CW Water Cooled Amplifier Modules

Modules may be combined to give an arbitrary power level
Frequency and SWR specifications may be customised to suit specialised applications.

Full Power/(Half Power)
Model Freq Range (MHz) P1dB Max SWR
SRF1K1HFPA 5-32/(2.5-50) 1250W 2:1*
SRF2K2HFPA 5-32/(2.5-50) 2500W 2:1*
SRF2K0VHFPA 0-200/(5-250) 2000W 2:1*
SRF1K0VHFPA 0-200/(5-250) 1000W 2:1*
SRF1K0UHFPA 00-500/(50-600) 1000W 2:1*
SRF500UHFPA 00-500/(50-600) 500W 2:1*

*Modules tolerate higher mismatches at lower power with protection based on the magnitude of reverse power.

Module Features

Conservative power ratings. Transistors are operated well within manufacturer limits. Transistors are the latest generation ruggedized types specified to handle 65:1 mismatch. They easily cope with infinite mismatch for short time periods.

The modules feature excellent pulse handling characteristics with fast rise and fall times. Combining is fully isolating to ensure graceful degradation.

Extensive protection systems including:

  • Reverse power
  • Over-drive
  • Over-temperature
  • Over-current
  • Out-of-band

Low level monitoring via I2C of:

  • Temperatures
  • DC currents
  • DC voltages
  • Forward and reverse power
  • Intermediate RF voltages
  • Latched Fault flags

Gain Control via I2C

  • Up to 32db in 0.5dB steps of digital gain control
  • Fine gain control (<0.01dB steps) available via DAC driven analogue attenuator.

PA Rear
PA Front

CW Water Cooled Combiners

Model Inputs Freq Range (MHz) PMAX Typical I.L.
SRF8KCMB82 2x4 2-45MHz 8kW <0.15dB
SRF20KCMB41 4 3-45MHz 20kW <0.1dB
SRF4KLCMB84 4x2 5-40MHz 4kW <0.1dB

Combining is fully isolating to ensure graceful degradation.

Advanced low-loss combining techniques ensure a minimum of power wastage.

Dual Directional Couplers

HF Multi-octave dual directional couplers.


Couplers feature extremely low insertion loss, with excellent sample flatness and directivity over a multi-octave frequency range.

Other frequency ranges and specifications are available on request.

2kW Couplers

CW High Power Filters

High power filters and associated switching are customised to suit the application. These filters are used to routinely achieve harmonic levels 70dB below the carrier.



Typical filter construction is by way of large cross section copper rod inductors and high power, low loss ceramic capacitors.

Typical switch construction utilises vacuum relays rated to over 100 million cycles.

Schach RF has built filters to handle over 8kW of CW power in the HF range.