PeterD wrote:
On Wed, 09 Apr 2008 00:06:58 GMT, "James Sweet"
wrote:


"PeterD" wrote in message
...
On Tue, 08 Apr 2008 17:17:17 GMT, "James Sweet"
wrote:


"Dick" wrote in message
...
I have a high voltage power supply (Swan 117cx) that may be the cause
of high distortion in the radio it supplies power to. How would I
test for excessive ripple, etc? The voltages are correct.
** Posted from http://www.teranews.com **
Scope it under load.

With a suitable highvoltage probe.
Well that's a given.

I'd never assume that! g

He didn't specify how high the "high voltage" is, if

He said a Swan which is probably an old(er) tube HF rig. I'd guess as
much as a kvolt on the finals.

it's only a few hundred volts, a normal 10x probe should be fine. Up to a
couple thousand, a simple resistor divider will work ok.

Yes, I though about a resistor divider too. I hope the OP doesn't kill
himself!

Sometimes there's a bleeder resistor on the output of the supply.
Often, it's made up of several series resistors.
Sometimes you can measure the ripple across the bottom resistor and
do the math. Or just install another resistor in the bottom
of the bleeder chain.

Or just unhook the cap, drive it with a pulse generator and look at it on
the scope. The shape of the waveform will tell you the capacitance
and ESR of the cap. If the cap is good and the diodes are good, there
ain't much else to look for.
mike

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