[time-nuts] EIP545A 18GHz counter query
paulswedb at gmail.com
Fri Dec 7 14:52:43 UTC 2012
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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