The Farran Technology FDB-F8 Gunn Oscillator Bias Supply has been developed as a special purpose low noise Bias Supply for Gunn Oscillators.This requirements is essential to achieve the best spectral peformance from the output of the Gunn Oscillator. This supply is therefore particularly suited for the requirement of phase locking the Gunn Oscillator using a Microwave Source Locking counter. In addition, an internal modulation facility is available which provides 100% AM modulation of the Bias Supply output at a frequency of 1kHz. Bias output connector is SMA and the instrument is housed in a specially designed heat sinking case.