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Mason MPR-1
Mini Probe Receiver

The MPR-1 was a miniature portable intercept radio, developed by Mason Engineering Inc. (USA) in 1980, as the successor to the A2 and A3 range of receivers. It is a small modular design that can be enhanced at will. The basic unit consists of the Mini Probe Receiver itself (MPR) and a tiny green spectrum analyzer. A small metal frame was used to hold the two units together. The MPR-1 was succeeded by the improved MPR-5 receiver in 1990, just before Mason closed down.
The MPR-1 can be powered in several ways. When used as a portable device, an external battery or an optional battery cabinet would be used. When used as a table-top device, the supplied mains adapter would be used.

To cover the very wide frequency range of the MPR-1, separate plug-in modules were available for each different frequency band. The image on the right shows a typical MPR_1 unit with a plug-in for the 800-1600 MHz range. In all, 12 different plug-in modules were available, spanning a range from 20 kHz to 10 GHz (!)
Typical view of a 2-piece MPR-1 receiver

The MPR-1 is a very sensitive receiver, capable of finding very small and weak bugs, but the wide frequency span of each module also has its price. When 'sweeping' a room, one has to be careful when using multiple MPR units with the same frequency plug-in, as the radiation of the receiver's local oscillator is strong enough to 'confuse' your colleagues.
The opened suitcase showing its contents Typical 2-piece MPR-1 unit Frontal view of a typical 2-piece MPR-1 unit, consisting of receiver (left) and display (right) MPR-1 with telescopic antenna, ready for use Carrier with 2 units Close-up of the S-meter of the receiver Headphones Adjusting the image

Attaché case
The MPR-1 was usually stored inside a sturdy aluminium case, or in a standard Samsonite briefcase, together with the frequency modules and various other accessories, such as the power supply, cables, antennas, headphones and user manual. The unit in the image below, is packed inside a Samsonite attaché case that was commonly used in those days.
The foam inside the case, has been pre-cut, so that each module can be stored in its own place. The reciver is at the top right. The main power supply is at the top left.

10 frequency plug-ins (tuners) are stored side-by side at the front. They all have the same size and fit nicely into the tuner-slot of the reciever. These 10 tuners (TMPR-1 thru 10), cover the frequency range from 20 kHz to 1.6 GHz. The manual, antenna's, cables and other accessories are stored inside the case lid and inside other compartments of the case (see list below).
MPR-1 in attaché case

An additional plug-in is available for the 1.6 to 10 GHz range. This module (TMPR-11) is larger than the others and will stick out of the front of the receiver when in use. This module is usually stored inside the carrying case to the left of the receiver.
The opened suitcase showing its contents The opened suitcase with its contents Close-up of the suitacase's contents The main unit inside the suitcase The 10 GHz module

The MPR-1 was supplied with a range of accessories, such as power supplies, antennas, cables, connectors, etc. Some of these items were supplied with the set as standard, others were optional extras. Most accessories were stored inside the storage case.

The images below show some of the accessories supplied with our MPR-1. Please note that over time, some items may have been lost or replaced.

Headphones Close-up of an earpiece Telescopic antenna Log-periodic antenna Log-periodic antenna Connector on the log-periodic antenna Antenna extension cable Antenna connector

The MPR-1 was continuously improved over time, leading to small changes in the product name. One example is the MPR-1b which was introduced in 1982. At present, we are uncertain about the MPR-2 and MPR-3, but it is likely that these were special (limited edition) versions of the MPR-1, as the initial 1980 MPR-1 manual lists case inserts for the MPR-1, 2 and 3 (see below).

The basic MPR-1 consists of a receiver (B-8) and the Visual Display (S-8b). The two units were held together by a metal bracket: the so-called 2-pack carrier. In 1982, the range of accessories was extended with a Frequency Counter (FC-5) that was mounted in between the receiver and the visual display. This was called the 3-pack version (MPR-1b). The MPR-1 shown on this page is a 2-pack version. A similar frequency counter was also used with the later MPR-5 receiver.

The tables below shows which parts were present with the MPR-1, either as standard components, or as optional accessories. The two columns at the right show wether it was a standard component with the MPR-1 or the MPR-1b.
Part Model Description 1 1b
30543 B-8 Basic MPR (Mini Probe Receiver)
30545-C TMPR-1 Tuner 20 kHz to 5 MHz plug-in
30546-C TMPR-2 Tuner 5 MHz - 15 MHz plug-in
30547-C TMPR-3 Tuner 15 MHz - 25 MHz plug-in
30548-C TMPR-4 Tuner 25 MHz - 40 MHz plug-in
30549-C TMPR-5 Tuner 40 MHz - 75 MHz plug-in
30550-C TMPR-6 Tuner 75 MHz - 130 MHz plug-in
30551-C TMPR-7 Tuner 130 MHz - 230 MHz plug-in
30552-C TMPR-8 Tuner 230 MHz - 380 MHz plug-in
30553-C TMPR-9 Tuner 380 MHz - 625 MHz plug-in
30590-C TMPR-10A Tuner 625 MHz - 1 GHz plug-in
30554-C TMPR-10 Tuner 1 GHz - 1.6 GHz plug-in
30557 TMPR-11 Tuner 1.6 GHz - 10 GHz plug-in
30544 S-8 Visual Display (Spectrum Analyzer)
30595-D S-8b Visual Display (improved version, MPR-1b)
30541 FC-5 Frequency Counter
Part Quantity Description 1 1b
PWD4163-B 2 Battery Holder
30542 1 PS-16 AC Power Supply
30412-D 1 PS-11A AC Power Supply (MPR-1b)
7838-A 1 Power Adapter 3/2
5654-A 1 European Adapter #1
5655-A 1 European Adapter #2
R6292-A 1 Whip antenna - MPR
30561 1 Microwave Antenna Ass'y
6860-A 1 Gator clip adapter - MPR
6858-A 1 Antenna Cable Extension complete
6857-A 1 Microwave antenna cable complete
30540 1 2-pack carrier (B8/S8)
30588-D 1 3-pack carrier (B8/FC5/S8)
30558-A 1 Long Wire Antenna Ass'y
30568-A 1 Short Wire Antenna Ass'y
30562-A 1 Blocking capacitor
7821-A 1 Attaché Case
7886-A 1 Case Insert - MPR-1
7887-A 1 Case Insert - MPR-2
7888-A 1 Case Insert - MPR-3 (discont'd in 1982)
7967 1 Manual
7807 1 Headset
7832 1 Headset Cord

  1. F. G. Mason Inc., Mini-Probe Receiver, Model MPR-1
    MPR-1 User Manual. November 1980.

  2. F. G. Mason Inc., Mini-Probe Receiver, Model MPR-1b
    MPR-1b User Manual. June 1982.

Further information

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© Crypto Museum. Created: Tuesday 10 March 2009. Last changed: Monday, 22 February 2016 - 11:51 CET.
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