[Amps] Strange power supply

Will Matney craxd1 at verizon.net
Wed Apr 19 21:07:09 EDT 2006


Your clue is the hum. Check all the filter caps for the HV supply. My guess is that's the problem.



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On 4/19/06 at 6:52 PM Barrie Smith wrote:

>I recently boxed-in my all-purpose power supply with thin panels of wood,
>in order to protect the cats, and run my 432 amp.
>Just prior to the box-in, I ran my 8877 6M amp at 4200 volts idle, and
>3800 volts at 1 amp load with no problems.
>Now, attached to my 432 amp (2 X 3CPX800), running 3000 volts idle,
>results in 2000 volts under 1 amp load.
>I've run this amp on the same power supply in the past with no problems,
>although it's been awhile.
>I've taken the panels off, thinking that I've screwed something up, but
>the results are the same.
>Under a 1 amp load I'm also hearing a (60 cycle?) loud hum, that increases
>in volume as the loading is increased.  I've never heard the hum in the
>past, even when running the 6M 8877 amp at above ratings.
>This is not a whimpy power supply.  It has a 2 amp, 5000 volt Peter Dahl
>transformer, with a 30 amp variac.
>Before I start throwing parts all over the room, does anyone have a clue
>as to what I may have going on here?
>73, Barrie, W7ALW
>I've cleaned the step-start relays, which are each 25 amp, and put contact
>cleaner on the variac.
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>Amps at contesting.com

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