Good practice with a spectrum analyzer is to put a 20 dB pad at the input all the time unless you are sure you don't need it for a particular measurement.
It has saved my bacon many times. It also protects the input connector from excessive wear. Didier KO4BB Sent from my Droid Razr 4G LTE wireless tracker. -----Original Message----- From: Chris Wilson <ch...@chriswilson.tv> To: Chris Wilson <ch...@chriswilson.tv>, Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Sun, 09 Dec 2012 5:54 AM Subject: Re: [time-nuts] EIP545A 18GHz counter query > Did do some more reading and I think what I suggest is the right approach. > Band 2 and 3 use the same VCO. So if band 2 is generally working > then its possibly the rf multiplier yig filter mixer diodes etc. But > if the RF detectors show RF then its going to be a much more interesting > issue. > I do not know what sort of test equipment you might have. I have > spectrum analyzers and such. And do agree without extenders that I don't have > its a royal pain. > Regards > Paul. 09/12/2012 11:45 Thanks very much for your input with this, much appreciated. I do have a spectrum analyser, but it's a bit like having a set of surgeons implements. Interesting to have, but needing the requisite skill to use safely :) I can do only the most basic stuff, to be frank I am very wary of blowing the input stage up by doing something daft! I think I follow your train of thought here Paul. But, before seeing your post I did some tests at TP4, to see if the unit was constantly scanning for a signal when on Band 2. here is what I found and saw: I have now refitted the new Q12, and removed the test 1k resistor. OK, the trace from TP4 does different things depending what band it is on. Bands 1 and 3 it just sits there, #1. On Band 2 it gives what appears to be two traces, #2. Changing the timebase gives the other trace I show linked, #3. On bands 1 and 3 only a single trace appears. So Band 2 is doing something different at TP4, with no input signal. Warm Q12 with an input signal to Band 2 and the two traces change to a single trace, #4. Once it cools again the two traces return. Traces: #1 http://www.gatesgarth.com/scope/TP4-band1.jpg #2 http://www.gatesgarth.com/scope/TP4-band2.jpg #3 http://www.gatesgarth.com/scope/TP4-...t-timebase.jpg #4 http://www.gatesgarth.com/scope/TP4-...put-signal.jpg I would need explicit instruction to poke about using the SA. It's an HP 8568B. Thanks again Paul :) -- Best Regards, Chris Wilson. _______________________________________________ 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. _______________________________________________ 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.