Spy sets
Burst encoders
Logo (click for homepage)
Mason Engineering Inc.
F.G. Mason Engineering Inc. was an American manufacturer of technical surveillance and counter measures equipment (TSCM). They are best known for their range of bug-finding receivers. The company was founded in the early 1960s by Francis (Frank) G Mason, who also developed all equipment in the early years. The company was closed in the early 1990s after a bribe scandal.
The company developed a wide range of TSCM equipment, and for more than 30 years, they were one of the key suppliers to governments all over the world. Well-known bug finders were developed, such as the Mason A2, the A3 and the MPR-1 shown in the image on the right. Later versions, such as the MPR-5 are still used widely today by specialised TSCM companies around the world.

Mason Engineering Inc. was based in Fairfield, Connecticut (USA), where all equipment was assembled by approx. 60 employees.
Mason MPR-1 receiver in use

In the early 1990's, the tide turned against Mason, when both the company and Frank Mason himself were prosecuted and convicted for breaking the FCPA [1]. Apparantly, Frank Mason tried to bribe West German Government officials when trying to win a large contract with the West German Military Intelligence Service (MAD) [2]. Both the company and its sole share holder were sentenced to a USD 75,000 fine and five years probation. Fruthermore they had to restitute USD 160,000 to the German government [3]. Shortly afterwards, Mason Inc. closed its doors.

Despite all this, Mason can be considered one of the pioneers of TSCM equipment and his receivers are beautiful examples of clever engineering; way ahead of their time. According to a former Mason employee [4], most of the design and engineering work was carried out by Frank Mason himself, and all electronic and mechanical parts were built in-house.

Mason equipment covered on this website:
Portable modular intercept receiver A2 A2 Complete integrated intercept receiver A2C-S A2C-S Portable modular intercept receiver A3B A3B Complete integrated intercept receiver A3C-S A3C-S Mini Probe Receiver MPR-1 MPR-1 Mini Probe Receiver MPR-5 MPR-5

Portable Receiver A2
As far as we know, the A2 was the first modular receiver developed by Frank Mason in the mid-1960s. It was intended as a bug-finding device.

Visually, it is one of the most interesting receivers of the Mason family. The receiver is stored inside a leather suitcase, together with all of the accessories and plug-in units (see below).

 More information
Mason A2 receiver

Complete Receiver A2C-S
The A2C-S is functionally identical to the A2, but rather than supplying a series of separate plug-in modules and accessories, all relevant components have been combined in an all-in-one solution.

Instead of using patch cables to select the required frequency range, a built-in selector switch is used.

 More information
Mason A2C-S receiver

Portable Receiver A3B
In 1968, Mason started the development of the successor to the A2-series, the Portable Receiver A3, which was introduced in 1971.

The A3 can be considered an improved version of the A2. The scope is mounted in the lid of the case and can be viewed through a mirror. The unit shown here is the later A3B.

The A3 receiver was very popular with security agencies world-wide. It's use by the US government was confirmed in 2008 [5].

 More information
Mason A3B receiver

Complete Receiver A3C-S
In the early 1970s, an improved version of the self-contained A2C-S receiver was introduced. It was housed in a similar case, but contained a number of important improvements over its predecessor. All plug-in units are permanently built-in and wired.

Some versions of the A3C-S can use the later MPR handheld receivers as input, allowing subcarrier signals to be demodulated.

 More information

Mini Probe Receiver MPR-1
The MPR-1 was developed around 1980. It's 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 phosphor display bolted onto it.

In all, 12 different plug-in frequency modules were available, spanning a very wide frequency range from 20 kHz to 10 GHz (!)

 More information
Mason MPR-1 Mini Probe Receiver

Mini Probe Receiver MPR-5
The MPR-5 was the last member of the Mason family, developed in the 1990s, just before Mason had to close their doors. It resembles its predecessor, the MPR-1, but contains a number of improvements.

Like the MPR-1, it was usually supplied in an unobtrusive briefcase. The MPR-5 is still used widely today.

 More information
Mason MPR-5 Mini Probe Reciever

Product line
Below is a list of known equipment from the Mason product line. We have no idea whether this list is complete, but if you happen to know an item that is not listed below, please contact us.
  1. USA, Department of Justice, Int'l Agreements Relating to Bribery of Foreign Officials
    Website. Retrieved June 2009.

  2. United State District Court (New Haven), US v. F.G. Mason Engineering Inc.
    Charges against Mason. No. B-90-29. 25 June 1990.

  3. United States vs. F.G. Mason Engineering Inc. and Frank G. Mason
    Mason found guilty of violating the FCPA.
    US v. F.G. Mason Eng'g Inc., No. B-90-29 (D. Conn. 1990). p. B-14.

  4. Personal correspondence with a former Mason employee
    Crypto Museum, January 2009.

  5. Scientific American, Spying on the Spies
    State Department shows off Cold War-era electronic evesdropping gadgets.
    Larry Greenemeier, 22 July 2008.

Further information

Any links shown in red are currently unavailable. If you like this website, why not make a donation?
© Copyright 2009-2013, Paul Reuvers & Marc Simons. Last changed: Thursday, 16 May 2013 - 08:24 CET
Click for homepage