[Boatanchors] VFO Drift

[D C *Mac* Macdonald]

Many years ago when I lived in Harlingen, TX while
attending USAF Navigator School, local hams told of
putting National receivers in the oven at something
less than 200 degrees once a year to dry out the
phenolic coil forms that had absorbed moisture from
the ALWAYS damp air there.
 
Needless to say, plastic components that might suffer
from high heat had to be removed before that treatment.
 
I suspect that similar treatment would have done the
trick on the Galaxy VFO board.

 
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~ 73 - Mac, K2GKK/5 ~
~ (Since 30 Nov 53) ~
~ Oklahoma City, OK ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~




----------------------------------------
> Date: Fri, 9 Jul 2010 10:37:56 -0700
> From: jfor at quik.com
> To: collinsradio at comcast.net
> CC: boatanchors at qth.net
> Subject: Re: [Boatanchors] VFO Drift
>
> FWIW, the board material had likely absorbed water, changing its
> dielectric constant, hence the frequency.
>
> Best,
>
> -John
>
> =============
>
>> I thought that I would pass this on for what it is worth.
>>
>> A friend of mine was utilizing the solid-state PTO board from a WRL Galaxy
>> V,
>> Mark II for his new homebrew transceiver project.
>>
>> Tony told me today that the problem was not the components mounted on the
>> board but the board itself. When he mounted the components on a new board
>> made of plexiglass material, the drift problem went away. It seems that
>> the
>> original board was the problem since it was made of some kind of phenolic
>> material. When he even blew on the board, the frequency would begin to
>> take
>> off.
>>
>> The new PTO drifts less than 200 cycles over a period of an hours and then
>> settles down.
>>
>> Has anyone experienced a similar occurrence?
>>
>> That original material that WRL used for the PTO evidently had lost its
>> insulation properties.
>>
>> He thought sure that it was not a component failure since he had replaced
>> everything on the old board.
>>
>> Thank you
>>
>>
>> David Knepper, W3ST/W3CRA
>> Publisher of the Collins Journal
>> Secretary of the Collins Radio Association
>> www.collinsra.com
>> Join today
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