20T4G18 Amplifier Research TWT Amplifier



  • Power (fundamental), CW, @ Output Connector: Nominal: 42 watts; Minimum: 20 watts
  • Linear @ 1dB Compression: 10 watts minimum
  • Flatness: ±9 dB maximum, 4.2-18 GHz; ±5dB maximum, 8.0 - 18 GHz
  • Frequency Response: 4.2-18 GHz instantaneously
  • Input for Rated Output: 1.0 milliwatt maximum
  • Gain (at maximum setting): 43 dB minimum
  • Gain Adjustment (continuous range): 35 dB minimum
  • Input Impedance: 50 ohms, VSWR 2.0:1 maximum
  • Output Impedance: Output power foldback protection at reflected power exceeding 20 watts. Will operate without damage or oscillation with any magnitude and phase of source and load impedance. May oscillate with unshielded open due to coupling to input. Should not be tested with connector off.
  • Modulation Capability: Will faithfully reproduce AM, FM, or pulse modulation appearing on the input signal. AM peak envelope power limited to specified power.
  • Noise Power Density: Minus 80 dBm/Hz (maximum); Minus 90 dBm/Hz (typical)
  • Primary Power: 99-260 VAC, 50/60 Hz single phase, 600 VA maximumn
  • Cooling: Forced air (self-contained fans), air entry and exit in rear

Harmonic Distortion (at 20 watts): 

  • 4.2-4.5 GHz; Minus 0dBc maximum, Minus 1dBc typical
  • 4.5-5 GHz; Minus 1dBc maximum, Minus 2dBc typical
  • 5-7 GHz; Minus 2.5dBc maximum, Minus 4dBc typical
  • 7-10 GHz; Minus 5dBc maximum, Minus 9dBc typical
  • 10-12 GHz; Minus 8dBc maximum, Minus 12dBc typical
  • Above 12 GHz; Minus 20dBc maximum, Minus 30dBc typical


  • RF input: Type N female on rear panel
  • RF output: Type TNC female on rear panel
  • RF output sample port: Type N female on rear panel
  • GPIB: IEEE-488-(f)
  • Interlock: DB-15 female on rear panel

The Amplifier Research Model 20T4G18 is a self contained, forced air cooled, broadband traveling wave tube (TWT) microwave amplifier designed for applications where wide instantaneous bandwidth, high gain and moderate power output are required. A reliable micro TWT provides a conservative 20 watts minimum at the amplifier output connector. Stated power specifications are at fundamental frequency.

The amplifier's front panel digital display shows forward and reflected output plus extensive system status information accessed through a series of menus via soft keys. Status indicators include power on, warm-up, standby, operate, faults, excess reflected power warning and remote. Standard features include a built-in IEEE-488 (GPIB) interface, 0dBm input, VSWR protection, ga in control, RF output sample port, plus monitoring of TWT helix current, cathode voltage, collector voltage, heater current, heater voltage, baseplate temperature and cabinet temperature. Modular design of the power supply and RF components allow for easy access and repair. Use of a switching mode power supply results in significant weight reduction.

Housed in a stylish contemporary cabinet this unit is designed for benchtop use but can be removed from the cabinet for rack mounting. The Model 20T4G18 provides readily available RF power for a variety of applications in Test and Measurement, (including EMC RF susceptibility testing), Industrial and University Research and Development, and Service applications.

More Information
ManufacturerAmplifier Research
Power20 W
Frequency18 GHz
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