.......
>>>First of all I have no particular disagreement with the use of a
>>>somewhat lossy material in the suppressor.
>>
>>At least, not since N7WS published his vhf suppressor measurements.
>
>Actually I never heard of his measurements until you showed up on the
>reflector. My use predates yours by probably 30 years.
>BTW, how come Wes disavows all of your claims in his name????
>
. Wes Stewart, N7WS was a supporter of Mr. Tom Rauch during the grate
VHF parasitics debate which began c. Oct of 1996. Tom's position was
basically that a VHF suppressor could be built out of copper-wire that
would equal the performance of a VHF suppressor made from
resistance-wire. What Messrs. Rauch and Stewart apparently did not
realize is that, even though such a thing is possible by adding more
inductance to Ls, and by adding more resistance to Rs, the trade-off is
that a higher dissipation capability resistor is required for Rs -- but
without increasing the inductance of Rs. (note: I found a resistor
manufacturer who could make such resistors, however, the price was around
$10,000 for a minimum order of 1000 units.)
. Wes had access at work to a Hewlett-Packard Model 4191A RF Impedance
Analyzer. During the course of the debate, Wes offered to measure the VHF
performance of similar Ls/Rs suppressors of each type. Tom sent him a
suppressor from an AL-80B(?), and I sent Wes the materials and
instructions for making one of our resistance-wire Low VHF-Q suppressors,
and he constructed one. . . Meanwhile, on the 28th of November, Mr.
Rauch proposed that he and I calculate the performance of a
resistance-wire suppressor whose Ls had a VHF-ESR of 5-ohms, compared
to that of a heavy ga. copper-wire Ls which had virtually zero ohms of
ESR. This sounded like a fair proposal to me, however, when I got around
to doing the proposed calculations a few days later, Tom's 11/28/96 post
had mysteriously disappeared from the Newsgroup. Fortunately Will,
KN6DV, had already archived the posts from 11/28/96, so I was thankfully
able to retrieve a copy. I performed the calculations. Eureka, the
mystery was solved: 5-ohms of VHF-ESR looks small, however, it has a
large effect on the performance of a VHF suppressor. . F.E. Handy was
right: "The combination of both resistance and inductance is very
effective in limiting parasitic oscillations to a negligible value of
current." {p.72, 1926 Radio Amateur's Handbook).
. Tom Rauch would neither discuss the calculations nor acknowledge that
he had proposed doing such calculations.
. My guess is that when Wes finished making the VHF measurements, he was
so certain that he and Tom were right, he published the measurements
without contemplating the actual numbers. When I pointed out that
according to Wes' measurements, the copper-wire suppressor exhibited 60%
more (undesirable) VHF-Rp than the resistance-wire suppressor, he got
steamed. . Tom continued to stonewall. . When I subsequently quoted
Wes' VHF-Rp measurements on my Website, he threatened me with a lawsuit
based on violation of U.S. Copyright Law if I did not remove the quote.
However, this law provides for Fair-Use Quotes of copyrighted material
provided that credit is given. .
. Several times, I asked Wes and Tom to design a copper-wire suppressor
that would have as low a VHF-Rp as the resistance-wire suppressor Wes
measured, however, they would have no part of it, no doubt realizing that
yours truly would surely counter by posting the calculation for the
bad-news dissipation in Rs. (calculations later posted here) . Wes got
steamier and steamier, eventually suggesting that the girl who assembles
and mails our retrofit kits was licking more than envelopes.
Eventually, Tom suggested this on the [AMPS] reflector mailing-list.
>.......
... ... "But those things which proceed out of the mouth come forth from
the heart and they defile the man".
cheers
Rich...
R. L. Measures, 805-386-3734, AG6K
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