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


The high voltage is a little over 900V. The medium voltage is 300V.
Those are the two lines I shorted together momentarily by accident.
That's when the receiver became highly distorted. Don't know the
effect on transmit yet, but expect similar problems. The HV line is
fused. The 300V line is not. The fuse blew instantly. I suspect the
damage, if any, is in the 300V section. The Swan supply was
completely rebuilt with an upgrade board. The only old components
remaining are the power transformer and the choke. Everything else is
new. Everything was working great until I got clumsy with a probe.

The Fluke 87 is a true RMS DVM with a max input for AC and DC of 1000
volts. I have a Tektronix 475 scope. It has a max input of DC
coupled: 250 V (DC + peak AC) or 500 V P-P AC at 1 kHz or less.
AC coupled: 500 V (DC + peak AC) or 500 V P-P AC at 1 kHz or less.

I don't know much about the use of oscilloscopes. Just enough to be
dangerous. I'm assuming I need some type of probe that will let me
test the 900V line in the supply without damaging the scope. I can
see A/C ripple on the 300V line, but I don't know how much is too
much.

Dick
** Posted from http://www.teranews.com **