[Amps] Strange power supply

[R at contesting.com]

The easy way to measure filter-C is to measure the time it takes for 
them to discharge through the bleeder / equalizer resistance to 37% of 
V-max.  The formula is C = T/R.

On Apr 19, 2006, at 6:07 PM, Will Matney wrote:

> Barrie,
>
> Your clue is the hum. Check all the filter caps for the HV supply. My 
> guess is that's the problem.
>
> Best,
>
> Will
>
> *********** REPLY SEPARATOR  ***********
>
> 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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>
>
>
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Rich Measures, 805.386.3734, AG6K, www.somis.org