[Amps] L-4PS Transformer Buzz

[Ron Youvan]

>> however. Last night about 20 minutes after I fired up the power
>> supply I noticed a loud 60 Hz buzz coming from the supply. Pressing on
>> the sides of the cabinet or changing the physical orientation of the
>> supply didn't seem to help. When I switch to the low-voltage setting on
>> the L-7, the buzz stops. Also if I let the supply cool off the buzz
>> stops for a while and then returns after the supply warms up. Looking at
>> the supply in the dark, I saw no evidence of sparking. Additionally, the
>> amplitude of the buzz seems to be totally unaffected when I go from
>> standby to full RF output power.

>> Any ideas on what might be causing this problem?

> Could be a bad cap, one installed wrong (it will blow eventually but it will
> get real warm first), missing, miswired or bad equalizing resistor.
> The transformer is trying to tell you to stop!

   I've seen this many times when a diode shorts out, even car alternators "whine"
when one diode shorts out.
-- 
    Ron  KA4INM - He who attacks the fundamentals of the American broadcasting industry
                  attacks democracy itself.        -- William S. Paley, chairman of CBS