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Micro-Tel PR-700
Surveillance Receiver - under construction

The PR-700 was a surveillance receiver, developed and produced in the late 1970s by Micro-Tel Corporation in Hunt Valley (Baltimore, US). The receiver covers a frequency range from 3 kHz to 2000 MHz (2 GHz) and was intended for radio surveillance and monitoring applications.
The receiver has a fully digital frequency control and readout, with a resolution of 10 Hz or 100 Hz. It allows both fast scanning and incremental scanning, for rapid wideband sweeps. At the left is a built-in panoramic display that can show the demodulated signal on-screen simultanously.

Like most other products developed by Micro-Tel, the PR-700 was initially intended for the various agencies of the US Government and the Department of Defense (DoD). The image on the right shows a typical PR-700B. It is housed in a 4U 10" rackmount case with a typical mint color.
Micro-Tel PR-700 surveillance receiver

In order to allow operation of the PR-700 in various parts of the world, the built-in Power Supply Unit (PSU) is suitable for the 115V and 230V AC mains (50 or 60 Hz). Alternatively, it can be powered by an external 24V DC source, allowing it to be used inside a (military) truck or van.

The first developments of the PR-700 started in the late 1960s, but it wasn't until the mid-1970s before something usable was produced. The PR-700A appeared on the market in the late 1970s, followed in the early 1980s by the slightly more versatile PR-700B. The latter could be controlled by a computer and offered more room for expansion. Both models could be expanded by installing one or more options, with the PR-700B being the more expandible one.

The PR-700 was regarded the state-of the art 'spook' receiver of the 80s and 90s, and remained in production for many years. Even today they are highly valued as measurement receivers, although their place as surveillance receivers has been taken by Software Defined Radio (SDR).
The receiver can demodulate AM, FM, CW, LSB and USB in 3 kHz and 15 kHz bandwidths, and AM, FM and CW in 150 kHz and 2 MHz bandwidths. The demodulated signal is available on a separate output socket at the rear. Also available on a separate socket is a 20 MHz wideband IF signal.

Manual tuning is achieved by using four UP/DOWN push-buttons on the front panel, plus a small rotary dial for fine tuning. The rotary dial is connected to an internal optical encoder, that provides a tuning resolution of 10 Hz.

AM, FM, SSB and CD demodulation of subcarrier signals is also possible. The CRT can display a sub-carrier spectrum of 200 kHz. In subcarrier mode, the subcarrier TUNE control can be used to set a marker. When terminating the SCAN mode, the demodulated subcarrier signal can be fine-tuned and heared via the audio output. A variable Beat Frequency Oscillator (BFO) allows demodulation of single or double sideband signals (SSB).
Modes of operation
  • SCAN
    In SCAN mode, the entore frequency band is displayed on the monitor (CRT), whilst a movable marker allows the operator to select a particular signal for further analysis.

    In Variable Scan mode (VAR SCAN), the CRT displays an adjustable sector up to 10% of frequency centered on the marker.

  • MAN
    In Manual Mode (MAN), the built-in synthesizer becomes operational. In this mode, the CRT has adjustable widths up to 2.5 MHz, and simultaneous audio output is provided in the switch-selected bandwidths.

The PR-700 can be used as a complementary demodulator for the MSR-901 and the MSR-902 precision microwave receivers (1-18 GHz).

The panoramic frequency display of the PR-700 can be used as a display for the MSR receivers. In addition, the PR-700 can be used as a second demodulator for the MSR-901/902, allowing subcarrier bugs to be intercepted.

 More about the MSR-901
Micro-Tel MSR-901

  • Multi-Mode Tuner
  • Fast Scan and Incremental Scan for rapid wideband sweeps
  • Digital frequency control and readout
  • 10 Hz or 100 Hz resolution
  • Panoramic Display with simultaneous Sweep and Demodulation
  • Selectable bandwidth: 3 kHz, 15 kHz, 150 kHz, 2 MHz and 20 MHz
  • Subcarrier receiver tunable from 10 kHz to 200 kHz
  1. Selectable Pan Video Bandwidths of 3, 10 or 35 kHz on front panel.
  2. Not assigned.
  3. All rear panel BNC connectors and antenna inputs to the top and 3" extra depth for additional options. 1
  4. 5 audio bandswidths (rather than 4): 3, 15, 75, 300 kHz and 2 MHz.
  5. 21.4 MHz IF output. 2
  6. 1.65 MHz IF output. 2
  7. Remote control is subcarrier receiver. 2
  8. Selectable subcarrier bandwidths of 6 and 35 kHz.
  9. Front panel threshold and squelsh.
  1. PR-700B only.
  2. PR-700B with option 3 only.
  1. Micro-Tel Corporation, Operating & Maintenance Manual for PR-700B Receivers
    An Adams-Russell Company. March 1982.

Further information

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