[time-nuts] EIP545A 18GHz counter query

Chris Wilson chris at chriswilson.tv
Sun Dec 9 11:54:01 UTC 2012

> 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,

Once it cools again the two traces return.


#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.

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