REI CMA-100 Countermeasures Amplifier

The REI CMA-100 Countermeasures Amplifier is a high gain audio amplifier used to check various sets of building wiring such as alarm wire, AC power, telephone wiring and LAN and server systems in order to detect and locate specific forms of surveillance devices.

The built-in automatic gain control circuit in the REI CMA-100 Countermeasures Amplifier, is more sophisticated than that of most audio amplifiers. The unique automatic gain control (AGC) built into the REI CMA-100 has 105dB of control. The CMA-100 also allows for manual gain control, with options for the operator to set the gain at 0, 25, 50, 75 or 100 dB.

With 50K ohm of balanced input impedance, the CMA-100 Countermeasures Amplifier is able to endure being attached to live power lines with voltages of up to 250V and can provide gain up to 115dB. The REI CMA-100 is also able to monitor, with minimal distortions, signals as large as 31V peak-peak. Band pass, high pass, low pass and flat filters are built into the CMA-100 and can be selected via a dial on the CMA-100’s unit.

Please Note: QCC Global Ltd only supplies accredited TSCM training services to Government, Military, Law Enforcement, CPNI & Commercial Partnership clients.

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REI CMA-100 Specifications


  • No filtering: 25 Hz – 44Khz
  • High pass filter: 320Hz – 44kHz
  • Low pass filter: 25Hz – 3.2kHz
  • Band pass filter: 320Hz – 3.2kHz

Frequency Response

  • Unit dimensions: 7.3 x 2.75 x 1.75 in (185.4 x 69.8 x 44.5 mm)
  • Unit weight: 12.1 oz (343 g)

Digital Voltmeter

  • 3.5 Digit, auto zero, auto polarity, +/-199.9V AC/DC

Automatic Gain Control

  • Manual gain control: 0, 25, 50, 75, 100 dB
  • Headphone gain control: 0 – 15 dB
  • Maximum system gain: 115 dB Manual mode, 120 dB in Auto mode

Bias Control

  • 0 to +/-14.5V DC, 5mA max (over current protected, input impedance is reduced to 3.6k ohms when bias is active)

Maximum Input Voltage

  • 250V AC/DC
  • Leakage resistance to case: >10M Ω

Input Impedance

  • 50k Ω balanced
  • Common mode rejection: >75dB
  • Maximum usable input: 31 Vp-p
  • Preamp auto attenuator: 0 to -40 dB (with overload warning LED)


  • Headphone audio output
  • Line-out audio output: 600 Ω
  • Power on/low battery LED (LED off @ 6.0V)
  • Battery: 9V Alkaline (5 – 30 hours typical run time)