[Amps] 120 Hz hum from Henry...

[Roy]

"Be careful if you fix this. It's not tuned to *exactly* 120 Hz because that 
would cause a
very high voltage to appear across the choke. Use the specified values if 
you replace
anything."


I strongly believe the above is a perpetuated old hams' tale, totally 
untrue. The parallel-tuned circuit is a frequency-rejection filter, 
exhibiting a very high Z to the 120 Hz ripple, thus preventing high 
circulating current and its resultant voltage build up. Read the article, 
noting the careful tuning to exactly the 120 Hz resonant frequency: 
http://www.qsl.net/i0jx/supply.html

73,   Roy    K6XK