On Fri, 2009-07-17 at 12:53 -0400, David Drake wrote:
> Jerry,
> Thanks again for the advise. You called it. Radio back on frequency
> (compared to another radio), and hum gone. When I did the resistor change
> for a heil mic, I must not have tightened the mounting screws enough and
> when working with the interface connector, it developed a ground problem.
> 73's
> David
> Wd9cmd
>
Over the last 30 years, I expect that cure has fixed more than 25
radios, some here on my bench, my own radios, many on the air or via
internet. Fact is squeezing the ground connection with plastic looses
that pressure (the dictionary definition of "plastic" is flows under
pressure to relieve that pressure even if you hadn't loosened the
screws, but the fact that trying the RS-232 cable broke the radio was a
good clue that grounds had moved.
It was beat into me at Collins about 26 years ago that one never uses
any insulator to keep pressure on an electrical connection. Not even
the hard plastic of a Jones barrier strip. Don't ground the braid to the
mounting screw. Still proves to be right, and so I don't like power pole
connectors that depend on plastic for contact pressure.
73, Jerry, K0CQ
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