Hello Knut,
Many years ago I had a similair problem like the one you describe,
resoldering all the components on the PLL board (81599) did the job.
73 Gert, PA3AAV
----- Original Message -----
From: <knut.baczko@t-online.de>
To: <tentec@contesting.com>
Sent: Sunday, April 04, 2010 3:01 PM
Subject: [TenTec] OMNI VI VXCO help needed DK5AD
>
> Hello,
> hopefully somebody is able to help me.
> I have an OMNI VI, model 563. Since some time there was a chirp on 17m
> and 12m did not work at all.
> I checked the 10.000MHZ reference frequency form the crystal oven at
> connector 88 and it seemd ok.
> Anyhow I wanted to test and turned trimmer capacitor 31. This had no
> frequency effect. At that time I did not know that I have already the
> VXCO installed by TT when the rig was at the factory several years ago.
> But after changing capacitor 31 the follwing happened what I dont
> understand at all. After switching off and on again, no signals could be
> heard on any band. A complete reset did not help. Only when one switches
> the rig and power supply off for several hours and back again the
> receiver seemed to work ok. But on transmitting in CW I got reports that
> my tone was very bad. I checked my transmitted signal with an
> oscilloscop and it looked ok. What I found out later was that the Omni
> was receiving but only on one frequency depending on the band chosen
> despite that the frequency readout changed when turning the VFO knob.
> For more testing I tuned capacitor 31 again. After that I am stuck now
> i.e. the receiver wont tune at all to a different frequency even after
> the rig is switched off for longer time.
> For further information it looks like that at TT the original crystall
> oven was disabled by removing resistor R2 (150 OHM) which carries its
> supply voltage. What I dont understand is why capacitor 31 still seems
> to have a fuction though the oven is disabled? Why does it take so long
> that the receiver is working again when the power is swiched off
> completely? Why is the transmitted signal so bad? And off course what
> can be done to have the OMNI working again.
> I still like the OMNI VI very much because in the past it was the most
> reliable rig especially in contests. Other newer more computerized rigs
> have sometimes problems with the high transmitted HF power present in my
> shack.
> Knut DK5AD/OE2BZL
>
>
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