised of either the
McMartin Model AMR -1, AM; or
Model FMR -1, FM, fixed frequency
receivers used in conjunction with
the FCC -certified Model EBS -2,
Two Tone Decoder. The system is
normally in a "muted" condition.
For More Details Circle
(80) on Reply Card
Color
Disc Recorder
first "Instant Replay" color
The
disc recorder under $10,000 has been
introduced by Eigen Video, Grass
Valley, California. The magnetic disc
recorder can do jitter -free forward
and reverse slow- motion as well as
freeze- frame.
The recorder has a time capacity of
Broadcast Clarity Built -in Monitor.
TCG -1432A Character Generator,
8-page Memoryy The
Including Monitor and Memory Options...
-
TeleMation's excellent character generator
the TCG 1432A
including its optional monitor and 8 -page
memory, is now available for less than $3,200. Here
is a titler of proven performance and standard design
features meeting broadcast criteria:
A built -in matting amplifier.
A 120 -element character matrix, with shadow edging,
for exceptional clarity.
16 lines of 32 characters (14 lines within SMPTE
Safe Title Area).
A built-in RS -170 sync generator with genlock.
-
...for
less than
Versatility is assured for the
$3,200
TCG -1432A by its many plug -in
accessories and optional add -ons. Among
these, its color background generator with
custom -designed patterns, digital clock and audio tape memory coupler are now also offered at new, low
prices.
Call us for details.
TeleMation
the discovery people
Y
ATLANTA
o. BOP 1so88 SALT LAKE CITY, UTAH 88115
CHICAGO '- DALLAS
DENVER
LOS ANGELES
NEW YORK
OMAHA
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WASHINGTON, D.C.
BEIRUT, LEBANON
LONDON, ENGLAND
MEXICO CITY, ME XICO
RIO DE JANEIRO, BRASIL
SANTIAGO, CHILE
BOSTON
-
For More Details Circle
52
(38) on Reply Card
BROADCAST ENGINEERING
The dual inputs can each be used
10 seconds, twice the length of an
average football play, and a variable
range of record /play rates from 60
fields per second down to still image.
The signal to noise ration is greater
than 46dB. The recorder uses standard video inputs and the output can
he used directly in a non broadcast
application, or time -base corrected for
broadcast use. The recorder locks to
station vertical sync.
A TV studio could use the disc recorder not only for sports "Instant
Replay," but also could add animation,
time -lapse and electronic slides for
titles, commercials and station promos. Any news show could add the
"Instant Replay" effect to sports film
and tape even though the original was
shot at standard rates.
pair of 60 kW transmitters
and can be alternatively operated
with the combined 120 kW into
either half of the antenna.
This line of VHF and UHF horizontally polarized antennas is also
available for low cost on -site conversion to circular polarization.
with
-
For More Details Circle
a
HELP!
VIDEO
tension the "pulse" of your
is
Tape
video recorder /player. TENTEL has
a tension gage designed for your
application to provide a fast, accurate measurement of the tension
with the machine "in operation."
For More Details Circle (82) on Reply Card
Studio
Color Monitor
Unimedia announces a feature
loafed studio color monitor.
lie new SM7- -12 includes Full iris all Identification, A -B Electronic \ ideo Selection, Internal Lxiernal Sync Selector Switch.
Keyed Back Porch Clamp with Full
DC Restoration and Variable Aperture Control. A new set up switch
allows the user to set color threshold and grey scale tracking.
"I he SMT -12 now features front
panel doors lOr concealing secondary controls which include RGB
background adjustments and variable aperture control on the right
le. The left panel conceals horiI
I
(81) on Reply Card
UHF -VHF
Antennas
Bogner Broadcast Equipment
Corp. has Omni- directional. 120 kW
slot- director transmitting antennas
that are already in use. They incorporate a very successful feed
system that has been in the field for
three years.
TENSION PROBLEMS SHOW UP AS:
Interchangeability problems
between two or more recorder
players.
Horizontal time base instability
which causes flagging and picture
distortion.
Premature headwear and tape
wear due to high tension.
Approved by Ampex, I.V.C., and
Sony, (Great for U- Matics).
From $179. Send for additional infor
mation or call today.
TENTEL
14081377 -6588
Curtner Avenue
Campbell, California 95008
50
For More Details Circle
(39) on Reply Card
TWO NEW COX BOXES!
FROM MICHAEL COX ELECTRONICS
Derives a high quality keying signal from encoded
video using comb filter decoding techniques.
Provides an input to the external key on any video
switcher or can be used with our 150 DKM downstream keyer. With available options the 231
TYPE 231
ENCODED
CHROMA KEYER
FROM $2470.'
i
becomes a "Stand Alone ", downstream chromakeyer,
complete with it's own effects key and 5 input
vertical interval switcher for selecting chroma key
source.
The most versatile downstream keyer in the industry.
TYPE DKM150
DOWNSTREAM
KEYER
$2070.
9
no
n
Cut a key in and out of program
Dissolve a key in and out of program
Fade to black
Why not expand your video production facilities with these versatile, economical
They can be added to any system in minutes with a few BNC's.
boxes?
Distributed exclusively in North America by:
broadcast video systems ltd.
F.O.B. TORONTO, CANADA
CANADIAN F.S.T. NOT INCLUDED
1050 McNICOLL AVE.. UNIT 9, AGINCOURT, ONTARIO M1W 2L8 Tel. (416) 497 -1020
For More Details Circle
(40) on Reply Card
December, 1975
53
www.americanradiohistory.com
zontal, vertical adjustments and the
new set -up switch. Options such as
pulse cross and underscan are
accessible from behind the left side.
The SMT -12 has a new look
about it with satin pewter anodized
front panels and new extrusions
mounted on the sides of the
cabinet. Now available as an option
with the new SMT -12 are Rack
slides for case in removing the unit
`
sound
dunamics,itic.
For Detailed Information
and Prices.
46,
from the rack.
Other models in the SMT series
include 19 -inch. 17 -inch. 15 -inch
and 12 -inch yoke mount and cabinet versions as well as a 9 -inch
portable.
For More Details Circle (83) on Reply Card
Tape Tension
Meter
The control of tape tension in
The New
Master Cart
from
FIDELIPAC®
'
\L)
Guaranteed Stereo
Performance to
within 60 degrees
of 0 phase
at 12,500 Hz
,,.
\\.
...
Now Available Direct
From:
Engineered to use natural tape flow
patterns that eliminate erratic tape behavior and assure repeatability both from
cartridge to cartridge and usage to usage.
Fewer parts for simpler maintenance ...
and greater
sound
reliability.
dunamics.nc.
Post Office Box 1335
4
scanner. By manipulating the skew
control away from its detented position to maximum and minimum
conditions,
the
tension
meter
showed a range of 60 to 120 grams.
This range is quite adequate to
accommodate the nominal Sony
recommended value of 90 grams for
U- ntatic format tape tension. In
addition, there was adequate control in case a poorly recorded tape
needed to be played.
Inserted into the tape path after
the exit guide. the gauge showed a
reading of 20 grams.
The Tentelometer comes in a
small foam -lined plastic case, has a
Tel: (408) 926 -3588
Sunnyvale, CA 94088
For More
any VTR is important to the
accurate timing of recorded and
reproduced TV signals. It is particularly important in helical recorders which use a single head
scan per field. The tension differential between the record and replay
modes produced a very annoying
effect at the top of the picture
known as skew or flagging.
A very useful device to check and
maintain proper tension levels in
VTRs is made by Tentel and was
tested by B.E.'s video editor.
The unit has a large scale calibrated in grams and ounces, two
fixed and one movable pins extend
from the bottom and are long
enough to encompass all tape
widths in common use today
(quarter -inch to two inches.).
Inserted into the tape path. the
meter reads the dynamic tape tension and the fluctuations that may
be caused by mechanical defects.
Tested on an open Sony U- matic.
the Tentelometer read a steady 80
grams at the entry point of the
Details Circle (41) on Reply Card
Still the industry's MOST WANTED
4.4c/
RECORTEC, INC.
VIDEO TAPE TIMER
Bright LED display
Optional remote display
Available for all 2 -inch VTRs
Free evaluation to qualified buyers
777 PALOMAR AVE
SUNNYVALE, CA. 94086 TEL: (408) 735 -8821
For More Details Circle
54
(42)
TWX: 910 339 9367
on Reply Card
BROADCAST ENGINEERING
clear set of instructions, can be
easily calibrated, and is simple to
use. It should prove to be a handy
device for certifying proper VTR
operation for owners of any magnetic recording equipment.
For More Details Circle
(84) on Reply Card
Rugged
Headphones
Radio stations looking for really
rugged headphones will be interested in the Television Equipment Associates new Astrolite HiFi phones. available either stereo
double phone. or single side. The
headphone has a frequency response of 50- 15.000 Hz and impedance of 2(X) ohm (or, optionally
6.00( ohm).
The Astrolite stereo phone weighs
only eight ounces and, like the
range of the Astrolite headsets, is
fabricated from practically unbreakable components such as all -nylon
plastics (that won't break when you
drop them), a steel headband with
padded cover, and tinsel cable.
Astrolite otters a choice of ear enveloping cushions or ventilated
cushions which eliminate perspiration and accommodate eyeglass
frames.
For More Details Circle
to four channels.
The QT -I solves the problem of
interfacing multiple audio accessories such as outboard Dolby or
dbx noise reduction devices. graphis
equalizers. matrix (SQ. QS. RM)
and CD-4 encoders and decoders.
limiters and other signal processing
units. The Q-t -1 provides the same
flexibility expected of a hard wired
studio patchbay.
The QT -I audio switching and
patching center has 72 RCA type
top
phono jacks on the back panel
which permit the user to simultaneously connect up to four tape
recorders. plus other required accessories and leave then connected
to the rear panel of the QT -I. All
inter -connection functions may then
be conveniently performed by front
panel switching or changing patch
cords just as is done with a
permanent console patchbay.
For More Details Circle
(86) on Reply Card
(Continued on page 60)
ForTape Heads
Head for TABER
At Taber you get precision work, quality results and low price
unmatched by any other audio head manufacturer.
...
We will recondition your three head assembly ... F/T $45.00 ...
2 TRK $60.00. Three new 2 TRK heads installed and aligned in your
AG-440B for $264.00... Scully 280 at $270.00.
Ampex VTR audio is priced at only $385.00
for four new heads installed, or $110.00 for
four reconditioned heads. (Add $38.50 if
monitor post needs lapping.) RCA VTR
audio heads are available for only $475.00.
Loaner assemblies are available.
(85) on Reply Card
For heads, head for Taber
... the best
source
available.
Audio Switching
Send for free brochure.
And Patching Center
Russound /FMP, Inc., the switch box people, announce their new
portable audio patching center
which allows small studios, broadcasters. and semi -pro recordists to
connect all their accessory equipment together and to switch components for live recording, mixing,
signal processing and dubbing in
TABERManufacturing &
2081 Edison Ave,
For More
VR1200-R
I
411
;
i, .5
-3831
Details Circle (43) on Reply Card
,
VIDEO TAPE RECORDER
TR22-R
RECORTEC, INC.
R -MOD is the logical answer to your requirement
for automating existing VTRs.
The field installable modification kit upgrades your
existing VTR transport to achieve performance like
that of the newer vacuum buffered drives.
777 PALOMAR AVE. SUNNYVALE, CA. 94086
For More Details Circle
December, 1975
9457-
VR1100-R
TR7O-R
TR22
Engineering Company
Still the industry's MOST USED
VR2000-R
I
San Leandro, Ca.
TEL: (408) 735 -8821
TWX: 910 339 9367
(44) on Reply Card
55
MARTI...
Digital Air
Temperature
(Continued from page 37)
The Name to
Remember
.
RADIO
REMOTE PICKUP
150 - 450 MHZ
PARADES
SPORTS
NEWS
RECORD HOPS
COMMUNITY
EVENTS
SUPPER CLUBS
RESTAURANTS
RELIGIOUS
SPECIAL EVENTS
RPU
Transmitter
HOUSES
OPEN
WATER
SALES
CARNIVALS
FAIRS
$975.00 (150 MHZ)
$1145.00 (450 MHZ)
All Solid -State
Direct FM Modulator
Broadcast Quality
Continuous Duty
Four Audio Mixing Channels
Plug -in Modu-
FEATURES:
lar Construction
Meters
-
I.F. Crystal Filter
Taut Band
Radio Remote Pickup Equipment is versatile,
dependable and an entree to profitable radio
broadcasting. That is the acclaim given to Marti
RPU Equipment by American Radio Broadcasters.
"How did we ever operate a radio station without it ? ", is the comment most often heard after
equipment has been purchased and put into
service.
progressive minded, cdmmunity spirited
broadcaster, can find many uses for Remote
Pickup Equipment. He will do many more remotes than he is presently doing, simply because the equipment is available at a moment's
notice. To coin an old cliché, "It doesn't cost
it pays."
The
-
Add Color to
Your
!1l
Remotes...
PORTABLE
BROADCAST
REMOTE PICKUP
TRANSMITTER
Model RPT -1
Portable operation on internal rechargeable nickel-cadmium battery. Total weight
only 51/4 lbs. All Solid -State Built -in battery
charger
Dual frequency operation (One crystal
included)
Meter indicates battery condition
Whip antenna mounted diand modulation
rectly on unit
Broadcast -quality Compressor/
Limiter handles toughest remote pickup conditions
Two microphone inputs (one push-totalk) and one Hi -Level input each with individual mixing gain control
FEATURES:
COMPLETE LINE OF ACCESSORIES AVAILABLE
Xe. 661
similar means.
The resulting
Doherty amplifier appears in Fig. 9.
The comparatively recent availability of tetrode transmitting tubes
with dissipation ratings in the tens
of kilowatts has made possible the
more efficient adaptation of the
Doherty amplifier in use today. In
this design, the control grids of
both tubes are fed an essentially
constant level of RF excitation.
Control of the output level of each
tube is accomplished by modulation
of the screen grid voltage as in Fig.
10.
5495.00 (150 MHZ)
MARTI
On negative peaks and up to
carrier condition the Doherty acts
as a conventional class B linear
amplifier. On positive peaks, where
the majority of the power is consumed, it functions as an impedance- modulated amplifier operating in class C. The amount of
power supplied by each tube over
the range from 100- percent negative
modulation to 100- percent positive
modulation is shown in Fig. 8.
In practice, two additional refinements to the theoretical quarter wave transformer are necessary to
make the system function. First,
because the transformer follows the
power amplifiers, it must have a
power capacity of twice the carrier
power of the transmitter. Unfortunately, a quarter-wavelength of
3- 1 /8 -in line at 300 m is not easily
realized. The transformer is therefore synthesized using a 90° n network.
Secondly, the 90° shift of either
of these methods will cause the
output of the carrier tube to lag
that of the peak tube by 90 °. To
compensate, the input to the grid of
the peak tube is delayed by 90° by
In this modified version, the
proper operation of the system is
not dependent upon the linearity of
the control grid, and both tubes
may be operated class C, yielding a
high PA efficiency and also a comparatively high overall efficiency.
The present 50 -kW version of this
system requires 120 -kW total power
input when modulated at 100 percent with a steady -state sine wave.
Overall recovered RF feedback is
also employed to linearize the
TX 76011
SI
system.
O
The Announcer's Friend
Indoor and Outdoor Sensors
Walnut- Finish Console
Gold Anodized Panel
Multi-Sensor Selector
Remote to Any Distance
1/2" Sperry 7- Segment Display
Slaves Available
Send for Spec. Sheet, Model 309.
Money Back Guarantee.
Also, a complete line of Weather
Instruments, Recorders and Controllers.
Texas
(214)
631 -2490
Electronics, Inc.
P. O. Box 7225B
Dallas, Texas 75209
For More Details Circle
For More Details
on Reply Card
Phone 601- 675 -2956
!\
,.
1C:1
CT?:
TOWER
PAINTING
PROFESSIONALS
will give you a
BETTER JOB at a
LOWER COST with no
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-
We paint all year round day
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Conjested areas -fragile
Antennas given special
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Let real experience simplify
your painting requirements
Dave Hovey General Contractor
Coffeeville, Miss. 38922
Tower Sales -Site Preparation
Rigging- Maintenance
Modifications -Consultation
645-9163
For More Details Circle
56
(45)
Z.
Circle (66) on Reply Card
(58) on Reply Card
BROADCAST ENGINEERING
Transient Response
neers who employ these filters in
(Continued from page 48)
their stereo equipment obviously
feel that these advantages outweigh the disadvantages that exist
in the transient response depart-
the response at 53 kHz or rely on
the natural distribution of energy to
prevent the upper sideband of
subcarrier from entering the S.C.A.
passband.
The lower sideband (38
15 kHz
= 23 kHz) is reaching down toward
the 19 kHz pilot and similar
considerations exist on this side of
the subcarrier. You can see where
the use of 15 kHz low pass filters
right at the audio input of the
stereo generator is. in many ways, a
very attractive proposition. Limiting
the input audio to 15 kHz right at
the very start means that the L +R
pass -band and the upper and lower
sidebands of the 38 kHz subcarrier
will be automatically limited and
the pilot will be protected, all in
-
fell swoop. The design
one
engi-
FREE CATALOG
®.IENBEN TOOLS
pü Skeet, 14w.wi., An..
ROt!
B -800
the five mixer series
practical console, stereo or monaural, designed with
flexible plug -in modules. perfect for production or small
stations.
a
ACCU -FIVE
versatile 5 mixer
-I= .:
ip
'4-7.
31/2"
rack mount console
I:-..,.--j.
n
o
0
N
(*tit
.
from the FULL CHOICE" line
AM /FM MONITORS
RECEIVERS
o
°
*
VIDEO
EQUALIZING
PULSE
Specifications
So good they have been
the "standard equipment" in
a major Network for 8 years.
Electrically and Mechanically
interchangeable
6 outputs
Loop through input
the eight mixer series
professional series of high performance consoles with
plug -in modular design, select your model, monaural,
stereo or simulcast
a
uw.,
Flexibility
Details Circle (95) on Reply Card
a
B -500
sa,0
®;11115°.'3
-R
harmonic distortion.
Getting back to our demodulator,
which was trying to add one
f'aithf'ul and one unfaithful square
wave, the result is of course,
tweezers, wire strippers, vacuum systems,
relay tools, optical equipment, tool kits
and cases.
Also Inc odes ten pages of
useful "Tool Tips" to aid in tool selection.
For More
1E1 v.ïáis5 i
filter actually reduces the total
HARD -TO -FIND PRECISION TOOLS
Lists more than 2500 items- pliers,
4117 N.
ment.
On the other hand, if we operate
wideband up to 53 kHz and then
cut off, the stereo demodulator will
find itself adding square waves to
sine waves because a pulse input
will be faithfully reproduced in the
L +R 15 kHz spectrum, but the
upper sideband of the 38 kHz
sub- carrier transmitting the L
component will be limited by the 53
kHz filter to an audio response
limit of 15 kHz, at least on the
upper sideband. Remember, however. that when we talk about
waveform distortion, we are looking
at square wave inputs. The harmonic distortion is not affected,
except that in the case of harmonies past 15 kHz, where the low pass
CDLIDA'!s
Reliability
Self- Powered
Distortion -free
performance
Thousands in use today
throughout the world.
Rugged
Extruded milled aluminum
housing with stainless cover.
Mount in rugged frames:
10 DA's per 3 RU frame and
3
DA's per
1
RU frame.
Price
Superior performance and
quality at competitive prices.
Availability
Stock to 30 days.
For immediate additional
information call:
Canada: 514-697-0811
U.S.A. (N.J.): 201-767-1300
Chicago: 312-991-4720
Los Angeles: 213- 789 -0574
AM/FM TRANSMITTERS
McMartin.
McMartin Industries. Inc 4500 South 76th Street. Omaha. Nebraska 68127 (402) 331 -2000
For
More Details Circle (26) on Reply Card
CENTRAL DYNAMICS LTD
December. 1975
www.americanradiohistory.com
Transient Response
(Continued from page 57)
something less than a reproduction
of the original square wave input.
To get good transient response up
to 53 kHz requires a bandpass
extending to about 150 kHz, if we
are talking about faithfully reproducing stereo audio inputs with
square wave content up to about 6
to 7 kHz. The actual bandwidth
requirement is rather flexible in
that it is directly related to how
much rounding of the waveform
one is willing to tolerate. At any
rate, if the response is allowed to
continue out that far, the designer
must feel very strongly that there
will be very little energy to interfere with the pilot or subcarriers by
Replace
Mercury
Vapor
Tubes
Directly
with
rry
virtue of natural spectral distribution.
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In every TV station, remote truck, or
audio /visual department the video engineer
has video timing problems. When he has a
Matthey "UN360" in his tool bag he can
deal with video timing up to and beyond
360° of phase at color sub -carrier.
It's fast to plug into cables. It's quick to
switch to the required delay and a screwdriver vernier gives ± 4ns of fine trim.
The performance is suitable for full color
timing and can be inserted directly into the
video path without any extras. The
equalizers are built inside the "UN360."
The "UN360" is in use by ABC, NBC
and CBS and many TV engineers across the
it's a
nation. Put one in YOUR tool bag
real aid.
Vs. Frequency
Figure 4 shows some oscilloscope
photos of filter effects on square
wave inputs at various audio fre-
Television Equipment Associates. k.
quencies. As you can see, the filters
do result in quite a bit of waveform
516 628.8068
BILL PEELER
Be. 1a91 BAYVILLE, N. V. 11709M
-
For More Details Circle
(50) on Reply Card
A COMPACT
WITH ALL
THE OPTIONS
Unique
approach to
cartridge
.
necessary.
Video Engineer's
Timing "Tool"
The
ROBINS /FAIRCHILD
Model 659A,
REVERBERTRON, is a complete dynamic reverberation system designed to
enhance Broadcast /Production or Recording Studio sound.
With solid state electronics and hign
performance electro- mechanical delay
lines in two separate enclosures, the
REVERBERTRON is compact in size yet
loaded with features. Continuous revert)
mix controls, VU metering, selectable
decay times, 3 band equalization and
remote control .. to name a few. All in
7" of rack space.
REVERBERTRON! Designed to fit your
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FOR COMPLETE DETAILS, CALL OR
tape
equipment.
.
'
V
ELEC- TRONICS, INC
701 Chestnut St.. Trainer, Pa. 19013
IEEEPHONE (215)
For More Details Circle
58
4975100
(67) on Reply Card
WRITE SAM JONES.
ROBINS O FAIRCHILD
Robins Industries Corporation
75 Austin Boulevard, Commack, N.Y. 11725
(516) 543 -5200
A
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(62)
on Reply Card
Beaucart is coming.
For More Details Circle
(51) on Reply Card
AGAIN & AGAIN
O
POTOMAC
INSTRUMENTS IS
vCT
First Approved Antenna Monitor
First Harmonic Reading Standard Broadcast
FCC
/4,
AM- 19(204)
Field Strength Meter
First Digital Antenna Monitor
First Frequency
Synthesized
and Coherent Detector
F
AM 19D(210)
RF Bridge Source
SD-31
First Solid
State VHF Combination Field
Strength Meter &
Generator
RF
And
IM-41
FIM -71
Other FIRSTS to be Announced
CONTACT US NOW FOR DESCRIPTIVE LITERATURE ON OUR
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932 PHILADELPHIA AVE.
SPRING, MD. 20910
(30) 589.3125
transient response of the transmitter is.
You could use the composite
output. but a de- emphasis network
will have to be inserted between the
monitor and scope to simulate the
de- emphasis in the receiver. Connecting at the composite output will
not give you any idea of what the
stereo transient response is like
because you're ahead of the demodulator. The easiest method is to use
a good quality stereo tuner, keeping
the modulation low to minimize the
I.F. bandwidth required. Simply
connect the scope to the left or
right channel outputs. being careful
to keep the cable capacitance low
or use a low cap probe.
Be sure that the tuner you choose
does not have any 19 kHz filters
built in! Some receivers included
these tillers to prevent beats with
the bias oscillators in tape recorders
when recording FM programs.
Modern tape gear has much higher
bias frequencies and most of the
newer tuners have the standard deemphasis only, so you shouldn't
have too much trouble finding a
suitable unit.
Details Circle (53) on Reply Card
distortion with pulse type inputs.
The big question is whether the
human ear can actually hear these
aberrations; one of the topics we'll
investigate in Part 2 of this series.
Another big question is whether the
transmitter audio input will ever see
any square waves of this type with
THE NEW STANDARD
COVERS
AM BAND PLUS HARMONICS
MHz
The Model FIM -41 Field Strength Meter
has many more features
-
program material for a signal
source, which we will also investi-
Measures Harmonics to -BO dB
gate in Part 2.
Figure 5 shows a 7.5 kHz square
wave as reproduced with a bandwidth function flat to 50 kHz and
about 10 dB down at 100 kHz.
Note that there is very little
rounding, but also note that we
have not begun to cut off until ten
octaves above the frequency of the
input signal. If you would like to
test the transient response of your
system, you will have to do more
than simply tack a scope onto the
audio line when you get to the
transmitter. FM modulation monitors usually have 15 kHz low pass
filters in the stereo section, so any
test made in the audio circuits past
these filters is not valid: at higher
frequencies you will simply get a
sine wave output with a square
wave input no matter how good the
TO 5
High Adjacent Channel Rejection
Ganged Oscillator /Receiver Tuning
Stable Operation over wide Temperature
Range
Low Battery Drain Circuits
Front Panel Speaker
Large illuminated Meter and Tuning Dial
Indicates field strength accurately down
to 10 p volts /M
RF input jack for tuned voltmeter applications
CONTACT
ON OUR
US NOW FOR COMPLETE DETAILS
LINE OF FIELD STRENGTH METERS
PTOMAC INSTRUMENTS
932 PHILADELPHIA AVE.
MARYLAND
20910 (301) 589 -3125
SILVER SPRING,
For More
Details Circle (54) on Reply Card
December, 1975
59
www.americanradiohistory.com
Checking transient response in
FM systems is a little complicated
but well worth the effort. For
00'
off
the air?
You'll know about it in as little
time as 3 seconds with the BELAR
AS -1 Audio Sentry. The lack of
audio for any preset interval between 3 seconds and 60 seconds
will activate the AS -1's alarm circuits-to provide both an aural
and visual alarm.
Vital to AM, FM and TV operations,
the AS -1 sells for only $250. and
delivery is immediate. A small investment for an important assignment, minimizing dead air time.
Order yours today.
BELAR
ELECTRONICS LABORATORY, INC.
Lancaster Avenue at Dorset.
Devon, Pa. 19333 Box 826,
(215) 687 -5550
instance, you may find that your
is superior to your telco
loops in this respect. A phase shift
at the high end of the telco loop
passband can result in overshoot.
too, so if you really process your
audio and want to transmit those
clipped waveforms, you may want
to look into a composite microwave
transmission system. Or perhaps
you're an audio perfectionist who
believes in transmitting everything
exactly as it was recorded, audible
or not. On the other hand, maybe
you're more concerned about optimum stereo decoding and would
rather see the response take a dive
at 16.5 kHz and not worry about
interference with the pilot or S.C.A.
In either case, there will be
something of interest for you in
Part 2 of our transient response
investigation; CAN ANYONE
FEEL MY PULSE?
O
transmitter
new
generation
of cartridge
tape
machines.
A
Beaucart is coming.
here Accuracy Counts...Count on Beier
For More
Details Circle (55) on Reply Card
QUALITY TALKS
FOR
KKAA
Aberdeen. South Dakota
Continental's new 5/10 kW AM
transmitter is setting records for
acceptance. It has performance
and efficiency, with the cleanest
sound around. Listen to Continental: quality talks.
C.a-x_tinL.e..nLLa..L
-4.-4'
Products
Pulse
Generator
Systron - Donner has introduced
the Model 110C Pulse Generator
featuring an output amplitude of 20
volts with a S nonosecond rise time.
The output amplifier has independent controls for rise time, fall
time. and voltage upper and lower
levels, which may be set independently between +20 and - 20 volts.
Output impedance is switchable to
50 or 1000 ohms and may be
operated in a normal or complement mode. The complement mode
allows negative pulses to be produced or simulation of pulses with
duty cycles approaching 100 percent.
Repetition rate is variable from
0.5 Hz to 50 MHz. Delay and width
are variable from 10 nsec. to 1 sec.
Additional controls include external
empty
tape reels and boxes
for your audio/video needs
36 types
CONTINENTAL
MFG.
CO.
DALLAS. TEXAS 75217
ELECTRONICS
BOX 17040
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For More
(Continued from page 55)
rsc corp.
$n
stock
GrT CATALOG
-
0
RBe 175
1291 Rand Rd. OesPlaines, IL 60016 312/2970955
For More Details Circle (96) on Reply Card
Details Circle (61) on Reply Card
NOW you can
PULSE CROSS
CONRAC*
RNC9 & RND9
monitors inexpensively in a
couple of hours with the
(L) XPAK
PULSE CROSS ADDER KIT
No need to buy a monitor or costly
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and a few spare moments. We furnish
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Ultra Audio Pi tee
"Picture Techniques" WORLD
LEADER IN PULSE CROSS DESIGNS
BOX 921
BEV. HILLS CA 90213
(213) 849 -1433
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BROADCAST ENGINEERING
60
www.americanradiohistory.com
trigger. external drive. manual trigger. synchronous gating. asynchronous gating, square wave, and
double pulse.
For More Details Circle
(87) on Reply
Card
A"SOUND" COMPETITIVE EDGE!
The STE -100 STEREO PHASE ENHANCER...
can minimize "Phase nulling" in "Mono -sum " signals,
and ensure your "Sound quality" in todays competitive markets!
!
!
Digital
Multimeter
A built in provision for temperature measurements which can be
made with an optional probe. is one
of the features of the new compact
digital multinleter announced by
Philips Test & Measuring Instruments, Inc., a subsidiary of North
American Philips Corporation. Designated the PM253I, this new
UMM offers a number of features.
The heart of the PM253I is an
LSI circuit which performs part of
the analog circuit functions. the
A D conversion and the digital
signal evaluation. The LSI chip
reduces the total number of circuit
components and is thus responsible
for the compact dimensions, the
low weight and the moderate cost
of the instrument. The integrated
circuit directly drives a bright. 31/2
digit. seven segment 0.315 inch
LED display with automatic decimal point. -l'he display is recessed
to be more readable even under
high ambient light conditions. The
instrument also features a polairty
indication, as well as indication for
range overloading and low battery
loading.
The normal multimeter functions
are selected by pushbuttons and the
range is set by means of a rotary
switch. The sanie input sockets are
used for voltage and resistance
measurements, so that for approximately 90% of the instruments use
the leads do not need to be
changed. AC and DC voltage are
measured in 5 ranges each from 0.1
to 600V and 0.1 to 1000V, respectively.
Resolution is 100uV in the 0.1 V
range and accuracy is .0.2% fsd
±_0.3% rdg for DC and f0.2% fsd
%D rdg torr AC. Errors due to the
instrument loading the circuit
under test are eliminated by the
highinput impedance of 10 MOhms.
Five AC and DC current ranges
A fsd,
extend from 100 uA to
with a resolution of 100 uA in int
f1
1
lowest range.
For More Details Circle
LARRON ELECTRONICS, 1216 Niter Rd,Sunnyyale,CA, 94086,Call(408)736 -8737
For More Details Circle
on Reply Card
AURAL STUDIO -TRANSMITTER &
REMOTE PICKUP LINKS
Systems For
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Others on Special Order
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SANTA BARBARA
RESEARCH PARK
111 CASTILIAN DRIVE, GOLETA, CALIFORNIA 93017
Telephone (805) 968 -9621 / Telex 658448 / Cable MOSELEY
For More Details Circle
`J
1
(48) on Reply Card
From
80 Years of Experience
Comes the Finest
Am & FM Broadcast Transmitters
Ever Manufactured!
CSI ELECTRONICS INC.
u
ELECTRONICS INC.
/
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2607 River Road
Cinnaminson, New Jersey, 08077
For
Telephone: (609) 786 -1060
ore Details Circle (57) on Reply Card
100?
yes & no.
THE f:14 EBS
Encoder
-
Decoder and optional receiver
in
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Two temperature- compensoted precision audio oscillators.
A CMOS digital comparator Decoder.
IC
Not three separate units.
No expensive crystals, ovens. or dividers
No piezoelectric or mechanical filters.
reliabilty, 2 -day burn -in, stereo line switching...
yes, it makes sense. no kidding.
(88) on Reply Card
Broadcast Engineering Techniques
December, 1975
(52)
For More Details
www.americanradiohistory.com
206 Doyle Ave
Novlden,e
Circle (59) on Reply Card
R.1.
02906
14011 861
-6007
61
advertisers'
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CONSULTING RADIO ENGINEERS
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345 Colorado Blvd.
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61
3
Member AFCCE
15, 46
RALPH E. EVANS ASSOCIATES
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Potomac Instruments, Inc
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Consulting TeleCommunications Engineers
AM- FM- TV- CATV -ITFS
3500 North Sherman Boulevard
MILWAUKEE, WISCONSIN 53216
PHONE: (414) 442 -4210 Member AFCCE
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RCA Communications
Equipment Systems Div.
33, 35, 37
Ramko Research
41
Recording Supply Corp.
Recortec. Inc
Robins /Fair .nild Industries
Corp
Shintron Company, Inc.
Shure Broth( rs, Inc
Sound Dynamics
Sparta Electronic Corp
Spotmaster
Superscope. Inc
Systems Marketing Systems
Taber Mfg. & Engineering Co
Telemation
Telemet Company
Television Equipment
Association
Telex Communications, Inc
60
54, 55
SMITH and POWSTENKO
Broadcasting and Telecommunications
Consultants
2000 N. Street, N.W.
Washington, D. C. 20036
(202) 293 -7742
58
14
Cover
4
54
5
8, 36
20
45
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7
58
16
53
56
Tenter ..
Texas Electronics, Inc.
Time & Frequency
UMC Electronics Co.
UREI
Ultra -Audio Products
Video Aids Corp.
of Colorado
Vital Industries. Inc.
Ward -Beck Systems Ltd
Wilkinson Electronics, Inc
Cover
3
52. 58, 60
10
60
Joseph & Donna Roizen
VIDEO CONSULTANTS
International TV Systems
Marketing /Technical Writing
800 Welch Rd., Suite 354
Palo Alto, Ca. 94304
Tel: (415)326 -6103
MIDWEST ENGINEERING ASSOCIATES
eonsutEin9 Engineeas
6934 A N. UNIVERSITY
PEORIA, ILLINOIS 61614
(309) 692 -4233
CE3
9
Cover 2
58
/ Atlanta. Georgia 30326
Applied Video Electronics, Inc.
STUDIO SYSTEMS DESIGN AND INSTALLATION ENGINEERING. REFURBISHING/
MODIFYING COLOR CAMERAS AND
For More
OUADRUPLEX VIDEO TAPE RECORDERS.
Post Office Box 25
Brunswick, Ohio 44212
Phone (216) 225 -4443
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BRoaDcaSTenuneeRinG
Oscar Leon Cuellar
Regional advertising
sales offices
Mountain View, California
Dennis Triola. 2680 Bayshore Frontage Rd.,
Room 102. Mountain View, Ca. 94043, (415) 9610378
Consulting Engineer
1563 South Hudson
(303) 756 -8456
DENVER, Colorado 80222
Kansas City, Missouri
John Cox. 1014 Wyandotte St., Kansas City. Mo.
64105. (9131 888 -4664
Indianapolis, Indiana
Roy Henry, 2469 E. 98th St.,
46280, (317) 846 -7026
Indianapolis, Ind.
New York, New York
Stan Osborn, 60 E. 42nd St., Room 1227, New
York, N.Y. 10017, (212) 687 -7240
London W.C.2, England
John Ashcroft & Co.,
Square. Tele: 930 -0525
Member AFCCE
12
Bear
St..
Leicester
Amsterdam C. Holland
John Ashcroft & Co.. W. J. M. Sanders, Mgr., for
Beneluxe & Germany, Herengracht 365, Tele:
020-240908
Tokyo, Japan
International Media Representatives, Ltd., Shiba Kotohiracho, Minato -ku, Tele: 502 -0656
P. H. LEE
ASSOCIATES, INC.
Over 36 Years in Communications
And Broadcast Engineering
AM -FM -TV Frequency Measurements
P.O. Box 1575
Thousand Oaks, Calif. 91360
(805) 492-5055
(213) 889-7769
BROADCAST ENGINEERING
62
www.americanradiohistory.com
PROFESSIONAL
HITE
TELECOMMUNICATIONS
AND
BROADCAST CONSULTANTS
Sala
,
Programing
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raid
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HAROLD D. RUSSELL
SERVICES
WANTED (CONT.)
FREQUENCY MEASURING SERVICE -WE'RE M2
MONITOR REPAIRS- MOBILE UNIT -covers
Northern 76 Ill., Eastern Iowa, Eastern Minn.,
Southern 45 Wis., Western Mich., and Western
Ind., monthly. Radio Aids, 528 Ravine Ave., Lake
2 -74 -tf
Bluff, Illinois 60044, (312) 234 -0953.
NON -COMMERCIAL WSMH -FM, LANCASTER,
NY. desperately needs donations of studio and
technical equipment of all types. Donations tax deductible. Please help us. Contact Mike Arnold,
GM, WSMH -FM, St. Mary's High School, Lan12-75-11
caster, NY. 14086. (716) 683 -4824.
N
transBROADCAST CRYSTALS for AM, FM or
mitters. Frequency change, repair or replacement
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Don't be without a spare crystal. Repair of G.R.
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Consulting Radio Engineer
Over 30 years experience with the
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COMMERCIAL RADIO MONITORING CO. Precision frequency measurements since 1932. Local
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SPOTMASTER PARTS -24 hour service. Repairs
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Franchised Spotmaster repair service. 90 day
MEDIAS /BROADwarranty. COMMUNICATION
CAST COMPONENT DISTRIBUTORS, P.O. Box
54, Allentown, Pa. 18105, 215- 437-0607.
Advertising rates in Classified Section are 15
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Each initial or abbreviation counts a full word.
Upper case words, 30 cents each.
Minimum classified charge, $2.00.
For ads on which replies are sent to us for
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processing of replies.
Classified columns are not open to advertising
of any products regularly produced by manufacturers unless used and no longer owned by
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TRAINING
EARN YOUR ELECTRONICS DEGREE by correspondence, G. I. Bill approved. For free
brochure, write Grantham School of Engineering,
Information Desk, 2000 Stoner Avenue, Los
Angeles, Calif. 90025.
8 -72 -tf
FIRST PHONE in six to twelve weeks through
tape recorded lessons at home plus one week
personal instruction in Boston, Philadelphia,
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Telephone 213- 379 -4461.
8 -75-tf
ONE STOP FOR ALL YOUR PROFESSIONAL
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BUILD YOUR OWN TV AND RADIO
FOR 38 YEARS, Industry leader, Don Martin
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8 -72 -tf
PRODUC-
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Air Mailed $1.00. Don Britton Enterprises, P.O.
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CAMERA TUBES...ALL TYPES EXCEPT ORTHI
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N CAMERA. TK-10, 11, 30 or 31.
Electronics should be reasonably intact, need not
be working. Kenneth Tusar, 201 Evergreen 5-1C,
Vestal, New York 13850. 607- 797-3941.
10-75-3t
RCA B &W
URGENT -READY TO BUY A.M. TRANSMITTER,
50,000 watts. Used br reconditioned, In good
condition. Write to: Cie. Internationale de
Radiodiffusion 19, rue Burq, 75018, PARIS,
12 -75-lt
France. Tel: 254-37-06.
December, 1975
FOR SALE
MICA AND VACUUM transmitting capacitors.
Large stock; immediate delivery. Price lists on
request. SURCOM ASSOCIATES, 1147 Venice
Blvd., Los Angeles, Cal. 90015 (213) 382 -6985.
6-75-tf
RCA TTSOAH complete less control console,
Channel 7, including side band filter, harmonic
filter, color notch filter. Spare parts and spare
tubes. Contact Hal Hackbarth, KHQA TV, Quincy,
12-75.1 t
Illinois, 217-222-6200.
CALL LETTERS FOR SALE: If you're looking for
a new image this might be the answer. We're
willing to sell our call letters, KOFE, so we can
have a new image too. Telephone (208) 245-4559.
12 -75-lt
SCREW KIT for XLR plugs, cable mount, male or
female. 3 kits for a dollar ppd. Tenet 4122
Kroemer Road, Fort Wayne, Indiana 46818.
12 -75-31
FOR SALE: 1 Sarkes Targian Slide Projector
MDSP -80 (color capable 100 slide random access),
$1,200.00; 1 Sarkes Targian Multiplexes MMP4 -M
(color capable), $1,000.00; 2 Bell & Howell Film
Projectors MEVMS (color capable; less than 350
hours usage), $1,500.00 each; 1 Ampex VR -1100
VTR with vertical lock servo, Amtec, drop out
comp, proc amp, no headwheel, no monitor
bridge, $3,000.00; 3 Mark 10 ball bearing
headwheel panels, $2,000.00 each; 1 Richmond
Hill Special Effects MVSP -6, 29 wipes, positioner,
25 feet of cable solid state color capable; like
new, $2,500.00. Contact Don Hain, 8425 Peach
12-75-lt
St., Erie, Pa. 16509, 814- 868-4654
EQUIPMENT FOR SALE
SPOTMASTER, FIDELIPAC, RUSSCO, ROH,
ELECTRO- VOICE, OTARI, RAMKO, SCOTCH,
STANTON, NORTRONICS, SHURE, SENNHEISER, TELEX, MAGNECORD, and VIKING are
all items distributed and serviced by COMMUNICATION MEDIASI BROADCAST EQUIPMENT DISTRIBUTORS, P.O. Box 54, Allentown, Pa. 18105.
215-437-0607. "Sudden Service" our specialty.
6- 75-12t
WHATEVER YOUR EQUIPMENT NEEDS -new or
used -check us first. We specialize In broadcast
equipment. Send $1.00 for our complete listings.
Broadcast Equipment & Supply Co., Box 3141,
3-75-tí
Bristol, Tenn. 37620.
MAGNECORD PTO-A RECORDERS. Rebuilt units
and new and used Magnecord, Telex, Viking, and
Spotmaster parts. Huge supply, lowest prices.
REBUILT CARTRIDGE TAPE EQUIPMENT. Soptlessly clean and thoroughly tested. 30 day
moneyback guarantee. ONE YEAR warranty.
REPAIR AND RECONDITIONING SERVICES for
cartridge equipment by factory trained technicians. Send for complete Information:
AUTODYNE, Box 1004, Rockville, Md. 20850,
(301) 762-7626.
8-75-t f
Single Edge, Tape Editing,
Flyer, RALTEC, 25885 Highland, Cleveland, Ohio 44143.
9-75-ßt
RAZOR BLADES.
$23 /M,
BROADCAST CRYSTALS for AM, FM or TV transmitters. frequency change, repair or replacement
of oven types. Also new vacuum types for RCA,
Gates, Collins, etc. transmitters. Quality products, reasonable prices and better delivery! Don't
be without a spare crystal. Frequency change and
service for AM and FM frequency monitors. Over
30 years in the business. Eidson Electronic Co.,
Box 96, Temple, Texas, 76501. Phone (817)
773 -3901.
12-74-If
AMPEX MM -1000 eight track 1 Inch tape
machine, with sync and tape lock accessories,
one alignment tape and 5 reels of 3M mastering
tape. Approximately 30 hours use. Write: Dept.
341, Broadcast Engineering, 1014 Wyandotte,
K.C., Mo. 64105.
10-75-31
63
www.americanradiohistory.com
EQUIPMENT FOR SALE (CONT.)
HELP WANTED
A FEW COMPETITIVELY PRICED used Revox A77
Completely reconditioned by
Revox, virtually indistinguishable from new and
have the standard Revox 90 day warranty for
rebuilt machines. Satisfaction guaranteed. Example, A77 with Dolby, $675, plus shipping.
Write requirements to ESSI, Box 854, Hicksville,
N.Y. 11802 (516) 921 -2620.
10-75-6t
decks available.
STODDART RADIO interference -field intensity
meters. Stoddart NM -22A, 150KHZ- 32MHZ. Complete - $2,195, less antennas - $1,595. Stoddart
NM -30A, 20- 400MHZ. Complete - $1,295. Stoddart NM -52A, 375- 1000MHZ. Complete - $1,495,
less antennas - $1,095. All are in excellent
condition and calibrated prior to shipment.
Surcom Associates, (213) 382 -6985.
6-75-tf
MOTORS FOR SPOTMASTERS
NEW Paps hysteresis synchronous motor HSZ
20.50- 4 -470D as used in series 400 and 500
machines. Price $49.00 each prepaid, while they
last. 90 day warranty. Terms check with order
only, no COD's. Not recommended for Tapecaster
series 600 or 700.
TAPECASTER TCM, INC., Box 662
Rockville, Maryland 20851
1
-72 -tf
FOR SALE: Television STL System Ratheon KTR
2 -7 GHZ dual link for audio and video complete
with ant., trans. line, and 8' X 12' reflector. Also
TR 22 High band color video tape machine. Write
WXON -TV, P.O. Box 2020, Southfield, MI, 48075
or call 313-355 -2901.
11 -75-tf
SPOTMASTER EQUIPMENT AND PARTS now in
Texas from Sales Southwest, 4002 Houston
Highway, Victoria, Texas 77901. 512-578-4323.
11 -75-tf
VIDEO JUKEBOX cassette programmer, like new,
VJB -12 with VJB -1. Channel 2 Cablevision, Box
1, Oxford, MS 38655. Phone 234 -8537 (AC 601).
12-75-lt
ELECTRONIC MAINTENANCE TECHNICIAN /ENGINEER, with executive potential, for Computer
Animation system and supporting hardware.
Should also have a good familiarity with basic
broadcast video equipment. New York City location. Call J. Mitwelt, (212) 628-5987, 10-12 a.m.
10-75 -3t
MOVE UP from your present job in broadcast
engineering. We handle all engineering jobs and
openings coast to coast. Send full resume confi-
dentially now. The AMPS Agency, 6331 Hollywood Blvd., Suite 623, Los Angeles, Calif. 90028.
Tel: (213) 462- 7301.
8 -73-íf
-A
TV MAINTENANCE TECHNICIAN
major
eastern market quality conscious TV operation is
looking for that unique, logic minded technician
to fill a vacancy in our maintenance department.
This well -paid, challenging position is a rare
opportunity to work in a self -fulfilling job, in a
people oriented atmosphere. An equal opportunity employer. Write Dept. 342, Broadcast
Engineering, 1014 Wyandotte St., Kansas City,
Mo. 64105.
11 -75-2t
NEW PATENTED master antenna system used
throughout U.S. needs local supervision of installations one day per week. made over $200.00
per day last year in supervision fees. Only top
I
broadcast troubleshooters need apply. Send
complete resume to Melvin Cohen, 1620 N.
Federal Highway, Boynton Beach, Fla. 33435.
11 -75-2t
TELEVISION ENGINEER: Excellent opportunity
for Studio-Transmitter Technician with Heavy
Maintenance Experience. Good Salary, Top
Benefits, established UHF Network Affiliate in
ideal community. Send reply to Chief Engineer,
KJTV -TV, P.O. Box 226, Bakersfield, Calif. 93301.
An Equal Opportunity Employer.
12.75-1 t
T.V. ENGINEER- Minimum 5 years experience
(Educational and /or Commercial) in design,
operations and maintenance of audio and video
electronic systems. Some supervisory responsi-
bility. Salary negotiable. Equal Opportunity
Employer -Submit (prior to December 15, 1975;
resume to: Dr. Joseph S. Gardiner, Instructional
Resources Center, State University College,
Oneonta, New York 13820.
12 -75-lt
TECHNICAL SPECIALIST -Background in electronics and experience in educational or commercial T.V. Capable of maintenance and operations of equipment in T.V. studio and closed
circuit system. Salary negotiable. Equal Opportunity Employer- Submit (prior to December 15,
1975) resume to: Dr. Joseph S. Gardiner, Instructional Resources Center, State University
12-75-lt
College, Oneonta, New York 13820.
RADIO AND POWER PLANT ENGINEERS, AN-
TENNA RIGGERS. Supervisory openings are
available overseas with Voice of America.
Transmitter Technicians- Openings in California,
North Carolina and Ohio. Salaries $12,285 to
$17,556. Civil Service Application (Form SF -171),
available at post offices and federal buildings,
should be sent to: VOA Personnel Office, HEWSouth Building, 330 C Street S.W., Washington,
DC 20547. AN EQUAL OPPORTUNITY EMPLOYER.
12-75-1t
MEDIUM MARKET AM DAYTIMER SEEKS CHIEF
ENGINEER RESPONSIBILITIES INCLUDE REMOTE TRANSMITTER TWO AIR STUDIOS
MOBILE REMOTE BROADCAST STUDIOWAVE.
STL EXPERIENCE PREFERRED, SEND RESUME
REFERENCES TO DEPT 344, BROADCAST ENGIWYANDOTTE
NEERING,
1014
STREET, KANSAS CITY, MO 64105.
11 -75-2t
AMPEX SERVICE COMPANY: Complete factory
service for Ampex equipment; professional
audio; one -inch helical scan video; video closed
circuit cameras; video systems; instrumentation
and consumer audio. Service available at 2609
Greenleaf Avenue, Elk Grove Village, III. 60007;
500 Rodier Dr., Glendale, Ca. 91201; 75
Commerce Way, Hackensack, N.J. 07601.
12 -75-3t
ENG DELIGHT,
314 -449 -0917.
IVC 960CD,
Edits, DOC, 12K,
12-75-1t
REMOTE PICKUP STATIONS -Used Marti MRreceiver, 150-170 MHZ, three frequency,
$235.00 prepaid. Cen -Com, 2425 E. Union Bower,
Irving, Texas (214) 438-6259.
12-75-1t
200
SPARTA /BAUER Model 710 AM transmitter, 10
KW serial 101, high performance modulator -like
new one year use. Frequency 1500 KHZ, new
tubes, $17,000.00. Contact Edward Alatorre, (213)
965 -2441 and (714) 996-5685.
12-75-2t
FOR SALE: BPI Automation AR -1000, digital
clock, two net joins, three Revox, Carousel with
BPI random select, remote control, three bay
deluxe cabinet, stereo line amp, spare set
AR -1000 cards, all wiring. No problems, taken
from service for format change. System three
years old -excellent condition. Plenty of expansion room. WIZO AM -FM, 615 -794 -4103.
12-75-1t
COLLINS 21 E/M 5 KW A.M. Transmitter -Good
Working Condition. Was main on air transmitter
-meets Proof. $4000.00. KJJJ Radio, 631 North
1st Avenue, Phoenix, Arizona 85003. Attention:
Mr. Lou Burke.
12-75-1t
AEL DFM Exciter and stereo generator. In
excellent condition. Removed working for replacement by new generation equipment. Available immediately. Contact Dick Johnson, 1044
Westwood, Faribault, Minnesota 55021. (507)
334 -6735.
12-75-2t
VIDEO TAPE: Scotch 3M type 400, cleaned and
evaluated, good condition, half hour reels with
plastic shipper, 35 Dollars each. Short ends type
400 7 -28 minutes in length, One Dollar per
Minute. Scotch 399, $5.00 per 30 minutes. Ampex
175 video tape $15.00 per half hour. MONEY
BACK GUARANTEE. QUAD TAPE SALES, P.O.
Box 23534, Washington. D.C. 20024. Phone 703569 -9212.
12 -75-31
BROADCAST
MAINTENANCE
ENGINEER
Excellent opportunity for individual who will be
responsible for the main,enance, installation and
operation of components in a broadcast quality
television system. 5 -10 years maintenance experience required. Specific familiarity needed
with Quad recorders, RCA 44 cameras, production, audio and digital equipment. Individual
should be able to work well independently.
Generous remuneration, extensive benefits and
career development. Please send your resume in
confidence, including salary history to:
W. F. Schreiber
Employee Relations Services
T
-1
AMOCO
STANDARD
OIL COMPANY
(INDIANA)
200 E. Randolph Drive
Mc 0302
Chicago. III. 60601
An Equal Opportunity Employer
mil
BROADCAST ENGINEERING
64
www.americanradiohistory.com
GÜARAPIflEb
15 S
o
FCC Type Accepted and Certified
TWO TONE GENERATOR
TONE DECOOEP
AM RECEivr,
a
Tr
'/
7
IL I161Yl.lWT
EBS
IIY{
When that real emergency happens, the 25
second EBS alert signal can be the most
important air time in your operating history.
FCC has now strengthened the EBS Alert
Signaling Requirements starting April 16,
1976. To help you meet this requirement.
TFT has built its new Model 760 EBS
system as failsafe and versatile as humanly
SYSTEM
... and
priced it within easy reach
of every broadcaster. Write or call for full
facts and features'
possible
Outside of California call toll free
800 -538 -6884
'System price starts at $140.00
EBS 760 - READY WHEN IT COUNTS
TIME AND FREQUENCY
TECHNOLOGY,
INC.
3000 OLCOTT STREET, SANTA CLARA, CA 95051 (408) 246 -6365 TWX No. 910- 338 -0584
For More Details Circle
(2) on Reply Card
www.americanradiohistory.com
Hand-held hotline.
-to
Finally there's a microphone that follows the news wherever it goes
the
end of a mile -long parade or to the center of a championship golf course.
The new Shure SM82 super- rugged microphone -with its own built -in, line level amplifier
the long- distance hotline designed for broadcasting. Used
with a telephone line or voice coupler, the SM82 becomes a complete remote amplifier /microphone with line -level output and a self- contained peak
limiter to prevent overloading. All in the new Shure SM82, the long hotline
for the short deadline.
-is
Shure Brothers Inc.
222 Hartrey Ave., Evanston, IL 60204
In Canada: A. C. Simmonds & Sons Limited
r4
SHURE
Manufacturers of high fidelity components, microphones, sound systems and related circuitry.
For More
Details Circle (3) on Reply Card
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