One item that could mess up these observations
is the presence of significant equivalent series
resistance in the capacitors. Then the pulses
of current through the capacitors will result in
spikes of voltage across the capacitor. The
amplitude of those spikes will be dependent on
the value of that ESR. They will normally be quite
narrow as viewed on the scope. In practice the
presence of such spikes is an abnormal situation.
- JimT W4ENE
## funny u mentioned that. on PSUD, I added a RC
filter.. right after the main filter cap. The 50 ohm
R is the glitch resistor. The 'C' is the bypass cap at the
base of the plate choke. If any value of bypass cap from
.217 uf.. and less is used.... these horrible, RANDOM spikes
are everywhere, with huge P-P . Even when the ESR of the
bypass cap is down to .002 ohm, same deal, horrible spikes.
With bypass cap values > .218uf.... all is well, no spikes.
Now, if the glitch R is lowered in value, <35 ohms.. the
spikes are back with a vengeance.
With the glitch R reduced, down to just 5 ohms... the bypass
cap has to be increased to 2 uf.... or greater.
Now, normal bypass caps are .0005 to .01uf.
Is this for real... or an anomaly of psud ? To see this
effect, you have to be on the OUTPUT side of the glitch R... and
from there.. all the way to base of plate choke. Amp has to be
driven with full cxr.
later... Jim VE7RF
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