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RS-100
Paramilitary spy radio set

RS-100 was a self-contained all-in-one paramilitary spy radio set, developed around 1964 by Sylvania in Mountain View (California, USA) 1 for the US Central Intelligence Agency (CIA) and the Defense Advanced Research Projects Agency 2 (ARPA, later: DARPA) [11]. It covers 2-24 MHz in the HF radio band, and produces an output power of 20 Watts. Intended as a successor to the modular RS-1 radio set, it was a ruggedized waterproof set for use in para-military operations. Part of the transceiver – the 20W transmitter – was developed by AVCO in Cincinnati (Ohio, USA).

The transceiver is housed in a green die-cast enclosure that measures 340 x 250 x 150 mm and weights 7.9 kg. 3 Controls and connections are protected by a watertight plastic cover that is held in place by two spring-loaded locking clips.

The CW transmitter can be operated by a crystal installed at the front panel, or by one of the 40 crystals that are installed in the AU-100 crystal selector, or by means of the OS-100 synthesizer. The receiver can be freely tuned over the entire 2-24 MHz range, divided over four bands, and is suitable for reception of CW, AM and SSB signals.
  
RS-100 radio

The device can be powered by an internal removable 12V battery pack, or by the external PS-100 power supply unit (PSU), or by an optional hand generator. When correctly adjusted, an output power of approx. 20W can be obtained. Messages can be sent in morse code, either with the built-in morse key or by means of the built-in KE/A-8 burst keyer. The latter is part of the CK-100 coder/keyer set and is complemented by a CO-8 encoder and a CA/A-3 tape cartridge [4].

The RS-100 was a co-development of CIA and ARPA, mainly because both agencies had similar requirements. During the project however, the requirements of the CIA changed, whilst those of ARPA remained unaltered. As a result, the set was never produced in large quantities. As far as we know, only 20 units were manufactured before the project was merged into the RS-101, which was smaller and allowed voice transmissions (phone) in addition to CW. Both the RS-100 and RS-101 show great similarity to the later TAR-224, which was built for the CIA around 1970 by AVCO. In fact, the receiver part of the RS-100 is nearly identical to the receiver of the TAR-224.

  1. The name of the manufacturer is redacted in the original documents, but since the meetings were held in Mountain View, and the manufacturer's name is eight character long with a 'y' in the second position and an 'a' at the end, it is very likely that this was the Electronic Defense Laboratory (EDL) of Sylvania [2].
  2. ARPA/DARPA is a research and development agency of the US Department of Defense, responsible for the development of emerging technologies for use by the military [14].
  3. Without batteries, but with the OS-100 synthesizer installed.

PLEASE HELP — This page shows what we currently know about the RS-100. We are still looking for additional information about this radio set and its successor, the RS-101, in particular the circuit diagrams, the power supply unit and any other ancillaries. If you think you can help us to expand this page, please contact us.
RS-100 with cover
RS-100 radio
RS-100 front panel
OS-100 synthesizer
AU-100 crystal selector
CK-100 keyer, coder and tape cartridge
Keyer, tape and alphabet encoder
RS-100 compared to TAR-100
A
×
A
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RS-100 with cover
A
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RS-100 radio
A
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RS-100 front panel
A
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OS-100 synthesizer
A
5 / 8
AU-100 crystal selector
A
6 / 8
CK-100 keyer, coder and tape cartridge
A
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Keyer, tape and alphabet encoder
A
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RS-100 compared to TAR-100

Features
The image below shows the front panel of the RS-100 radio set, which roughly consists of three areas: at the top right the transmitter, at the bottom right the receiver, and at the left the removable parts. The power source is selected with the power selector at the bottom left, just above the receptacle for the external PS-100 power supply unit (PSU). The unit can be powered by the PSU, a handcranked generator or the internal 12V rechargeable battery. It is turned on with the MODE selector at the top: either the receiver alone, or receiver and transmitter together. Wire antenna and counterpoise (ground) should be connected to the terminals at the top right.

Click to see more

The receiver — at the lower half of the right side — is freely tunable over the entire range, divided over four frequency bands. The desired modulation is selected with the Receiver Mode Selector at the right. For the reception of CW and SSB signals, a Beat Frequency Oscillator (BFO) is present. At the center is a film scale with adjustable centre point, used in combination with the tuning knob.

The transmitter — at the upper half of the right side — is crystal controlled and has four bands. The frequency is controlled by the crystal that is installed on the front panel, or by the selected crystal of the AU-100 crystal selector (not shown here). Alternatively, the frequency can be set with the OS-100 synthesizer, which is installed here in the expansion slot at the top left.

The transmitter is suitable for CW only. Messages in morse code can be sent with the built-in morse key at the centre of the front panel, or with an external key connected to the 3 mm socket to its left. Alternatively, messages can be sent as a burst, using the CK-100 coder/keyer set, which is basically a design variant of the CIA's CK-8 burst equipment. The CK-100 is stowed under the large lid at the centre left. The actual keyer is fitted permanently inside the device.

Power selector
  • HG
    Hand generator
  • HG/BATT
    Internal battery or hand generator
  • PS-100
    External PSU
  • CHG
    Charge internal battery
MODE selector
  • OFF
    Device powered off
  • RCVR
    Receiver on
  • XMTR/RCVR
    Transmitter and receiver on
RS-100 front panel
Transmitter
Receiver
Crystal and crystal selector
OS-100 Synthesizer
AU-100 cyrstal selector installed
Accessory compartments
Power connector
Power selector
MODE selector
Receiver MODE
Battery voltage meter
Internal morse key
CK-100 keyer, coder and tape cartridge
Tape installed on the keyer
Removing the tape
B
×
B
1 / 16
RS-100 front panel
B
2 / 16
Transmitter
B
3 / 16
Receiver
B
4 / 16
Crystal and crystal selector
B
5 / 16
OS-100 Synthesizer
B
6 / 16
AU-100 cyrstal selector installed
B
7 / 16
Accessory compartments
B
8 / 16
Power connector
B
9 / 16
Power selector
B
10 / 16
MODE selector
B
11 / 16
Receiver MODE
B
12 / 16
Battery voltage meter
B
13 / 16
Internal morse key
B
14 / 16
CK-100 keyer, coder and tape cartridge
B
15 / 16
Tape installed on the keyer
B
16 / 16
Removing the tape

History
In 1963 it was decided that the US Central Intelligence Agency (CIA) and the US Defense Advanced Research Projects Agency (ARPA, later: DARPA) would jointly develop an integrated radio set for long-range paramilitary operations, as both services had similar requirements. Intended as a replacement for the ageing modular RS-1 radio set it would be an all-in-one solution for CW (morse code) only, with a built-in medium speed burst keyer, similar to the CK-8 (AN/GRA-71).

Procurement of the RS-100 started on 9 September 1963, with a projected release date of 31 March 1965 and an initial budget of USD 910,701 [7]. It seems likely that the development order was awarded to Sylvania in Mountain View (California, USA). For this price, Sylvania had to deliver 1 engineering model and 10 operational service test models, the first 8 of which were delivered in October 1964. On 24 December 1964, the CIA ordered 10 extra units for USD 207,344.

During an inspection trip to Sylvania on 18 December 1964, it became clear that the budget had been exceeded by USD 116,386, which was within expectation. [7]. Eight of the ten test units had already been delivered and the rest were to follow soon. It became clear that CIA did not find the transmitter part good enough. It was decided to ask AVCO Corporation of Cininnati (Ohio) – who had just developed the 20 Watt RT-66 HF transmitter – to develop a similar one for the RS-100 which did not need a DC-DC converter [8]. A prototype RS-100 was given to AVCO for testing.

At a meeting on 10 March 1965, AVCO's newly developed 20W transmitter was announced. Furthermore, the final procurement of the RS-100 was discussed. The product was as good as finished, but the CIA expressed the view that the RS-100 had become too large and heavy, and that sets like RS-48 and RS-69 (Delco 5300, AN/PRC-64), were preferred. In addition, ARPA stated that the set had been tested by the Combat Development Command, but that they were only marginally interested, and that Special Forces wanted to wait for the new AN/PRC-70 [10].

During the next meeting, on 15 July 1965, CIA notified the board that their requirements had meanwhile changed and that they were now more interested in a smaller radio set, and that they were prepared to drop the 300 wpm burst keyer in favour of voice capability. The RS-101, which had recently been proposed as another possible successor to the RS-1 was considered more suitable. It was therefore decided to stop the RS-100 procurement and use the allocated resources for development of the RS-101. With this decision, the CIA pulled out of the project, allowing ARPA to continue procurement on its own if they so desired. Given the limited interest from the US Armed Forces however, it seems unlikely that further RS-100 sets were produced.

Parts of the RS-100 project were carried over to the new RS-101, such as the OS-100 frequency sythesizer, which became the OS/B-100 [12]. The development of add-ons by other suppliers, such as the HG-100 hand generator, carried on for several more months, until they were also stopped or merged into the RS-101 project [13]. The knowledge from the RS-100 and RS-101 projects was reused a couple of years later, in 1970, in the development of the similar TAR-224.


Parts
RS-100 transceiver
AU-100 crystal selector
OS-100 frequency synthesizer
PS-100 power supply unit
HG-100 handcranked generator
CO-9 burst encoder (alphabetic)
KE/M-8 burst keyer (built-in)
CA-3 tape cartridge
Transceiver   RS-100
The RS-100 is a fully self-contained HF radio transceiver. It can be operated from a built-in rechargable battery and even has a built-in morse key and burst encoder/keyer. It only requires the connection of a suitable antenna and counter poise.

The receiver can be freely adjusted, whilst the transmitter is controlled by a quartz crystal that is installed on the control panel or in the crystal selector. Alternatively, a synthesizer can be installed instead of the crystal selector.

  
RS-100 radio

Crystal selector   AU-100
If the radio has to be operated on a series of predetermined fixed frequecies, a crystal selector could be installed in slot in the upper left corner of the control panel. This Auxiliary Unit can hold up to 40 crystals, arranged as four banks with ten HC-6/U crystals each.

When this option is present, the XTAL selector has to be set to the OS-100/AU-100 position.

 Crystal shapes

  
AU-100 crystal selector

Synthesizer   OS-100
If it is necessary to choose the transmission frequency more freely, the AU-100 crystal selector could also be replaced by the OS-100 frequency synthesizer. It allows any frequency between 2.000 and 11.999 MHz to be selected in 1 kHz steps.

When this option is present, the XTAL selector has to be set to the OS-100/AU-100 position.
  
OS-100 synthesizer

Power supply unit   PS-100
The radio was supplied with a PS-100 power supply unit (PSU), that allows it to be powered directly from the AC mains. The PSU was also used to charge the radio's internal battery.

The PSU should be connected to the uncommon 7-pin receptacle at the bottom left corner of the control panel. If anyone knows what kind of connector this is, please let us know.

The PS-100 is missing from the RS-100 in our collection and no image is currently available.

  

Handcranked generator   HG-100
For use in remote or rural areas where the mains power network is not available, the HG-100 hand generator was used. It can be connected to the connector at the front left of the control panel and can be used to power the RS-100 and charge the internal battery.

The HG-100 delivers 75W of power.

The HG-100 is missing from the RS-100 in our collection and no image is currently available.
  

Burst encoder   CO-8
To minimise the risk of discovery by means of Radio Direction Finding (RDF), the RS-100 is equipped with a CK-100 coder/keyer, which is basically a design variant of the CIA's CK-8 (AN/GRA-71) burst encoder. It is stowed inside the coder compartment of the RS-100.

Messages (preferably encrypted) are recorded onto a CA-3 magnetic tape cartridge by means of the CO-8 hand-operated coder shown in the image on the right. Once complete, they are played back at high speed on the built-in keyer.

 More information

  
CO-8 alphabet coder

Burst keyer   KE/A-8
The keyer of the CK-100 is a design variant of the KE/M-8 motor-operated keyer, shown in the image on the right. Painted green, it is fitted permanently inside the coder compartment of the RS-100 and operated by two toggle switches in the bttom left corner of the compartment.

Messages, recorded on a CA-3 magnetic tape by means of the CO-8 coder, can be played back on the keyer at a speed of 300 wpm. This minimises the on-air time and, hence, the risk of detection and discovery by means of RDF.

 More information

  
KE/M-8 keyer seen from the front

Tape cartridge   CA-3
Messages (preferrably encrypted) are recorded onto this CA-3 magnetic tape cartridge, by means of the CO-8 coder. Once the message is complete, the tape cartridge is removed from the coder and installed on the built-in KE/A-8 keyer.

One tape cartridge is stowed inside the coder compartment of the RS-100. Although one tape cartridge is sufficient for normal operation, spare cartridges were optionally available.

 More information

  
CA/A-3B tape cartridge

RS-100 with cover
Plastic cover
Coded cut-out to ensure that MODE selector is in the OFF position
AU-100 crystal selector
AU-100 synthesizer - rear view
OS-100 synthesizer
OS-100 synthesizer - rear view
Slot for AU-100 crystal selector or OS-100 synthesizer
C
×
C
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RS-100 with cover
C
2 / 8
Plastic cover
C
3 / 8
Coded cut-out to ensure that MODE selector is in the OFF position
C
4 / 8
AU-100 crystal selector
C
5 / 8
AU-100 synthesizer - rear view
C
6 / 8
OS-100 synthesizer
C
7 / 8
OS-100 synthesizer - rear view
C
8 / 8
Slot for AU-100 crystal selector or OS-100 synthesizer

Click to see more

Interior
The RS-100 in housed in a ruggedised die-cast aluminium enclosure that comprises a front panel – to which all internal parts are mounted – and a case shell. The case shell provides a watertight environment for the internal parts, but also serves as a heatsink for the power circuit and the transmitter's power amplifier (PA). For this reason, the 'hot' parts are covered with a silicone heat-conductive paste, to provide thermal contact with the integrated heatsinks of the case shell.

To access the interior of the radio set, 10 hex bolts must be removed from the edges of the front panel, 11 regular screws from the rear, and 2 from the side. This allows the case shell to be removed, after which the interior is exposed.

The receiver is a compact unit which is very similar to the receiver of the later TAR-224 CIA radio set. It consists of various circuits that are separated by metal shields. The transmitter has a different construction and consists of various compartmented circuits that are bolted together. The PA transistor is located in the far corner.
  
Transmitter detail

The image above shows part of the transmitter circuitry, most of which is built around Motorola power transistors. It is uncertain whether the one shown here is the original one developed by Sylvania, or the replacement developed by AVCO between December 1964 and March 1965 [10].

Heat sinks at the rear and side of the enclosure
RS-100 removed from enclosure
Interior
Interior - bottom view
Transmitter (left) and receiver (right)
Interior - bottom side
Power distribution panel
Receiver
Transmitter detail
Transmitter detail
PA transistor
Power circuit
Power circuit - detail
Crystal selector/Synthesizer receptacle
Receiver detail
Receiver detail
D
×
D
1 / 16
Heat sinks at the rear and side of the enclosure
D
2 / 16
RS-100 removed from enclosure
D
3 / 16
Interior
D
4 / 16
Interior - bottom view
D
5 / 16
Transmitter (left) and receiver (right)
D
6 / 16
Interior - bottom side
D
7 / 16
Power distribution panel
D
8 / 16
Receiver
D
9 / 16
Transmitter detail
D
10 / 16
Transmitter detail
D
11 / 16
PA transistor
D
12 / 16
Power circuit
D
13 / 16
Power circuit - detail
D
14 / 16
Crystal selector/Synthesizer receptacle
D
15 / 16
Receiver detail
D
16 / 16
Receiver detail

Connections
Power
For connection of the external PS-100 power supply unit (missing here), an uncommon type of military connector is used. Furthermore, the pin-assignment and the wiring of this connection is currently unknown. If you have additional information, please contact us.

  1. ?
  2. ?
  3. ?
  4. ?
  5. ?
  6. ?
  7. ?
Specifications
  • Device
    Spy radio set
  • Purpose
    Paramilitary operations
  • Model
    RS-100
  • User
    CIA, ARPA
  • Manufacturer
    Sylvania (parts by AVCO)
  • Country
    USA
  • Year
    1964
  • Predecessor
    RS-1
  • Successor
    RS-101
  • Dimensions
    340 x 250 x 150 mm
  • Weight
    7900 g (with synthesizer fitted, without batteries)
  • Quantity
    21
Transmitter
  • Frequency
    2 - 24 MHz
  • Bands
    4 (see below)
  • Modulation
    CW
  • Morse key
    Internal, external, burst
  • Burst
    300 wpm
  • Output
    20 Watt
  • Operation
    Crystal or synthesizer (plug-in)
Receiver
  • Frequency
    2 - 24 MHz
  • Bands
    4 (see below)
  • Modulation
    CW, AM, SSB
  • Output
    Headphones, earpiece
Frequency bands
  • 2 - 3.7 MHz
  • 3.7 - 6.9 MHz
  • 6.9 - 12.9 MHz
  • 12.9 - 24 MHz
Accessories
Surviving units
  • 0007
    Crypto Museum (Netherlands)
References
  1. Nico van Dongen, RS-100 radio set - THANKS !
    Crypto Museum, April 2023.

  2. Pete McCollum, Other CIA radio sets
    Visited 20 April 2023.

  3. Equipment Board Minutes
    CIA, 4 March 1964. SECRET

  4. Contract 151, Task Order 12. Trip Report - CK-100 with ...
    CIA, 9 November 1964.

  5. Trip Report - HG-100 with ...
    CIA, 20 November 1964.

  6. Research & Development Branch, Monthly Report
    CIA, November 1964.

  7. Contract 924, Task Order 7. Trip Report RS-100
    CIA, 30 December 1964.

  8. Research & Development Branch, Monthly Report
    CIA, December 1964.

  9. Research & Development Branch, External Projects Section
    CIA, December 1964.

  10. Agenda Equipment Board, Meeting No. 2-65 (and minutes)
    CIA, 10 March 1965.

  11. Agenda Equipment Board, Meeting No. 5-65 (and minutes)
    CIA, 15 July 1965.

  12. Inspection Report No. 6 - AS/A-8 and OS/B-100 with ...
    CIA, 8 September 1965.

  13. Inspection Report No. 5 - HG-100 with ...
    CIA, 20 September 1965.

  14. Wikipedia, DARPA
    Visited 23 April 2023.
Further information
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Crypto Museum. Last changed: Friday, 26 May 2023 - 05:12 CET.
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