Moseley PBR-21A User manual

INSTRUCTION MANUAL
for
MODEL P5R-21A
SOLID-STATE
REMOTE CO~TROL SYSTE~
MOSELEY ASSOCIATES, I~C;
P. O. Box 3192
SANTA BARBARA, CALI?ORNIA
revised
DECEMBER 1966

INSTRUCTION ~A~UAL
MODEL PBR-21A
SOLID-STATS
REMOTE CONTROL SYSTEM
Introduction and General Description
The Model PBR-2l Solid-state Remote Control System is desl~ned
to control AM. FM, and TV broadcast transmitters. 21 mete~lng
and 42 control functions are provided by this system which
requires only a single, two-way s1~nal circuit for operation.
This may be a wire line, with or without amplification, carrier
telephone aparatus, VP.F radio links, or aural and TV STL
multiplex ~ubcarrler circuits. Because of this design, there is
no necessity for a JC path between the transmitter and the remote
control point.
(
All of the transistors and diodes emoloyed in the Model PBR-21
System are silicon devices. The transistors are all of one type
and are mounted in sockets. Two svare transistors are provided in
both the Studio and Transmitter Control units. A panel containing
three illurnitated 411 rectangular meters is provided as a standard
item with each system. Each of the 21 metering positions can be
made to appear on any given meter by changing the jumper wires for
the meter lamps and metering signal in the Studio Control Unit.
It would be possible, also, to employ 21 separate meters, each one
displaying the information corresDondin~ to the selected push-
button. . .
The principles of operation employed in the PBR-21 Remote Control
System are straightforward. Three oscillators employing stabilized
torodial inductors and silver mica capacitors generate the LOW£R,
RAISE, and FAIL-SAPS control frequencies. The frequencies are
respectively. 1200 Hz, l~~O Hz, and 1720 Hz. The ?AIL-SAFE tone
is interrupted by a transistor gate to cause the stepper 3~itch in
the Transmitter Control Unit to advance and/or to seek its home or
calibrate position. A binary counter chain controlled by push-
button logic determines the proper sequency of interruption to the
FA:L-SAFE tone.
Telemetry is performed by converting DC sampling volta~es from the
transmitter. tower lights, etc. to a frequency operating in the
400 Hz to 750 Hz spectrum. NOTE: For certain applications when
the PBR-21 System 1s used 1n radio remote control system. the range
of telemetering frequencies is changed to a 22 Hz - 3D Hz instead
of ~OO Hz -750 Hz. Operation and functions remain the same. A
s1mple Schmitt trigger circuit and a diode pulse counter converts
this frequency back to DC for meter readout at the remote control
---------- - p-o~ - nt.
PBR/66

-2-
The Model PBR-21 Remote Cont~ol System conBists of three separate
units. The Studio Control Unit and the three-meter panel are
located at the remot~ co~trol point. The Tran3~1~ter Control Unit
is placed adjacent to the transmitter or transmitters being
controlled. 22 push-buttons arc located on the Studio Control Unit.
The first push-button is reserved for calibratln~ the meterin~
system; the remainin
b
twenty-one are :or control and meterin~. ~he
calibration button is red and is located at the upper left-hand
side of the push-button bank. A rocking arm swItch) with a center
off position, is used to transmit LOWER, RAISE (ON or OF~) commands.
SLOPE and CALI3. S~R controls on the Studio Control ~nlt permit the
calibration of the metering information. A power switch and power
line fuse post are also located on the ~ront panel of the Studio
Control Unit. Two indicator lamps show the status of the control
system. A small push-button enables the operator to quickly confirm
the information being received on any push-button selection.
The Transmitter Control Unit contains 21 multiturn calibration
controls, one for each of the metering channels. In addition to
the power switch, pilot lamp, ano fuse holder, three buttons enable
an operator at the transmitter site to operate the control system.
Fail-safe circuitry is included in this unit and will o~erate if the
control circuit 1s open for any period exceedin~ approximately 25
seconds. The output control circuitry of the ~odel PSR-21 can be
likened to one row of 21 SPDT center off switches, with all poles
tied together. The selection of these s~ltc~es is controlled by
the push-buttons on the Studio Control 0nit. and the position of
the selected switch 1s determined by the operatio~ of the LOWER-
RAISE switch, also on the Studio Control Unit. All control,
metering, and line connections are made on a barrier -strip located
on the rear of the chassis.
There are a total of 6 plug-in printed circuit boards containing
all of the essential electronic circuitry. Four of these boards,
Boards A, BJ C, and D) are located 1n the two ca~d ca~es mounted
on each side of the Studio Control Unit chassis. Boards ~ and F
are mounted in a single cage on the Transmitter Control Unit. The
boards a~e designed so they cannot be inserted into the socket
unless properly oriented. CAUTION: It is possible, however, to
interChange boards so always be sure that the p~oper circuit board
is plugged into the proper socket. The copper circuitry on each
printed board has been electroplated with a thin fl1m of gold to
prevent oxidation.
The power supplies, electric-wave filter, stepper switch, and
relays are mou~ted on the chassis of the Model P3R-21 Control System.
The relays are of the plug-in type and are held in position with a
retaining clamp.
When operating the Model PBR-21 Control System ove~ a radio or STL
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separately on the Studio and Transmitter Control Units.
PBR/66

Specifications
Control Functions
Metering
Metering Input Impedance
Control Relay Ratin~
Fail-Safe
Line Requirements
Calibration Reference
Mechanical
Power Requirements
Finish
Installation
-3-
21 RAISE, 21 LOWER Command~
21 telemeterin~ channels
o - 3 vOlts"DC (approx.) fOT
full scale deflection
25,000 ohms
2A/30VDC, 120 VAC, ~on-injucttve
load
Activated when control line
interruption exceeds 25
seconds
20 db allowable loss from ~OO Hz -
1800 Hz
Zener D.:!.ode
Studio Centrol Unit 7" X 1:1"
1vleter Panel 5 l/~II X 19"
Transmitter Control Un1t 5 l/~II X
19"
120/2~O VAC, 50 - 60 Hz
Anodized and etched aluminum panels
Prior to bench-testln€ the equipment or proceeding with the
installation, it is reco~~ended that the entire Model :'GR-21 be
examined for any damage or loose cO~~0nents due to shipping vibra-
tions. In particular, the inside of each printed circuit card cage
should be carefully examined. While the transistor sockets used
will firmly hold the transistors in place, a visual inspection is
suggested and any loose transistor should be well-seated 1n the
socket. NOTE: The transistor sockets are all oriented the same
way, and each transistor mounts in the socket in the same ~elative
position.
Before installing the Model PB~-21 Remote Control System, the equip-
ment should be ope~ated on a back-to-back basis so that personnel
can familiarize themselves with the ooeration of the unit. The cable
from the meter panel should ~e cannected 1n the correspondln~ socket
on the rear of the Studio Control Unit. The power cables from the
_____ ...... S ..... t .......... ll die And. T.J:.an s mi t t Q r Con" J!..0.l.- ",--In 1t::; ::; R-G-U~~G-t-W t...G---a----:;.ouc£r .... c;..c:;€l:-- ----
of 120 VAC, 50-60 Hz.
PBR/66

CAUTION: If the available power is 2~O VJ 50-60 Hz, change power
transformer primary wiring as shown on schematic dia~rams for the
Studio and Transmitter Control Units. A ~air of wires, or shielded
cable. 1s then used to connect the LINS inrut terminals of the
Studio Control Unit to the LINE input terminals on the Transmitter
Control Unit. The power switches on both units should then be
turned on. Occasionally the stepper switch mqy be actuated when
the power switch is initially tUrned on. This is a normal condition
and does not indicate any malfunction of the system. Next, depress
the red calibration button. This will cause the stepper switch to
advance to the calibrate or home position. The lamps in the left-
hand meter will turn on after the stepper has stopped and the meter
should have an indication near mid-scale. When the LOWER control
is actuated, the meter will fall to zero. Also, the lower relay,
K804, in the Transmitter Control Unit can be checked for operation.
If the meter does not read zero, adjust the CALlB. SET control for
zero with the LOWER control command on. Next, release the control
button, and adjust the S~OPE control unit until the pointer falls
between the t~o arrows mid-range on the meter scale. The system
i8 now calibrated. When depressing any othe~ push-button, the
stepper switch will automatically advance to that position. As
this is done. the red CYCLE lamp turns on and remains on until the
stepper switch has reached its proper position. At this time, the
red CYCLE lamp turns off and the green READ lamp tUrns on. If the
RECYCLE button is pressed, the circuitry will automatically place
the stepper switch i~ the home or calibrate position, and then
advance it until it comes to rest on the position corresponding to
the depressed push-button.
:f the RAISE or LOWER buttons on the Transmitter Control Unit are
pressed, the appropriate relays will fUnction. The position of the
stepper switch in the Transmitter Control Unit can be changed by
pressing the STEPPER button. When this button is pushed for
approximately 1 second, the stepper switch will move to the horne
position. Incre~ental steps can be made by pressing the STEPP~R
button for a brief moment. To advance the stepper switch to the
5th position, for example, the operator would press the STEPPER
button five times, each time being rather brief. No tally indication
is given the operator at the Transmitter Control Unit. A plastic
card is mounted on the panel, however. to easily identify each
meter position with the parameter it controls or telemeters.
A voltage sDurce. such as available from a volt-ohm meter. can be
placed between any given telemetering input and ground barrier
point. Next, push the button corresponding to this number on the
Studio Control Unit. By adjusting the calibration potentiometer
aSSOciated with this channel, the deflection of the selected meter
on the meter panel can be made to vary. Such back-to-back testing
will enable the operator to familiarize himself with the operation
-e-l "1'8-R="Z-:t Fferrrot e----euntTo-i- S-y-st-em and t-o -u-ooe-r-s-t-a-n-4------fl-ew-t-fle- ----
system works before it has been put into service.
PBR/66

-5-
The meter panel and Studio Control U~it should be installed 1n a
standard 19" rack at the desired remote control paint. The sl~nal
control pair sho~ld be ccr.nected to t~e approp~1ate bar~ier
terminals on the rear of the chassis. If the unit is to be used
over a radio link, such as the ~oseley Ivlodel f'C!.r-( ) Aural 3T~, then
the metering input and control output connectors will be separated.
These should be connected to the channels assigned to convey the
respective information. The meter panel is desl~ned to he mounted
directly above the Studio Control Unit. Panel notchings will match
standard 19" equipment racks used in broadcast service. A total
of 12 1/4" of panel apace is required for t~e studio control
equipment.
The 5 1/411 Transmitter Control Unit should be mounted near the
transmitter{s) it is to control so metcrln~ the control leads can he
, -
neatly installed. Power for the LOWER and RAISE output circuitry
of the Model PBR-2l 1s connected to the barrier term!nals ~arked
COMMON and 111VAC. Note that this circu~ t has a se-parate fuse on
the rear panel: and t~at this circuit 1s not connected 1n nny way to
the l17VAC obtained through the power cable. The contacts of the
control relays are rated at 60 watts into a resistive load. While
two sets of contacts are paralleled, care should he taken not to
attempt switching loads exceeding 60 watts. When heavy loads are
to be controlled, it is suggested that an ~ppropr1ate 117VAC power
relay be used with properly-rated contacts.
Line Regu:rementR
The Model PRR-21 is nornally manufactured ~or operation over a
single wire or telephone carrier circuit. The e~uirment is desl~ned
to operate with input levels ~anglnb from -20 dbm to +10 dbm.
Should amplifiers be used in the circuit, care should be taken to
limit the received sir,nal on both the Transmitter and Studio Control
Units to this range. If the line noise level or cross talk is
unusually hi~h, the LO~CR-~AISS control relays may be actuated.
This false relay operation will render the control system unreliable.
The output voltage frorr. the telemeterin~ oscillation in the Transmit-
ter Control Unit 1s normally wired to develop approximately 0 dhm
across a 600 oh~ line. :f it ~s desirable ~o ~ncrease or decrease
this level by 5 db, the o~tput connections on printed circuit Doard
F should be changed. (Refer to schemat:c Dra~ing 918-6127.)
Operation
Once installed, it is recommended that the equi~~cnt be left on
continuously. If the back-to-back bench-test procedure outlined
in the previous section waz done, operation o~ the equipment will
be quite ~traightforward. It will be briefly reviewed again. At
---- - t. he-r.emo _ te _. c_. QDtrolpoint J press the GALIn. pUSh-button on the
Studio Control Unit. Next J ac -E uaXe- the - t0WER - contr-ols
lIl1_
t_cJL9-_
nQ_
____ _
adjust the CALI;). SET contro: until the le"t-hand meter reads ze:ro.
Then release the LOWER control switch and adjust the SLOPE control
PBR/66

-6-
until the pointer falls between the two arrows. The system is now
calibrated. Next, push Button l. This will cause the stepper at
the transmitter site to advance to the first posItion. (When makin~
a change of only one position, the red lamp may not always operate.)
This position is quite often chosen as the PA voltage position.
When making the initial installation, the operator at the transmitter
should note the value of this parameter for the transmitter and
advise the operator at the ~emote control point. He should then
adjust the # 1 CALIBRATE control until the studio operator advises
him that the left-hand meter reading corresponds to the actual
transmitter PA voltage value. The other channels can be similarly
calibrated.
The broadcast transmitter can be placed in a radiate position, for
example, ~y pushing the #1 button and actuating the RAISE command.
Likewise. the carrier can be re~oved by operat~ng the LOWER com~and
when in the #1 pos~tion.
Theory of Operation
The control and metering functions of the I~odel PBR-21 Remote Control
System are accompliBhed using frequencies in the 400 to 1800 Hz
spectrum. Three stable oscillators operating at 1200, l4~O, and
1720 Hz operate LOWER, RAISE, and CONTROL circuits. As a 1720 Hz
control tone is present at all times except when the operator
wishes to select another control channel, the control tone also
acts as a fail-safe tone. ThUS, the 1720 Hz tone may be referred
to as either the control or fail-safe signal. The LOWER or RAISE
tones are applied to the system only when the operator desires to
control any given parameter at the transmitter site.
In addition to the fail-safe or control tone, a metering tone is
also present in the system. When wire lines are used, the metering
tone varies between 400 and 750 Hz. As indicated earlier, this
frequency may be in the 22 to 36 Hz band in the event a radio link
is beln~ used to relay control and metering signals associated with
standard or FM broadcast transwltters. In operation. DC samplin~
voltages from the transmitter are converted to tones by a linear
voltage-controlled oscillator in the Transmitter Control Unit.
These tones are converted back into analo~ information by a pulse
counter in the Studio Control Unit fo~ presentation on the
appropriate meter.
The circuits used in the Model PBR-21 when taken individually are
basic and simple to understand. However, the combined operation
may seem complex unless the operation 16 thoroughly understood.
The circu~try associated with the selection of an individual control
channel might, for example, seem rather complex. Before explaining
the detailed operation of the circuit, it would be well to briefly
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PBR-21 Control System.
PBR/66

-7-
Figure #1 shows a typical "AND" gate with five inputs. In order
for there to be any output signal, all five inputs must be present.
The waveforms drawn to the left of the five input terminals
represent the signals being applied to the "AND" p;ate. The output
waveform shown below the input signals is present only when Inputs
III and #2 and #3 and #4 and #5 are all on. Hence the name "AND".
Figure #2 shows another common circuit, the "OR" gate. This 1s
a three-input "OR" gate and the output pulse is present when
Input #1 or #2 or #3 1s present. The name for this circuit is
also obvious.
The Studio and Transmitter Control Units of the Model P8R-21
Remote Control System are shown 1~ block diagrams on Dr8win~s
SKA-6082 arid SKA-6083, respectively. Let us first consider the
operation of the Studio Control Unit. Drawing SKA-6082 is
divided into two sections: the bottom part, c~lled the Control
Section, cont~ins the 1200, l~QO and 1720 Hz osci:lators,
control tone gate, and summing amplifier. This section also
contains the telemetering detector circuitry for convert1nr, the
metering tones into a DC voltage for meter readout. The 800 Hz
low-pass fllter prevents the control tones from saturating the
input telemetering amplifier. A Schmitt trig~er follows the
telemeterlng amplifier and isolates the output DC signal from
changes 1n level of the input metering tone. When the 22 to
36 Hz telemeterlng frequency range is used, the 800 Hz filter,
Part 2-1076, is removed.
The blocks above the dotted line are ~ll part of the logic
circuitry which controls the control tone gate. That is, the
output of this section turns off (~ates) the 1720 Hz oscillator
at definite intervals each time the push-button selection bank
is operated. :t should be repeated tha~ short interruptions
of the 1720 Hz control tone will cause the stepper to advance one
position. A slightly longer interruption will move the stepper
switch to the home or CALIB. position. Thus, the control ~ate
receives two different Dulse widths to turn off the 1720 Hz tone,
in turn, are used to either advance the stepper switch incrementally
or to ~apidly advance it to the home position.
The timing information for the binary logic system 1s derived from
a continuously-running 9 Hz clock-oscillator. There are two outputs
from the clock. One of these outputs is applied to a trigger
switch.
PBR-2l/66

7A
+ loV
+16
R
0
+16 1
0 ,
i
+16 I
J ~ I
0
,---3
-li6
I
;
0
+16
-U
0 OUTPUT
'_____ 5
' .j
!
+16 I
...;
0
OUTPUT WAVEFORM
FIGURE 1.
FIVE INPUT HAND!! GATE
+16
-Ul
INPUTS
0
'-----y---J
1
~
~I
i I I
i
-tl6
:
0 n
__ 2
~l
4
~
+16
~
0 n 3
...
~1
...
OUTPUT
+ 16
1
"' 11JLJ-
0 L
_. I
OUTPUT
FIGURE 2.
THREE INPUT IORTI GATE
. ------------------------- - -
~-----------------------------------------------
:. "p Ie.. c..

-8-
If this switch is open, negatlve-goln~ pulses from the clock are
applied to the lnp~t of a five-stage bina~y divider. A c1rc~it
of this type has 2 or 32 different states of condition. ~hat is,
each flip-flop will either be in the flip or flop state. For
example. the 11th position would occur when the first, second, and
fourth stages are conducting in the same transistor while the
third and the fifth binary stages are conducting in the opposite
transistor. Thus, it is possible to derive a voltage from each
collector in all the binary flip-flops, and when properly selected
and applied to an "ANDI1 gate, this voltage will produce an output
signal which will tUrn off the trigger switch and prevent additional
pulses from advancing the binary divider. As soon as a different
push-button is selected, the trigger switch allows clock pulses
to advance: the binary chain. It will only stop when all five
inputs to the II AND'I gate, as se lec ted by the push-but ton assemb ly ~
again turn off the trigger switch to stop the- clock pulses.
The five binary stages have a capacity to assume 32 different
states. However, the stepper switch in the Transmitter Control
Unit has only 22 positions, 21 of them for control and rneterin~
and the 22nd for the calibration function. Thus. when the binary
divider reaches the state corresponding to #23, it must be reset
to zero to begin counting again so as to maintain synchronism with
the stepper switch. This is accomplished with another five-input
II AND'I gate. This is essentially the same as having a permanent
23rd push-button which, when activated, applies a pulse to the two-
shot reset generator. This generator has two outputs, one sli~htly
longer in duration than the other. The longer of the two outputs
is applied to t he binary divider to return each state to the zero
pOSition, This means that the binary chain is reset. ~hls same
pulse is also applied to the trigger switch to prevent clock pulses
from entering the binary divider chain.
A two-input ilORIl gate is connected to the collectors of tne first
binary stage so that an output pulse is obtained eRch time a
clock pulse enters the binary system.
The output from this "OR" gate is applied to a bi-stable gate
control fl:!.p-flop. A pulse from the IIOR
I'
J;ate will shift the
bi-stable flip-flop to the other state. which. in turn, controls
the control tone gate~ causing the 1720 Hz control tone to be
turned off. However, a pulse derived from the second output of
the 9 Hz clock restores the bi-stable gate to its p~evious position,
1/2 clock cycle later, thus restoring ihe output oi the 1720 Hz
tone to the line. It will be remembered that the two-shot reset
generator has two outputs. The long time-duration pulse resets the
binary divider chain to zero. The shorter output pulse 1s
applied to the bi-stable gate control flip-flop, which causes the
----- esn-t-p0-1-t.Q.fl..e-g..a-t-e -t -0 I!-emain c) Qspd ] on~ enough fo'!" the stepper swl tch
in the Transmitter Control Unit to move to the home position. The
PBR/66