Not sure if this microwave power sensor is repairable. It’s an HP P468A waveguide thermistor mount for 12.4 to 18 GHz. It was bugging out, and I’ve rejuvenated one of these before (using the guidelines in the manual) but it didn’t work this time. I’m puzzled by the mechanics of this, what the adjustment screw actually does, and why is it attached to a small metal block which is maybe held with conductive paste? It’s supposed to finely match the inner and outer thermistors: one is in the waveguide and the other is inside the housing as a reference. The waveguide thermistor is heated by the RF signal, and the power meter detects this, via a bridge circuit which tries to balance the current in each thermistor.

The wonders of 1970s microwave tech. We explored space with this stuff.

#hamradio #amateurradio #microwave #electronics