[Hallicrafters] AC/DC Halli's, Grounds and HUM

[Phil Atchley]

Hi Rick
Almost, but no banana.  In this set the ground screw is connected to the
chassis and the chassis connected to the 'neutral' line through a capacitor.
So the chassis is only truly "hot" if the capacitor fails.  IF the power is
off the chassis is bypassed to the "hot" wire through the filament string
and capacitor.  I haven't yet got around to changing the power switch
wiring.  I don't know why all the radio companies switched the power line
lead that went to the B- side of the power supply (guaranteeing that the
chassis will buzz you either with the power on or with it off).  I did
change the wiring on all three Minervas that I did for Duane so that with
their polarized line cord the chassis is always "neutral".
73 de Phil  KO6BB


> The "ground screw on those ac/dc sets is connected through a capacitor
> to the chassis which is connected to one side of the ac line cord.
> Are you seeing a pattern here? The other side of the line cord is
> bypassed to the chassis by a capacitor! You have just formed what we
> call a ground loop, ouch. I have buzzed my finger tips many times
> when touching those terminals on my s-38b. Useing the other two
> screws with out the ground strap does not make any connection to
> the radios chassis. The ground strap is best used for single wire
> or long wire type antennas.
> rick wa8ylz



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