On Aug 26, 2006, at 5:31 PM, Tom W8JI wrote:
>> 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.
At 50MHz, on a Boonton Q-meter, the Q a Cu wire inductor is about
5.5X that of a similar Ni-Cr wire inductor.
>
> N7WS made independent measurements of this.
N7WS, Wes, was the man who single handedly ended the grate parasitics
debate between Tom and me by measuring the Q and parallel-equivalent
R (Rp) of a conventional parasitic suppressor and that of a low VHF-Q
parasitic suppressor -- And publishing the results without first
consulting with Tom. The results:
http://www.somis.org/Rp-comp.html
>
> I measured the Q of a nichrome kit for 3CX800's, and the
> actual VHF Q increased with the nichrome over the stock
> suppressor.
What was the Q of the low VHF-Q suppressor, Mr. Rauch? thanks
> That was because the nichrome was a hairpin and
> not a multi-turn coil like the conventional suppressor.
>
> 73 Tom
>
>
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>
R L MEASURES, AG6K. 805-386-3734
r@somis.org
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