Andrew....
It's important that you accurately identify and characterize your PTO's
behavior, to have a hope of correcting it. The approaches to "drift" and
"jump" in frequency are completely different, and you will spend hours
chasing geese in the wrong direction.
Abrupt frequency changes are almost always mechanically induced. Broken
solder joints, dirty contacts or connections, loose mounting screws and the
like come to mind.
Long, slow changes in frequency are almost always caused by thermal effects
on frequency-determining components. Designers do their best to balance
these effects when the circuit is designed, but if they had ever succeeded,
we probably wouldn't have to worry about phase noise today. ALL free
running oscillators drift to one extent or another.
The other day, a list member offered you one of my Stabilizers at a very
good price. My advice would be to get that from him, and I will be happy to
provide whatever assistance you require in installation AFTER you repair
whatever mechanical problem you have.
Phil C. Sr.
k4dpk
----- Original Message -----
From: "Andrew Moore" <andrew.nv1b@gmail.com>
To: "Bwana Bob" <wb2vuf@verizon.net>; "Discussion of Ten-Tec Equipment"
<tentec@contesting.com>
Sent: Tuesday, September 06, 2011 9:43 PM
Subject: Re: [TenTec] Solving PTO drift
> Bob, you are correct - I should clarify this is more of a jump than a
> steady
> drift. It wavers slowly, both plus and minus around the desired
> frequency.
> A fan blowing ambient air into the holes in the chassis near the PTO
> seemed
> to help stabilize it tonight on a 1.5-hour sched, but that would indicate
> a
> temperature problem, not (necessarily) a mechanical PTO one. I did
> rebuild
> the PTO nine months ago, with a Ten-Tec rebuild kit on hand, but to be
> perfectly honest I can't remember if I used the kit or if I just cleaned
> the
> parts! In any case, it's also possible the lithium grease that I used
> isn't
> favored by the PTO. From what I understand, lithium grease hardens up a
> little bit after the initial application.
>
> More experimenting in order - thanks for your help.
>
> --Andrew, NV1B
> ..
>
>
> On Tue, Sep 6, 2011 at 9:10 PM, Bwana Bob <wb2vuf@verizon.net> wrote:
>
>> Andrew:
>>
>> That sounds more like frequency jumps, not drift. In that case I would
>> look
>> for a cold solder joint or get a PTO rebuild kit from Ten Tec.
>>
>>
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