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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