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Mason A-2CS
Integrated surveillance receiver

The A-2CS was a self-contained surveillance receiver designed and built by Mason Engineering Inc. in Fairfield (Connecticut, US) in the late 1960s. It is essentially a an slightly improved Mason A-2, of which all plug-in units and accessories were integrated in a single aluminium container.
 
The image on the right shows a typical A-2CS unit, as it was used by various agencies for bug-finding and surveillance tasks. Behind the top lid of the case (taken off here) is the control panel, containing all connections, controls and read-outs. The unit can be powered by the internal battery (DC), or directly from the mains (AC).

Unlike with the A2, no patch cables are required to operate the A-2CS. Instead, all units are wired internally, and a built-in selector switch at the bottom centre is used to select the required module and, hence, the desired frequency range.
  
Mason A-2CS front panel

On the A-2, the green phosphor CRT display can be used for two purposes: as an HF spectrum analyzer and as an LF (audio) analyzer. In the A-2CS, a seperate CRT display is used for either task, so that HF and LF spectrum can be monitored simultanously. To cover the wide frequency range of the unit, several antennas were supplied with the set. In the image above, a telescopic antenna is connected at the top left of the receiver. For field-use, a rechargable battery was hidden inside the top lid of the aluminium case. It was connected to a socket at the left.

Please note that, compared to the A-2, the frequency scales are missing from the individual frequency modules. Instead, the unit is equipped with a digital frequency readout (right behind the telescopic antenna). Apparently, this was not such a good idea, as the scales would return on the later A-3CS model. In addition, the A-3CS had connections for extra antennas and for the portable MPR-5 surveillance receiver, allowing a second demodulation of subcarrier (SC) signals.

According to one source [1], only around 240 units were ever built, 220 of which were sold to the US Government. The A-2CS featured on this page however, has serial number 333. It was in use at the USIA for many years, until it was decomissioned when the agency closed in 1999.
 
The closed aluminium case Mason A2C-S complete unit with the lid removed Mason A2C-S front panel Close-up of the 2 oscilloscopes and some frequency modules Close-up of the frequency counter and some frequency modules Close-up of the oscilloscopes and the field strength indicator The aluminium lid and the number lock The battery pack (and cable) hidden inside the lid of the case

 
Wanted
We are currently looking the for User Manual of the A2C-S and, if possible, also for a Technical Description or a Service Manual. If you have any of these available, please contact us.
 
References
  1. Granite Island Group, Used equipment price index list
    Retrieved October 2012.

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Crypto Museum. Created: Saturday 27 February 2010. Last changed: Monday, 22 February 2016 - 11:42 CET.
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