> The Henry has full-wave bridge rectifier then uses an 8 Henry (700ma)
> filter choke with an oil filled .1mf (7500v) in parallel then an oil
> filled 20mf (5000v) cap to ground.
> I've been told those oil filled caps rarely go bad and usually last
> longer than we do. Any clues where I should be looking to solve this
> hum problem? Of course it's not really noticeable on SSB but I'm sure
> it's in there as well.
The 8 Henry filter choke with an oil filled .1mFd in parallel then an oil
filled 20mFd cap to
ground is a tuned filter, tuned to 120 Hz. If you truly have 60 Hz hum, you
have a diode open in
one of the arms of the bridge rectifier. If you truly have 120 Hz hum, you
have a "detuned
filter" possibly the oil filled 20mFd cap has changed value. Check the values
of both caps first.
With this, like all power supplies the HUM sounds greater with a higher
current draw, from the
supply.
--
Ron KA4INM - He who attacks the fundamentals of the American broadcasting
industry
attacks democracy itself. -- William S. Paley,
chairman of CBS
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