[Amps] 120 cycle hum from Henry 2K-4

[chas]

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.


-- 
chasm at texas.net   k5dam  Houston, TX

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