idle curiosity
what does a 120cps hum sound like? is that G sharp over middle C ??? <G>
chas k5dam
Ron Youvan 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.
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chasm@texas.net k5dam Houston, TX
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