Chris TP4 is not all that helpful its a control signal. So let me back up for a minute. What are we troubleshooting? I was thinking band 2 was semi working and you still had a totally dead band 3. My comments have been around trying to see what was going on with 3. Other comment. I think we should take this offline. Most likely driving time-nuts nuts. :-) Do you use skype? Regards Paul
On Sun, Dec 9, 2012 at 11:29 AM, paul swed <paulsw...@gmail.com> wrote: > Didier is 100% correct though I use a 10 db pad for exactly the same > purpose. You have to be careful. In your case there is a +28 db power amp > that feeds the yig mixer in the 545. That would destroy the spectrum > analyzer frontend. In fact if measuring that component you would want 30 db > of loss using a 2 watt pad. Most spectrum analyzers run in the 0 to +5 or > so db range. > > All of that said I actually have to look at your other comments to make > some sense of what you are seeing. > Regards > Paul > WB8TSL > > > On Sun, Dec 9, 2012 at 7:22 AM, <shali...@gmail.com> wrote: > >> 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. >> > > _______________________________________________ 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.