Adrian,
Be aware of what is mentioned before by Garey - K4OAH. When changing the pots,
the 10V-DC will not be the same voltage as before. Changing that voltage
requires a full alignment of the TR7. So, before you start removings the pots,
warm up the TR7 for a minute or 10. Than measure the 10V-DC with a digital
voltmeter as accurate as possible and write down the value on a piece of paper.
After that you can replace the pots and ,after warming up the TR7 again, adjust
the 10V-DC voltage to exactly the same value as measured before. After that you
can re-align the other pots as described in the manual.
This is not a guarantee that the TR7 needs a complete aligment yet, but I think
it's the best way to replace the pots.
Good luck,
Carel - PA0CMU.
> From: [email protected]
> To: [email protected]
> Date: Fri, 18 Dec 2009 09:23:34 +0000
> Subject: Re: [Drakelist] TR7 VFO Problem ?
>
> Hello all
>
> I have the Service Manual and have it printed out.
>
> To confirm the symptoms, on 21 and 28MHz the counter settles around
> 33.030MHz and 17.206MHz on all other bands. Connecting an antenna I can
> "hear" my signal generator on thes frequencies (sweeping the generator
> through the 33 and 17MHz frequencies). With an external source the counter
> works fine.
>
> So the synthesizer doesn't appear to be locking. I have cleaned the Molex
> connectors. My next course of action is to replace the pots on the voltage
> control board for multiturn ones, and re-align the voltages etc, and then
> re-check the synthesizer board again.
>
> Thanks all for the help, so far !
>
> Adrian MW1LCR
>
>
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