CMA-100 Countermeasures Amplifier

 The Countermeasures Amplifier (CMA-100) is a high gain audio amplifier used to detect and identify certain types of surveillance devices attached to building wiring such as telephone wiring,
LAN and server systems, AC Power, Alarm wire etc.

The CMA-100 is designed to provide flexible features and will
prove to be very useful in many situations.


The CMA-100 has a balanced input impedance of 50K ohm, can withstand being attached to live power lines with voltages up to 250V, and provides up to 115dB of gain.

Additionally, the CMA-100 utilizes a unique AGC that has 105 dB of control. Signals as large as 31V peak-peak can still be monitored with minimal distortions. Manual gain control can be set to 0, 25, 50, 75, or 100 dB. Filters can be positioned to FLAT, LOW PASS, HIGH PASS, or BAND PASS.

CMA-100 Advantages

  • This multifunctional amplifier has a built in AC/DC digital voltmeter, selectable audio filters, and an extremely wide dynamic range.
  • Balanced and Unbalanced high impedance inputs provide connectivity to to a variety of suspect wiring.
  • The CMA-100 also provides a bias voltage adjustable between -14.5V and +14.5V DC that is used to activate possible devices that are voltage or current sensitive. The bias generator is compatible with most types of line conditions.
  • All of these functions employ a sophisticated automatic gain control circuit that is superior to most audio amplifiers.


  • Input Impedance: 50k balanced
  • Common Mode Rejection: >75dB
  • Maximum Usable Input: 31V p-p
  • Preamp Auto attenuator: 0 to -40 dB ( with overload warning LED )
  • Manual Gain Control: 0, 25, 50, 75, 100 dB
  • Headphone Gain Control: 0 to 15 dB
  • Maximum System Gain: 115 dB manual mode, 120 dB in Auto Mode
  • Frequency Response: 25 Hz to 44Khz
  • High Pass Filter: 320Hz to 44kHz
  • Low Pass Filter: 25Hz to 3.2kHz
  • Band Pass Filter: 320Hz to 3.2kHz
  • Headphone Audio Output
  • Line-Out Audio Output: 600
  • Bias Control: 0 to +/-14.5V DC, 5mA max ( over current protected, input impedance is reduced to 3.6k ohms when bias is active )
  • Digital Voltmeter: 3.5 Digit, auto zero, auto polarity, +/-199.9V AC/DC
  • Power On/Low Battery LED ( LED off @ 6.0V )
  • Battery: 9V Alkaline ( 5 - 30 Hrs typical run time )
  • Maximum Input voltage: 250V AC/DC
  • Leakage Resistance to Case: >10M
  • Size: 7.3"(184.4mm) x 2.75"(69.8mm) x 1.75"(44.5mm)
  • Weight: 12.1 oz (343g)

some specifications subject to change.