[time-nuts] EIP545A 18GHz counter query
paulswedb at gmail.com
Sat Dec 8 01:20:26 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
On Fri, Dec 7, 2012 at 9:52 AM, paul swed <paulswedb at gmail.com> wrote:
> So you also must run the gatesgarth website. I was thinking there might be
> other good tidbits. The EIP manual was nice. Good job on the control signal.
> I had a chance to reread the theory of operation yesterday (Well parts)
> and if band 2 is now working by cheating at least, then it would be
> interesting to look at band 3 and see whats going on.
> There seems to be 3 variables that control operation. 1 you have
> experimented with the next is the band 2 or band 3 selection and then the
> 3rd is how the system searches for a signal in either band.
> This seems to be a diode detector in the front end and a diode detector in
> the IF. When a signal is detected at the front and the signal in the IF is
> larger the system says I have a signal in the correct down conversion band.
> The operational logic diagrams are far more clear.
> So the trick in band 3 would be to look at the IF rf diode and see if it
> ever has a voltage. That would give a hint as to what direction to look in.
> Sure you could look at the LO with a spectrum analyzer and see if it was
> correct also. You just might not have one. :-)
> On Fri, Dec 7, 2012 at 5:22 AM, Chris Wilson <chris at chriswilson.tv> wrote:
>> > This is where I am now, I hope the above makes some sense if
>> > viewed with the service manual and the schematics. Thanks.
>> 07/12/2012 10:17
>> Latest update:
>> Removed Q12 from board A109 and put a 1k resistor across vacant
>> emitter and collector board holes, thus putting 12 volts into the
>> mixer to switch it externally. Counter now works perfectly on Band 2
>> and I followed the signal path from R2 / R3 junction (wrong impedance,
>> but a reference nonetheless) through to the anode of CR3.
>> Hopefully self explanatory with regard to file names, scope patterns
>> are at http://www.gatesgarth.com/scope/scope.zip
>> Pretty stuck as to where to go next now.
>> Best Regards,
>> Chris Wilson.
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