Hello, my Efratom LPRO-101 stopped locking to Rb transition frequency. After reading all the guides I opened the can and disconnected the yellow coax cable from J4 leading to the SRD (step recovery diode). I cannot measure the forward voltage drop with any of my meters. It still has 118pF of capacitance. I measured between the ends of the yellow coax cable when disconnected from the J4 connector. Anybody seen this type of failure? Have I measured correctly? Is there some recommended SRD replacement part-number, that is available today? Any recommendations are welcome. Some other symptoms I see - the lamp voltage is 7.4V, ignites at about 47C. Both heaters are working OK. Current draw is nominal, 1.4A at first and then 0.4A. The 10MHz output frequency varies according to the VCXO control voltage, which swings between 0.5-13V. The voltage (and frequency) up period of the cycle is 35 seconds and the down period takes 120s. I can measure 60 MHz on the can of 2N3553 transistor with more than 56Vpp (this is way to high, isn't it?) and very unstable 60MHz signal 5Vpp on the 2N2369 can. As the 60MHz peak-to-peak voltage on 2N3553 is higher than 18Vpp, I assume maybe same other parts are broken that lead to this high P-P voltage that broke the SRD. .md