> You raise a good point which could be extrapolated like
> this: Parasitic
> oscillation MAY be the cause for SOME grid-to-filament
> shorts. There has
> been equal number of situations where the application of
> Rich's nichrome
> wire suppressors eliminated the problem as well as not.
In random tests when an unknown intermittent problem occurs,
no change at all can result in what people perceive as a
cure.
This why double blind tests are done.
The random coincidence effect is why the new age medicines
and the old copper bracelets for arthritis have a following
that will argue to the death about the wonderful cures, and
why numerology and astrology have followers.
For example if I had an amplifier with a tube that randomly
failed twice, and I changed the suppressor and the tube, I'd
have no idea at all if it was blind luck or the suppressor.
If I had a problem with an intermittent arc and I took
everything apart and cleaned it up as well as adding
nichrome, I'd have no idea if dismantling and perturbing
several things fixed the problem or the nichrome did.
What CAN be proven beyond a doubt is nichrome makes very
little difference at VHF over a simple turns or resistance
adjustment in a conventional suppressor. The VHF
performance is essentially the same. The greatest difference
is at HF and lower, not at VHF. This is easy to prove, and
100% repeatable.
N7WS made independent measurements of this.
I measured the Q of a nichrome kit for 3CX800's, and the
actual VHF Q increased with the nichrome over the stock
suppressor. That was because the nichrome was a hairpin and
not a multi-turn coil like the conventional suppressor.
73 Tom
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