Purpose - General purpose HF transmitter/receiver.
Units - All the units of the AN/URC 32 except the inboard RF amplifier plus the AN/SRA 502 external amplifier.
Frequency Range - 2 to 24 MHz transmit; 2 to 30 MHz receive
Power : 1 kw intermittent; 700 watts steady state.
Modes - Same as AN/URC 32.
Antenna: Normally used with 35 foot whip antenna
Power Requirements: 540 watts 115/230 VAC 50/60 Hz. Single phase for URC-32
6,000 watts 380/450 VAC 50/60 Hz. Three phase for SRA-502
Combined weight: 1,105 pounds 
Applicable manual: BRCN 4314

Brief Description - During transmission, the Radio Set Group OA-5079/URC-32 generates an RF carrier and provides facilities to modulate or key this carrier with an input signal. The modulated or keyed RF carrier is amplified by the Amplifier-Power Supply Group AN/SRA-502A and then fed via the Antenna Coupler AN/SRA-22, to the antenna.

During reception, the RF signal received at the antenna is fed via the Antenna Coupler AN/SRA-22 to the Radio Set Group OA-5079/URC-32, where it is amplified and demodulated. The demodulated signal is fed to a local handset or to remote signal lines.

OA-5079 AN/URC 32 - HF TRANSMITTER- RECEIVER
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Purpose - General purpose, HF, manually operated transceiver.
Frequency Range - 2 to 32 MHz
Frequency Stability - 1 part in 10-8 per day.
Modes - CW, MCW, AM (Receive only), Compatible AM (TX only), ISB, USB, LSB, FSK
Output - 125 Watts in compatible AM. All other modes - 500 Watts adjustable
Power Required - 115 V AC 60 Hz

Major Units -

Interconnection Box - contains main power & connecting cables.
Relay Assembly - Modifies the operating mode during tuning of couplers.
RF Amplifier - Increases the power from .15 watt to 500 watts (125 for AM).
Converter Oscillator - Translates IF to RF during TX and RF to IF during receive.

Amplifier Converter Modulator - Translates AF to IF during TX and IF to AF during receive.
Converter Monitor - Permits the equipment to be operated on CW or FSK modes.
Amplifier Control - Dual channel audio amplifier.
Signal Comparator - Permits comparison of a reference oscillator to an external frequency standard.
Control Power Supply - Enables local or remote operation.
Power Supply - provides DC voltages.
Electronic Equipment Air Cooler - Supplies air needed for cooling. 

AN/SRA-502 RF Amplifier
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Full Description : AMPLIFIER-POWER SUPPLY GROUP AN/SRA-502A
Stock No. 5820-21-041-5212. Consisting of the following internal units:

1 Amplifier, Radio Frequency AM-5155/SRA-502A 
1 Amplifier, Radio Frequency AM-5156/SRA-502A 
1 Power Supply PP-5139/SRA-502A 
1 Power Supply PP-5140 /SRA-502A 
1 Transformer, Power, Step down TF-5005/SRA-502A
1 Panel Indicator SB-5066/SRA-502A
1 Cabinet, Electrical Equipment CY-5120/SRA-502A

Specifications:

* Bandwidth: 1. 5 to 24.0 megacycles
* Gain Greater than 40 db
* Types of Excitation: Al (Single tone), A2, (MCW), A3 (RT) F 1 (FSK), A3a (SSB), or other
     transmission, within the bandwidth

* Power Input Levels (Signal)

(a) Single tone: 28 milliwatt input for 700 watts mean power output
(b) Two tones: 10 millwatt input per tone for 1000 watts peak power output

* Power Outputs:

(a.) 1000 watts peak power when used with a single exciter for Al or A3a transmission
(b) 700 watts mean power when used with a single exciter to transmit a continuous signal
(c) 500 watts total mean power for multi-channel operation

* Input Impedance: 75 ohms (50 ohms with RF input adapter)
* Output Impedance: 50 ohms

*Primary Power Requirements: 6000 watts, 380/450 volts, 50/60 cps, 3 phase
* Heat Dissipation: 5000 watts
* Physical: measures 73-3/4 inches high by 20-5/8 inches wide by 27 inches deep, and weighs 693
   lb.
* Manual reference: BRCN 4314

All units, except the Indicator Panel, are housed in a shock-mounted steel cabinet, which is horizontally divided into two compartments, each with its own door and lock. The upper compartment contains' the RF amplifiers and controls, and the lower compartment contains the power supplies and the power transformer. The RF amplifiers and the power supplies are mounted on heavy-duty runners. Operating controls, fuses, indicating lights and a panel meter are accessible through cut-outs in the doors. Air inlet and exhaust ducts, and cable entries s are provided on the cabinet top. The indicator panel is mounted on the cabinet top and is angled towards the operator.
Brief Description:

The AN /SRA-502A is a two stage RF amplifier with its own built-in power supplies. Both stages of the RF amplifier section are balanced distributed amplifiers, which utilize transmission lines to feed the grid circuits and as the plate loads. The first (penultimate) stage is RF Amplifier AM5156/SRA-502A, which has 9 pairs of JAN 6688 tubes working in push-pull operation. It amplifies the RF input signal to the required level to drive the final stage.

The final stage is RF Amplifier AM-5155/SRA-502A, which has 8 pairs of 4CX250B air-cooled tubes working in a linear form of class AB1 push-pull operation. The output of the final stage is applied through a directional coupler to the antenna system. The directional coupler contains three probes, which feed samples of forward and reflected power to the indicator panel, which continuously monitors power output and VSWR.

Power Supply PP-S140/SRA-502A and Transformer TF-5005/SRA-S02A supply the plate voltage to the final stage. The remaining operating and control voltages are provided by Power Supply PP-5139/SRA-S02A. Heating elements are fitted in the cabinet base to provide means of drying out the equipment when operating under conditions of high humidity. A common metering instrument, in conjunction with five metering circuits, may be switched to read all of the internal DC supply voltages and to monitor the various check points in the equipment. Air flow and door safety interlock circuits are incorporated.

CONTROL CIRCUITS

Controls on the AN/SRA-502A are reduced to those necessary for applying supply voltages and for routine metering. No tuning is necessary after the initial "setting-up". Panel indicator SP-5053A/SRA-S02A may be used to control the equipment from a remote location.

REMARKS

The AN/SRA-502A is the Canadian equivalent of the British built AN/SRA-502.
The AN/SRA-502A is usually used as a component part of Radio Set AN/SRC-502A.

Antenna Coupler Group AN/SRA-22 is used to couple the AN/SRA-502A either to a long wire antenna or to a 35-foot whip antenna and provide 50 ohm matching. This panel connects to the CU-714/SRA-22  Antenna Coupler which is in a water-tight enclosure and is mounted at the base of the antenna.

Frequency Range: 2 to 30 MHz
Power  Input: 1,000 watts max.
Primary Power: 115/230 VAC, 50/60 Hz. 100 watts.

BRIEF TECHNICAL DESCRIPTION

The AN/SRA-22 is primarily a tuned circuit, in which the coil inductance, the coil tap and the capacitance are variable.The coil is formed by a silver ribbon wound on two drums, one metal and the other ceramic. The inductance of the coil is varied by winding the silver ribbon from one drum to the other. Maximum inductance is obtained when all the silver ribbon is wound on the ceramic drum. The drums are motor driven.

The coil may be tapped at any point on the silver ribbon by varying the position of a motor driven contact.The motors for the coil and tap drives are controlled by sending-potentionmeters and null-position indicators on the Coupler Control and by receiving-potentionmeters on the Antenna Coupler. The capacitor is a variable vacuum type and is positioned by a motor drive which is controlled by a 12 position switch. The capacitor may be switched in parallel or in series with the antenna. A wattmeter on the Coupler Control may be switched to indicate forward or reflected power.

Manual : NAVSHIPS 93286 

When the SB-5053A/SRA-502A is used as a component part of Radio Set AN/SRC502A, it is mounted on a hinged frame assembly and enclosed in a Cover Assembly. The complete assembly is mounted on the upper portion of Electrical Equipment Rack MT-2092/U, which is part of Radio Set Group OA-5079/URC-32. Except for the type of meters used, the SB-5053A/SRA-502A is identical to SB-5053/SRA-502.

On RCN installations the normal AC power switch is replaced with a key operated Rotary Action Lock Switch  to provide "MAN ALOFT" functionality. (Image courtesy Canadian Navy)

Freq. Range - 1.6 to 30 MHz (thumbwheels and channel) 
Power Output - 125, 400 or 1000 Watts 
Modes - LSB, USB, Compatible AM, CW, AFSK, FAX 
Units - Two RF 230SL HF Transceivers, 
One RF 2305-06 Control and distribution panel 
One RF 110A,  400 or 1 KW Amplifier. 
Two RF 236 Power Supplies for RF 230SL
One RF 652-08 Receiver Multicoupler providing 8 outputs from a single RF ant., 
One RF 258-06 Radio Remote Control unit providing remote capabilities for two RF 230SL, one VHF, one UHF and one HF Receiver.

Nomenclature - OA 8012/SRC consists of all units except frequency standard.

OT 13A/SRC 23 same as OA 8012 but does not have the receiver section.
Frequency Range - 2 to 29.9999 MHz
Tuning - 280,000 Channels. Automatic tuning from local or remote.
Modes of operation- AM, FSK (requires external keyer), CW, Voice or Data in USB, LSB, ISB.
Power Output - 1000 watts PEP in SSB, 500 watts CW and FSK, 125 watts in AM, 1000 watts in DATA. 
Power Requirements - 115 V AC and 400 Hz 3 Phase delta 
Associated Antenna - AN/SRA 34 coupler with Transmitting Fan or AN/URA 38 with 35 Ft whip 
Number Fitted - DDH 280 class have 7  (2 with receivers for data); AOR Class has 3 fitted (all without receivers) 
Type of Operation - Simplex or Duplex 
Frequency Standard - Requires 100 KHz external standard.
Cooling - Water Cooled 
Alarms - Monitored for fault and man aloft functions at the BZ 5006 (Summary alarm and Man Aloft Panel)

CU 938/URA 38 - Coupler
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Located at the base of 35' whips for matching output of the transmitter in the frequency range of 2-30 MHz

C 6705/SRC 23 - Receiver Control Indicator 
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Located in CCR to control AN SRC-23 Receiver section from remote.

C 6704/SRC 23 - Transmitter Control Indicator.
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Located in CCR to remotely control AN SRC 23 Transmitter.

ID 1370/SRC 23 - AF/RF Monitor 
Located in CCR to enable monitoring of the audio lines to the AN/SRC 23 transmitter and the RF lines from the transmitter.

MX5129/SRA 504 - HF Adapter 
Adapts output input lines of the AH/SRC23 to the ROS.

MX4845/SRA 34 - Adapter Control 
Adapts the AN URA 38 to the Diplex information from AN/SRC23.

C3698/URA 38 - Control Antenna Coupler 
Remotely controls the CU 938 coupler

AN/URA- 64 - RF Switching Group (Not shown). 
Consists of C 5240 Control indicator and SA 5053 (switch RF transmission). AN/URA 64 enables switching of AN/SRC 23 HF outputs to either a whip or a fan through the respective couplers.