Joe, If you have an analog 'scope with delayed sweep, set it up with the main time base showing the 90 MHz signal in a convenient way (say 1 cycle/div) and then use the delay to look at the signal some time later (after the initial trigger) with the modulation on and off. Any phase or frequency modulation should be pretty obvious then. (Note: Use delayed sweep, NOT delayed trigger; i.e., "B starts after delay", not "B triggerable after delay".)
Francis Grosz Original Message --------------------------------------------------------------- It's been a long week and it's only Tuesday. How can I prove that the A3 assembly is, in fact, phase modulating? In other words, how can I prove that the 90 MHz signal from the A3 assembly to J1 on the A4 assembly is phase modulated by the 137 Hz signal? I have looked at the output of the A3 assembly at the cable to J1 on the A4 assembly (A4P1) with an oscilloscope and a spectrum analyzer with Mod On and Mod Off and can see no difference. Likewise, on a functioning unit, I can not see any difference there either. Are there proper ways to set up the scope or SA to focus on this issue? Short of fabricating a 'phase detector', how can I prove that the A3 unit is functioning in my 'problem child' unit. If I have to fabricate a 'phase detector', how easy (or difficult) is that? Thanks, Joe _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.