I found exactly the same, Steve. The (brown-ish) foam packing had
disintegrated so badly that I could neither remove it in one chunk, nor
could I put it back. I suspect its caused by age rather than by RF. From
my time in the chemical industry I know that people routinely "extend"
foam with fillers - to reduce the cost. Foam "rubber" underlay for
carpet is a favourite. Looks and feels great when installed, but a few
years later its gone to powder. We made more money selling scrap
(reject) resin for filling carpet underlay than we did out of the first
quality stuff.
(I suggested we stop making the good stuff, but the firm thought that
making (s)crap resin might be bad for our image)...
I guess I'm saying you should not use a chunk of carpet underlay foam
as a replacement, however good it feels right now.
The relay (IMHO) is not as noisy as the power relay in my Omni-V. I
found a sheet of flexible foamed plastics material that had been used
to protect the back of a computer motherboard, for shipping purposes.
It was about 1/8 inch thick so I hacked a piece to fit and installed it
(no glue) under the vacuum relay board. As far as I can tell, it
deadens the sound a bit, which is all I expected. The stuff I used will
probably last at least as long as the original, maybe longer because it
was made specifically for an electronic application.
73 - John
On 29-Sep-99 Steve Ellington wrote:
>
> I'm in the process of replacing the vacuum relay in my Hercules II
> and
> hope to improve the noise isolation. Here is a description of how it
> is
> mounted and any suggestions for improvement are appreciated. Removing
> the
> bottom cover of the amp we find another layer of aluminum to remove
> which,
> on it's top side, houses the vacuum relay assembly. This relay
> assembly
> consists of a small vacuum relay about the size of your little finger
> mounted on a small circuit board. The board is about 1" x 2" and has
> mounting holes in each corner. In each mounting hole is a standard,
> black
> rubber gromet with a bolt/washer through it to hold it to the
> aluminum
> base. Undert he board is some gray foam rubber. The foam seemed to
> have
> been glued to the aluminum and was in very poor condition.......
>
> Steve Ellington N4LQ
> N4LQ@IGLOU.COM
>
>
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E-Mail: John - G3JAG <patents@dx0man.prestel.co.uk>
To: <tentec@contesting.com>
Date: 29-Sep-99
Time: 18:13:00
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