Type 6420, 6421 and 6422 are three coaxial tft(R' Power Heads designed for the measurement of radio frequency signals over an extremely wide range of power and frequency.*' These units are intended for use with the Ml/Sanders type 6460 and 6550B Thermoelectric Power Meters and will measure amplitude and frequency modulated os well as CW signals. The power range of the Coaxial tft Power Heads when used with the Type 6460 extends from 0.03 microwatt on the most sensitive range to 100 milliwatts full scale on the highest power range and from 10 microwatts when used with a type 6550B Still higher powers can be measured using the Ml/Sanders Type 6423 tft Power Head (up to 3 watts) or suitably calibrated couplers or attenuators. Frequency coverage extends from 10MHz to 12.4GHz for each of the models.