Moseley TRC-15A User manual

INSTRUCTION MANUAL
MODEL TRC-15A
REMOTE CONTROL SYETEM
KOSELEY ASSOCZATES, INC,
Santa Barbara Research Park
111 Castilian Drive
Goleta, California 93017
Revised
July 1975
[phone]

I.
II.
III.
IV.
v.
VI.
VII.
VIII.
TRC- 15A INSTRUCTION MANUAL
TABLE OF CONTENTS
INTRODUCTION
Page
1
SPECIFICATIONS 1
UNPACKING
INSTALLATION
A. General Information
B. Wireless FM
C. Wireless AM
D. Equipment Location
E. Studio-Transmitter Interconnections
F. Metering
G. Control
3
3
4
a
a
10
15
19
OPERATION 22
CIRCUIT DESCRIPTION 23
A. Control Generator 23
B. Control Demodulator 27
C. Audible Metering Generator 29
D. Subaudible Metering Generator 31
E. Audible Metering Demodulator 33
F. Subaudible Metering Demodulator 35
G. Subcarrier Generator 37
H. Subcarrier Demodulator 39
ADJUSTMENT 39
A. Routine
B. Internal
C. Control Generator
D. Control Demodulator
E. Audible Metering Generator
F. Subaudible Metering Generator
G. Audible Metering Demodulator
H. Subaudible Metering Demodulator
I. Subcarrier Generator
J. Subcarrier Demodulator
MAINTENANCE AND REPAIR
39
40
40
40
41
42
42
42
42
43 ---
44
TRC-15A -j,-

INSTRUCTION MANUAL
MODEL TRC- 15A
REMOTE CONTROL SYSTEM
I. INTRODUCTION
The Model TRC-15A Remote Control System was designed specifically
to remotely control FM and standard broadcast transmitters. A total
of 15 metering channels and 15 bi-directional (on/off, raise/lower,
etc. ) control functions are provided by the system. Interconnection
between studio and transmitter requires only a single full-time, two-
way, voice-grade wire line or radio link. The environment in which
the equipment normally functions and the operator using it have both
been carefully considered. Excellent performance has been achieved
by careful design, and available options make the’ TRC-15A a versatile
remote control system.
The standard TRC-ISA uses a telephone line interconnection between
the studio and transmitter sites. This system is defined by referring s
to it as the TRC-15AW. When options are installed to enable sub-
carrier or other wireless techniques to be used, it is referred to as
the TRC- 15AR.
II. SPECIFICATIONS
Number of metering channels
Metering system input
Calibration controls
Calibration voltage source
Metering system stability
Control System
Number of channels
Control output ratings
15 (selected one at a time)
Approximately 1 VDC for full-scale
studio-meter deflection; nominal
ZOK resistive floating input, insu-
lated for 350 VDC
Multiturn potentiometers
Internal Zener diode
With weekly transmitter-unit checks
and daily studio-unit checks, better
than 1% exclusive of operator setting
or reading error
15 On/Raise and 15 Off/Lower,
isolated
1 ampere maximum, 120 VAC
maximum
TRC-15A -l-

Telephone line studio-transmitter
interconnection (TRC- 1SAW)
Telephone line impedance
Telephone line levels
Control tone frequency
Metering tone frequency
Allowable line loss
Radio link studio-transmitter
interconnection (TRC-15AR)
Radio link impedances
Radio link levels
Control subcarrier
frequencies
Metering tone frequency
Metering tone level
Metering subcarrier (option)
Semiconductor devices
Operating temperature range
Power requirements (each end)
19 inch vertical rack space
Domestic shipping weight
600 a
0 dBm, adjustable
300 Hz to 375 Hz
800 Hz to 1200 Hz
30 dB (with 0 dBm send levels)
2000 G nominal
1. 5 volts peak-to-peak
26 kHz typical for monaural STL.
110 kHz typical for composite
stereo STL,
20 Hz to 30 Hz
Adjustable up to 6 volts peak-to-peak
behind 600 ~2
67 kHz typical, 41 kHz alternate
All silicon diodes, integrated cir-
cuits, and JEDEC-registered
transistors
-30°C to t6O”C
120/240 VAC, 50-60 Hz, 20 watts
5$ inches, each end
60 pounds
TRC-15A
(Rev. l/75) -2-

III. UNPACKING
The TRC-15A units should be carefully unpacked and inspected for any
shipping damage. Keep all packing material in case a claim is to be
made against the carrier for damages. Should this inspection reveal
any damage, immediately file a claim with the carrier.
It is recommended that the front panels be pulled forward for a brief
superficial inspection. Be sure the various printed circuit boards are
secure, the integrated circuits and transistors are seated in their
sockets, and that the fuse-holders are installed. The rear door of the
transmitter unit should be swung down and the relays and fuses con-
firmed as being in place.
IV. INSTALLATION
A. General Information
IT IS HIGHLY RECOMMENDED THAT NO CONNECTIONS
BE MADE TO THE TRC-15A UNTIL THE BASIC CONCEPTS
OF HOW THE SYSTEM OPERATES ARE UNDERSTOOD BY
THE INSTALLING PERSONNEL. These concepts, as well as
installation suggestions and comments, are explained in the
next few pages of this manual.
Bear in mind that if the two units are interconnected with a telephone
line, the system is a TRC-15AJ& or if wireless (subcarrier) inter-
connections are used, the system is a TRC-15AR,
Connections which will be required at the studio unit are to the power
source and either the telephone line (for the TRC-15AW) or the STL/
radio equipment (for the TRC-15AR). At the transmitter site these
same connections will be required in addition to connections to the
control and metering circuits. The control and metering connections
should not be made until the studio and transmitter units of the
TRC-15Ahave been interconnected and confirmed as working alone.
The studio unit of the TRC-15A sends control signals in the region of
300 Hz to the transmitter site. In the wire-line TRC-15AW system
these signals are sent to the transmitter via a telephone line. In the
radio TRC-15AR system the signals are sent via a subcarrier on a
radio link. The transmitter unit returns metering signals to the studio
unit. These signals are in the region of 800 Hz to 1200 Hz in the
case of the wire-line TRC-15AW, or they are in the region of 20 Hz
to 30 Hz in the case of the radio TRC-15AR system.
I
TRC-15 -3-

The wire-line system is illustrated in block diagram form in Figure 1,
and the elementary radio system is illustrated in Figure 2.
B. Wireless FM
If the telephone line interconnection is not used, the control signals
are sent to the transmitter site by using subcarrier techniques. As
shown in Figure 2, the control generator at the studio frequency-
modulates a subcarrier generator. The output of this subcarrier
generator is then applied to the multiplex or subcarrier input of an
STL (microwave) transmitter. In this manner, the control signals
“ride piggyback” on the STL going to the transmitter site. This sub-
carrier generator is a standard addition to the studio unit of the
TRC-15A.R for wireless operation.
At the transmitter site the subcarrier output from the STL receiver
is applied to a subcarrier demodulator located in the TRC-15AR trans-
mitter unit. The output from this demodulator is a replica of the
control signal which originated at the studio. This signal is then
internally applied to the control demodulator in the TRC-15AR as in
the basic system. The subcarrier demodulator at the transmitter
site is a standard addition to the transmitter unit of the TRC-15AR for
wireless operation.
In a similar manner, the metering signals may be returned from the
transmitter to the studio by using a subcarrier. As shown in Figure 3,
the metering generator frequency-modulates a subcarrier generator
at the transmitter site. This subcarrier generator is usually a part
of the main FM transmitter. As with the control signals, the meter-
ing signal now rides piggyback on the broadcast carrier in the form
of an SCA signal which is then received at the studio. Here the sub-
carrier is extracted and demodulated by an SCA receiver. The out-
put of this receiver or SCA demodulator is a replica of the metering
signal generated at the transmitter site.
When the metering signal is returned to the studio in this manner, it
is customary to use the frequency range of 20 Hz to 30 Hz for the
metering signal. In this way, program material such as background
music may also be broadcast on the SCA subcarrier. It has been
found in practice that there is little interaction between the two. This
low-frequency metering signal, which is referred to as the subaudible
metering signal, is usually adjusted to modulate the SCA subcarrier
about 14 dB below program. Because it is in the low audio spectrum
and because it modulates the subcarrier at a low level, it causes
little degradation of the music service. By the same token, low-pass
TRC-15A -4-

STUDIO SITE TRANSMITTER SITE
METERING
DEMODULATOR +--
I I
I
t
i
METERING METERING
T GENERAToA --+-
SAMPLE
INPUTS
FiG. I-BASIC TRC-ISA REMOTE CONTROL SYSTEM
EQUIPMENT ILLUSTRATED COMPRISES THE STANDARD
WIRELINE SYSTEM (TRC- 15AW)

z
n
L STUDIO SITE TRANSMITTER SITE
Multiplex portion
-+ of microwave link
going to transmitter DEMODULATOR DEMODULATOR
site. --I
4”’
Control Tone _\ Subcarrier\ LMultiplex LControl Tone
modulated by output from
control tone STL receiver
Metering Tone Metering Tone
20-80 Hz
Fig. 2 - Basic Wireless FM version of the TRC-15A.
Equipment illustrated corn rises the standard
wireless system (TRC-15AR . At "A" is an SCA
P
subcarrier generator, usually a part of the FM
transmitter. At "8" is an FM/SCA receiver
external to the TRC-15AR.

STUDIO SITE TRANSMITTER SITE
ti,”
Control Tone _\ Subcarrier -I 4 Multiplex LControl Tone
modulated bv outbut from
control tone STL'receiver
Metering Tone-l SubcarrierA
modulated by
metering tone
L-Subcarrier L-Metering Tone
modulated by
metering tone
Fig. 3 - Wireless FM version of the TRC-15AR
Equipment shown is the same as in Fig. 2
with added optional subcarrier equipment
for metering return. A subcarrier generator
& been added for telemetry-only service at
and an internal subcarrier has been added
for'demodulation of this subcarrier at "5".

filtering in the TRC-15AR keeps the normal program material above
40 Hz out of the metering circuitry.
If the FM transmitter does not contain an SCA generator, then a
subcarrier generator is installed at the transmitter site as shown at
“A” in Figure 2. If program service is to be accommodated, the
Moseley Associates Model SCG-8 SCA Generator is recommended.
No modifications are necessary to it or to the TRC-15A.R for such
operation. If program service is not a requirement, then an internal
subcarrier generator can be added to the TRC-15A transmitter unit
as shown in Figure 3. This telemetry-only SCA generator is installed
in place of the subcarrier generator jumper/terminating board in the
TRC-15AR transmitter unit. Such an added subcarrier generator at
the transmitter site is an available option which may be added to the
standard wireless TRC-15AR.
If the receiver or monitor at the studio does not have an internal SCA
demodulator but a sample of the broadcast subcarrier is available,
then a subcarrier demodulator can be added to the studio unit of the
TRC-15A as shown at “B” in Figure 3. This subcarrier demodulator
will accept the subcarrier and demodulate it to recover the metering
signal. This signal is a replica of the original metering signal
generated at the transmitter site. It is internally routed to the
metering demodulator in the TRC- 15A.R studio unit. This added sub-
carrier demodulator at the studio site is an available option which
may be added to the standard wireless TRC-15AR.
C. Wireless AM
Figure 4 illustrates a modification of the wireless FM installation
applicable for wireless & broadcast transmitters. Here the control
tones are conveyed to the transmitter site as in Figure 2, but the
metering tone is returned to the studio directly on the main AM broad-
cast signal. As in the case of FM with its SCA subcarrier, the
metering signal is in the 20 Hz to 30 Hz range. The modulation of
the AM carrier by the subaudible metering signal is set to about 5%.
(6% is the maximum allowed by the FCC Rules.)
D. Equipment Location
Providing that installation personnel understand the principles involved
for the particular version of the TRC-15A being used, installation of
the studio and transmitter units may proceed. The first stage of
installation will involve the remote control units only; no connections
will be made to the transmitting equipment. After the remote control
units are installed and their operation is’ confirmed, the remainder of
the installation will be accomplished.
TRC-15A -8-
(RW. 7175)

STUDIO SITE TRANSMITTER SITE
CONTROLTONE
-I SUBCARRIER--.-I
MODULATED67
CONTROLTONE
+
METERING
DEMODULATOR @
METERINGTONE
~~~~~~~~~~~~~t~~~~~
T
Multiplex output CONTROL
from STL receiver TONE
AM broadcast METERING
signal returning
to studio 1 GENERATOR
METERINGTONE
Fig. 4 - Wireless AM version of the TRC-]5AR
Note the similarity to the Fig.32. At "A" is a
standard broadcast (AM) transmitter, and at "B" is
an AM receiver tuned to that frequency. TRC-15AR
equipment involved is the standard wireless system (TRC-15AR).

Since the studio unit will receive frequent operator attention during
the routine controlling and logging operation, its location at the studio
should receive careful attention. Since occasional readjustment of the
front-panel controls at the transmitter site may be required, this
unit, too, should be mounted at an appropriate height. In each case
it is recommended that the racks should be well bonded to a good
system ground.
E. Studio-transmitter Interconnections
The various interconnections should now be made. The control path
to the transmitter site and the metering path returning to the studio
should be completed. This may be nothing more than just connecting
the telephone line, or it may involve the full complement of subcarrier
equipment. Figure 5 illustrates the telephone line connections, and
no comment is needed.
Figure 6 illustrates subcarrier and radio equipment connections and
should be understood to avoid error. Occasional reference to
Figures 2 and 3 may be helpful. At the studio the control output con-
nection will normally deliver a subcarrier frequency-modulated by the
control tone. This subcarrier will be routed to the STL transmitter
multiplex or subcarrier input. If the TRC-15AR internal subcarrier
generator is not used, it is replaced by a jumper/terminating board,
and the control output connector will deliver the control tone itself.
This tone may be routed either to an external subcarrier generator
at the studio, or it may be applied directly to the modulator of some
other system whose output is ultimately at the transmitter site.
Metering input to the studio unit will normally be applied from the
output of a telemetry receiver. The output of this receiver will nor-
mally be the metering tone itself. The metering receiver may be any
receiver capable of extracting the metering tone from the broadcast
transmission. For FM an SCA receiver modified for telemetry pur-
poses is customarily used. For AM any receiver with a 1.5 volt
peak-to-peak subaudible output may be used. (The studio unit of the
TRC-15A can be easily modified to increase its sensitivity by as much
as 20 dB above this figure.)
If this metering input is a sample of the undemodulated subcarrier as
radiated by the FM transmitter, then an internal subcarrier demodu-
lator substitutes for the jumper/terminating board in the studio. The
metering input connector should then have applied to it the SCA sub-
carrier sample which is then internally demodulated in the TRC-15AR
studio unit.
TRC-15A -IO-

REAR OF STUDIO UNIT
.300@0~
( 120 OR 240 VAC )
INE
1
-
TELEPHONE LINE
POWER INPUT
( 120 OR 240 VAC )
REAR OF TRANSMITTER UNIT
I I
TELEPHONE LINE
FIG. 5 - TELEPHONE LINE INTERCONNECTIONS

POWER
( 120 OR
REAR OF STUDIO UNIT
INPUT
240 “AC ) L MTRO
IN
J I
CONT.
OUT
n I0000000[
L RECEIVER
\ METERING INPUT FROM TELEMETRY
OR MONITOR
REAR OF TRANSMITTER UNIT
__ METERING OUTPUT TO
- TRANSMITTER OR SCA GEN
POWER INPUT 0 0 0 0 0 0 0
( 120 OR 240 “AC )
43 CONTROL INPUT FROM
STL RECEIVER
FIG. 6 - WIRELESS INTERCONNECTIONS

The transmitter unit metering output connector will normally deliver
the metering tone. The output from this connector will be applied via
a mixing network, such as a Moseley Associates MIU-2 Metering
Insertion Unit, either to an external subcarrier generator (commonly
done in SCA applications) or to another return link to the studio, such
as an AM transmitter. When the TRC-15A.R transmitter unit contains
the subcarrier generator, the output from the metering connector will
be a subcarrier which is applied to the FM transmitter multiplex or
subcarrier input connector.
The transmitter unit control input connector will generally be connected
to the multiplex or subcarrier output from the STL receiver. Under
these conditions, the internal subcarrier demodulator in the TRC-15AR
transmitter unit will demodulate and extract from the subcarrier a
replica of the control tone originating at the studio. If the control
signal is already in the form of the audible control tone generated at
the studio, then the internal subcarrier demodulator is replaced by a
jumper/terminating board. The control input connector then has
applied to it the control tone which is routed internally to the control
demodulator.
When both studio and transmitter units have been mounted in their
respective racks or cabinets and the electrical interconnections have
been made, the next step is to check that control signals originating at
the studio are received correctly at the transmitter. Likewise, the
metering signals must ‘be satisfactorily returned from the transmitter
to the studio site. It is advisable at this point to have made no con-
nections to the transmitter control output terminals or to the metering
input terminals.
Power may now be applied to both units. If the telephone line is of a
satisfactory quality (in the case of the TRC-15AW) or the radio equip-
ment is properly connected (for the TRC-15AR), then pressing the
RAISE button at the studio should make the Raise relay at the transmitter
site pull in. Pressing the LOWER button should make the Lower relay
pull in. Pressing a numbered button at the studio should cause the
corresponding numbered relay at the transmitter to become energized.
Should there be a problem at this point, check the interconnections
between studio and transmitter and be sure that each line is carrying
the correct signal. To assist in the initial setup, recommended
standards are shown in Table 1. The first three measurements in-
volving the telephone line are made at the telephone line terminals.
The remainder are applicable to wireless systems and are made at
the Type BNC (coax) connectors. Refrain from making internal
TRC-15A
(Rev. 3/76) -13-

adjustments unless a reading is definitely unsatisfactory in a manner
that is correctable by adjustment.
TABLE I
Recommended Control and Metering Signal Standards - TRC-15A
Control tone leaving studio
Metering tone leaving transmitter
Maximum telephone line loss, 300 Hz
to 1200 Hz (with 0 dBm send level at
each end of line)
0 dBm
0 dBm
30 dB
Subcarrier generator output at studio
site (used for control; connects to
S’TL transmitter)
1. 5 volts peak-to-peak
Subcarrier demodulator input at trans-
mitter site (used for control; driven by
STL receiver)
1.5 volts peak-to-peak
of subcarrier
Subcarrier generator output at trans-
mitter site (used for metering return
to studio; connects to FM transmitter)
Subcarrier demodulator input at studio
site (used for metering; driven by FM
receiver)
Adjustable up to 6 volts
peak-to-peak
1. 5 volts peak-to-peak
of subcarrier-
Control signal direct output at studio 1. 5 volts peak-to-peak
(connects to external subcarrier
generator)
Control signal direct input at trans-
mitter site (driven from STL via
external subcarrier demodulator)
1. 5 volts peak-to-peak
Metering signal direct output at trans-
mitter site (connects to AM transmitter
or to external subcarrier generator)
Subaudible: up to 6 volts
peak-to-peak, adjustable.
Audible: approximately 1. 5
volts peak-to-peak, fixed
Metering signal direct input at studio
site (driven from AM or SCA receiver)
Modulation of AM transmitter by
metering signal
1. 5 volts peak-to-peak of
metering signal
5% (6% maximum)
Deviation of SCA subcarrier at FM trans-
mitter site by metering signal 800 Hz
TRC-15A -14-

F. Metering
MAKE NO CONNECTIONS TO THE METERING INPUTS
ON THE TRC-15A UNTIL THE REQUIREMENTS OUTLINED
IN THE FOLLOWING PARAGRAPHS ARE UNDERSTOOD.
The metering signals applied to the TRC-15A metering inputs are not
-
the same voltages or currents that are indicated on the transmitter-
panel meters. Instead, they are derived independently in a manner
such that they do not interfere with the regular meters but are repre-
sentative of the readings of those meters. Because the actual voltage
or current to be measured is not brought out from the transmitter,
but rather only a sample of it is, this voltage is also known as the
metering sample. Figure 7 will help to illustrate this point.
In “A” of this drawing, resistors Rl, R2, and R3 have been added to
develop an output voltage representative of plate voltage. Resistors
RI and R2 are typically in the several megohm range, with wattage
ratings in the vicinity of 10 watts to 20 watts. Stable metal-oxide
resistors are preferred. Resistor R3 is in the vicinity of 10Ka to
lOOKa and serves to keep the output sample terminals at a reasonable
voltage should the external load (the remote control metering input) be
removed. The target output voltage is 2 volts DC, with a 1 volt mini-
mum and a 10 volt maximum. Less than 1 volt may not allow full-
scale deflection of the studio meter, and more than 4 volts may result
in difficult setting of the calibration controls. This assembly is avail-
able from Moseley Associates as Type PVK-1 or PVK-2.
In Figure 7 “B,” a shunt resistor in the vicinity of 1sZ is shown added
as R4. This resistor develops a sample of plate current but at a safe
location. The value of this resistor should be calculated to develop
2 volts target with normal plate current flowing,
MAKE CONNECTIONS TO THIS RESISTOR SECURELY:
IF IT OPENS OR IF ITS CONNECTIONS BECOME CORRODED.
THE OUTPUT SAMPLE TERMINALS WILL HAVE EXCESSIVE
VOLTAGE ON THEM. PARALLELED RESISTORS ARE PRE-
FERRED FOR THIS REASON.
Bear in mind that the TRC-15A metering inputs must be in the form
of DC. Hence, if it is desired to include a sample of filament voltage
in the metering line-up, the AC voltage must be rectified. A simple
method of accomplishing this is shown in Figure 8 at “A.” This same
technique may be used for monitoring line voltage. The filament volt-
age may be rectified directly if it has a center tap or one side is at
ground potential. This device is available as an accessory from
Moseley Associates, Type LVK-1.
TRC-15A -15-

--
+
--
---+-
RFC
>
. mn
RI
RZ ’
i-
83
DERIVING PLATE VOLTAGE SAMPLE
--II-
I
I
0
‘LATE I
:URRENT
SAMPLE
)UTPUT
I
FIG. 7
DERIVING P.LATE CURRENT SAMPLE

-
I
I
u 0 TRANSMISSION
SCREW
:.
FIG. 8
.-
- .-

Antenna base current may be measured by noting that the tower is a
linear device, and then measuring voltage instead. The two are
directly related. Figure 8 “B” has been proven to be satisfactory.
The 10 pf capacitor may be a short piece of coaxial cable or a small-
value transmitting-mica capacitor. The two capacitors in series form
an RF voltage divider, down to approximately 20 volts to 50 volts
peak. This RF is rectified by the diode (preferably germanium, but
use a 150 volt or 200 volt high-speed device in any event) and smoothed
by the 0.01 uf capacitor. For high base voltage installations, reduce
the value of the 10 pf capacitor so that the RF voltage at the junction
of the two capacitors is of the order of 30 volts peak. This same
system may be used to measure transmission-line or co-on-point
current. This unit is available from Moseley Associates as Type
RFK-1.
In FM installations a scaled-down version of the system shown on “B”
may be used. Shown in “C,” this system must be carefully constructed
In this case, purchase from a manufacturer is recommended. This
device is available from Moseley Associates as Type RFK-2 or RFK-3.
The outputs from reflectometers and frequency monitors are generally
low (of the order of 25 microamperes at low voltage in the case of a
typical reflectometer), and in the case of frequency monitors an offset
adjustment may be required (no input results in half-scale deflection).
Both of these complications are solved by using a DC amplifier, such
as the Moseley Associates Type DCA-1. The DC amplifier is connected
between the reflectometer or monitor and the input to the TRC-15A.
Bear in mind that whatever the source of the met,ering voltage sample,
it should measure in the vicinity of 2 volts DC when a 22K resistor
is connected across it, and it should measure not more than 10 volts
when this resistor is disconnected. If the sample is above or below
ground, all terminals and points where it is exposed should be covered.
It must not be more than 350 volts peak or DC referenced to ground,
or damage may result to.the TRC-15A. It should not be more than
50 volts above or below ground unless wiring is protected. The use
of shielded wire, conduit, and other techniques to keep RF out of the
metering samples should be encouraged.
If the installing personnel understand the metering sample requirements,
they may proceed with installing the metering circuitry. As an alter-
native, the metering circuitry installation may be delayed and accom-
plished along with the control circuitry installation.
TRC-15A -18- Rev 13 Dee 1977