Or you have a ground loop or audio issue with this setup. I see that you
have no hum with the SB200.
73
Jim W7RY
On Thu, Feb 18, 2010 at 5:07 PM, Ron Youvan <ka4inm@tampabay.rr.com> wrote:
> > 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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>
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