I am working on development of RF driver input for Klystron amplifier. As usual, pulsed output of PH2931-135S microwave amplifier (input to amplif ier provided after successive amplifications) on spectrum analyzer with 40 dB external attenuation produces normal output of around 13dBm on the Spect rum analyzer without any heating on the attenuator.
But, today I am not getting the reason behind excessive heating produced by the PH2931-135S microwave amplifier (M/A Com) on the external attenuator w ithin 2-3 minutes. After 40 dB attenuation using external attenuator, I get the same 13dBm output display on the spectrum analyzer but the attenuator is heated. Also, there is loading on the Vcc applied to the amplifier (42V Vcc becomes around 33V). Also i have provided Fuse of 1A at the input side of Vcc.
What is the reason behind heating and how to eliminate?