[TenTec] Omni 6+ PLL troubleshooting (was: Help with Omni 6+ rx warble)

[Barry N1EU]

I notice that I can adjust C31 to minimize the warbling, resulting in
a calibration error of 0.7Khz on the main tuning dial.  Could this
because the xtal oven frequency is off?  Trying to bring the freq into
calibration with C31 is introducing too much PLL error?

(I'm really reaching here - any help appreciated - I'd hoping that
folks still work on their Omni 6's).

Thanks & 73,
Barry N1EU

On Sun, Nov 13, 2011 at 10:54 PM, Barry N1EU <barry.n1eu at gmail.com> wrote:
> I've finally got the chance to get the Omni 6+ on the bench.  After
> replacing a very intermittent C31xtal oven trimmer, I started looking
> closer.
>
> I'm getting a rx "warble" now at about a 2hz rate.  If I put a scope
> probe on the logic board PLL chip (U13), I see blips on pins 14 and 15
> (phase/freq detectors) in sync with the rx warble.  I'm pretty
> clueless on PLL circuits.  I'd appreciate any advice on how to proceed
> with the troubleshooting.
>
> Also, where is the 5Mhz PLL Board and the Xtal Osc/LO Mixer Board?
>
> Thanks & 73,
> Barry N1EU
>
> On Wed, Nov 2, 2011 at 9:37 PM, Barry N1EU <barry.n1eu at gmail.com> wrote:
>> I'd appreciate some help troubleshooting a pronounced hitch or warble
>> in the received tone, happening regularly about every 1.5 seconds.  It
>> occurs in cw, lsb and usb.  Please have a listen - this is 10 sec CW
>> plus 5 sec USB tuned to a carrier:
>>
>> http://n1eu.com/omni6_warble.mp3
>>
>> Can anyone provide some helpful troubleshooting tips?
>>
>> Thanks & 73,
>> Barry N1EU
>>
>