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VHF/UHF Surveillance Radio Receiver - wanted item

SRR-5 was a solid-state surveillance radio receiver, developed in the early 1960s by the Technical Services Division (TSD) 1 of the US Central Intelligence Agency (CIA) as the successor to the valve-based SRR-4. It covers all frequencies between 50 and 400 MHz and can demodulate AM, FM, CW and modulated CW signals. Although it was a general communications receiver, it was typically used for clandestine operations, in particular for the reception of covert listening devices (bugs).

The receiver measures 30.5 x 27.5 x 10.8 cm and weights just under 9 kg. It can be powered by internal batteries or by the 88-264V AC mains. It features two separate tuners: one for the 50-200 MHz range and one for the 200-400 MHz range, known as the LOW and HI bands.

The desired band is selected with the BAND-switch and each tuner has its own antenna input at the front panel. For short-range reception, the supplied telescopic antenna, mounted at the top right, can be used. Alternatively, an external VHF or UHF antenna, or a car antenna can be used.
SRR-5 receiver as show in [1]

Although it is not marked as such, the SRR-5 is featured in H. Keith Melton's excellent book Ultimate Spy [1], where it is described as a listening post receiver. Although the SRR-5 was commonly supplied with a black front panel, the one in the book has a white front panel and a blue case shell. The SRR-5 was produced in limited quantities from the late 1950s to the mid-1960s and was built at a currently unknown manufacturing company. It was commercially available to approved customers only. The SRR-5 was later complemented by the SRR-8.

  1. The Technical Services Division (TSD) of the CIA was renamed Office of Technical Service (OTS) in 1974 [2].


Image taken from Ultimate Spy, page 118 [1].

  • LOW
    49-204 MHz
  • HI
    204-404 MHz
The following accessories are currently known:

Operating instructions and full service manual
Although Crypto Museum does not have an SRR-5 receiver in its collection, we do have access to its technical manual and som eof its test sheets, which are available for download below [A].

The manual consists of a global description of the device, a description of its operation, a technical description of each sub-circuit, a block diagram, and full circuit diagrams.

 Download the technical manual

SRR-5 Technical Manual
Block diagram
Below is the simplified block diagram of the SRR-5 receiver. At the left are the two independent tuners: one for the LOW band (50-200 MHz) and one for the HI band (200-400 MHz). For each tuner, the frequency of the local oscillator (LO) is 16.5 MHz higher than the received signal.

The model number SRR-5 should not be confused with the AN/SRR-5, which is a radiation monitor used by the US Navy. Please note that AN/SRR-5 is a military designator, whilst 'SRR-5' is a typical CIA designator. The two devices are in no way related.
  1. Operation and Service Instruction Book, Radio Receiver SRR-5
    Includes full circuit diagrams and parts list. Date unknown.

  2. SRR-5 System Test Procedure
    Date unknown. 16 pages.

  3. SRR-5 Data Sheet
    Measurement report for individual SRR-5 receiver. Date unknown. 5 pages.
  1. H. Keith Melton, Ultimate Spy
    First edition 1996. Edition 2015. ISBN 978-0-2411-8991-7. p. 118. 1

  2. Wikipedia, Central Intelligence Agency Directorate of Science & Technology
    Retrieved December 2015.
  1. Image reproduced here by kind permission from Keith Melton, November 2017.

Further information
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Crypto Museum. Created: Friday 25 November 2016. Last changed: Friday, 05 January 2018 - 22:11 CET.
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