Spy radio
Burst encoders
Rohde & Schwarz
• • • Donate • • •
   Logo (click for homepage)
TSCM equipment

F.G. Mason Engineering Inc. was an American manufacturer of technical surveillance and counter­measures equipment (TSCM), known for its fine range of bug-finding receivers. The company was founded on 20 November 1961 by Francis (Frank) G. Mason, who also developed all equipment during the founding years. The company was dissolved in the early 1990s after a bribe scandal.

Mason developed a range of TSCM equipment and was for more than 30 years one of the most respected key suppliers of TSCM equipment to law enforcement agencies all over the world. The range consisted of suitcase receivers, such as the A-2 and A-3, and portable receivers, like the MPR-1 and the MPR-5. The range of receivers was complemented by the PACMR-1; a three-piece programmable audio receiver that is sometimes referred to as the predecessor of the popular REI OSCOR range that was introduced in the 1990s.

Apart from TSCM receivers, Mason also developed a range of telephone analyzers, such as the TT-4 and TT-6, that were used by governments to check (analogue) telephone lines for bugs and wire tapping. All equipment was hand-build at the Mason facilities in Fairfield (Connecticut, USA) by some 60 employees, and most equipment was developed by company owner Mason himself.

 History of Mason Engineering Inc.

Mason equipment on this website
Semi-portable bug finder, made for the US Army
Portable modular intercept receiver A2
Complete integrated intercept receiver A2C-S Portable modular intercept receiver A3B Complete integrated intercept receiver A3C-S Mini Probe Receiver MPR-1 Mini Probe Receiver MPR-5 Programmable Audio Countermeasures Receiver

Portable Receiver A-2
The A-2 was the first publicly available modular TSCM bug detector, developed by Frank Mason around 1964. Based on the A-1, which was built exclusively for the US Army, the A-2 was able to find radio bugs in the 2 kHz to 2 GHz range.

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

 More information
Mason A2 receiver

Integrated receiver A-2CS
The A-2CS is functionally identical to the A-2, 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 or system.

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

 More information
Mason A2C-S receiver

Semi-portable receiver A-3B
In 1968, Mason started the development of the successor to the A2-series, the Portable Receiver A-3, which was introduced in 1971.

The A-3 can be considered an improved version of the A-2. The scope is mounted in the lid of the case and can be viewed through a mirror. The unit shown here is the later A-3B.

The A-3 receiver was very popular with security agencies world-wide. It's use by the US government was confirmed in 2008 [5].

 More information
Mason A-3B receiver

Integrated receiver A-3CS   wanted
In the early 1970s, an improved version of the self-contained A-2CS 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 A-3CS 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

PACMR-1 Receiver   wanted
PACMR-1 was a programmable audio counter­measures receiver, developed in the late 1980s and mainly used by US law enforcement and intelligence agencies. The large 3-piece system can be seen as the predecessor of the popular REI OSCOR range that has dominated the TSCM market throughout the 1900s and 2000s.

We are currently awaiting additional information on the PACMR-1, which will eventually become available on this page.

 Sneak preview

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. So far, we haven't received any reports from someone who has actually seen the Mason A1, which appears to have been made especially for the US Army [6].
  2. The MPR-4 was probably never released as an official product. Only prototypes have been reported, such as the one with serial number 4 that was offered on eBay in December 2001 [6].

  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.

  6. Kevin D. Murray, Mason Enigineering Model A-2CS, etc.
    Forum discussion on spybusters.com. 16 Jan 2005.

Further information

Any links shown in red are currently unavailable. If you like the information on this website, why not make a donation?
Crypto Museum. Created: Friday 14 August 2009. Last changed: Tuesday, 26 July 2016 - 07:23 CET.
Click for homepage