[TenTec] Omni VI opt 3.... PLL problem

[Jim Goudie]

Pete,

Thanks!  I saw a reference today stating that these boards “in the oven” often have solder joint problems, which makes me think that my be heat related, as well.

I appreciate this additional information.  I only have a 20 mhz scope, but I know people!  ;-)

Thanks again!!
Jim  AF3Z

Jim Goudie   —  jagoudie at comcast.net
610 Kraybill Church Rd
Mount Joy, PA 17552

> On Jan 28, 2022, at 1:43 PM, Peter Bertini <radioconnection at gmail.com> wrote:
> 
> *To*: tentec at contesting.com
> *Subject*: Re: [TenTec] Omni VI warbling sound
> *From*: Peter Bertini <radioconnection at gmail.com>
> *Reply-to*: Discussion of Ten-Tec Equipment <tentec at contesting.com>
> *Date*: Wed, 26 Dec 2018 09:15:59 -0500
> *List-post*: <mailto:tentec at contesting.com <tentec at contesting.com>>
> 
> That warbling   can also be caused by a HFO crystal that is trying to phase
> lock to the master oscillator. The PLL will sweep the oscillator loop
> voltage trying to achieve a locked condition.
> 
> I've had problems with a few (three) of my Omni VI rigs developing problems
> with the oscillators on the 81595 LO Mixer Board. If the problem is not in
> your VFO PLL,  look at the lock signal on Pin 11 of U13 on the CPU board.
> It should be a very narrow negative pulse (100 MHz scope, fastest scan
> rate) and stable.  Oscillators are adjusted for minimal pulse width.  If an
> oscillator is out of lock, you will see a lot of jitter on pin 11.
> 
> If anyone who has found a cure for this issue I'd appreciate hearing from
> you. It appears to be heat related, as the crystals age the board becomes
> very heat sensitive, and the board is in encased in what is basically an
> oven which adds to the problem.
> 
> Pete
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