> From: "Tom Rauch" <w8ji@contesting.com>
>To: amps@contesting.com
>Date sent: Mon, 7 Jun 1999 07:16:30 -0400
>Subject: Re: [AMPS] TL-922 Filament Transformer Protection
>Send reply to: W8JI@contesting.com
>Priority: normal
>
>Subject: Re: [AMPS] TL-922 Filament Transformer Protection
>Date sent: Sun, 6 Jun 1999 08:29:51 -0700
>From: Rich Measures <measures@vc.net>
>To: <W8JI@contesting.com>, <amps@contesting.com>
>
>
>I wrote:
>> >The "omission of fact" that you used to distort the answer was that the
>> >particular capacitors I measured with high VHF low UHF resonances
>> >contained SERIES resonances, where the impedance went through a wide DIP
>> >in impedance.
>> >
>> ? What is the likely Z of a high-Q series-resonant circuit on
>> frequencies above and below the frequency of resonance? As I recall, you
>> measured an AL80 Tune-C series-resonance at c. 180MHz, and the parasite
>> took place c. 160MHz.
>
>I expect you to "look for" a parallel resonance in the capacitors Rich,
>and claim there must be one (without measuring properly) because without
>a crummy capacitor that has hundreds or thousands of ohms of VHF
>impedance your entire "a VHF parasitic arced the bandswitch" theory falls
>square on its nose.
? In order to develop a high potential, high current flow is essential.
Series-resonance causes high current-flow. Parallel-resonance does not.
. At the frequency of series-resonance, virtually no potential can be
developed. However, at frequencies slightly above or below
series-resonance, high potentials can be developed. This is essentially
how an L-matching network works.
>So of course you want to "invent" a parallel resonance below the series
>resonant frequency! Otherwise everyone who swallows your parasitic BS
>would see through the farce!
>
? not a sound wager.
>But common sense prevails in many people. If a capacitor had a parallel
>resonance at VHF, the amp would be TVI trash-city. It would probably
>never pass FCC tests for harmonics measured at VHF. Virtually all amps
>show a smooth rapid decrease in harmonics with increasing frequency.
>None I've ever seen have the Hi VHF Z capacitor you desperately search
>for. Without it, your VHF bandswitch fantasy can not be true.
>
>The capacitors typical to AL-80's, SB-1000's, SB-220, L4B's and so on
>have a smoothly decreasing impedance up to a minimum of almost zero ohms
>at 180 MHz. Above that the impedance slopes slowly back upwards in
>reactance with the opposite sign. The ones I measured don't look like a
>high Z at any frequency until up around 400-500 MHz or higher, and even
>then the impedance isn't all that high.
>
>Maybe you should change your song and dance to UHF or Microwave parasitics?
>
>> >You did the same thing with the measurements N7WS made on
>
>> >suppressors. It seems to be your pattern.
>>
>> ? According to Wes' measurements, there was about a 40% decrease in
>> VHF-Q with the resistance-wire suppressor compared to the copper-wire
>> suppressor. Are you suggesting that more suppressor Q equates to more
>> stability?
>
>Wes' conclusion (that HE posted) was there was no real difference
>between the suppressors.
? RE: Wes' 100MHz Q measurements: The Hewlett-Packard Model 4191A RF
Impedance Analyzer measured the Q of the copper-wire/W8JI suppressor at
2.2. The resistance-wire suppressor had a measured Q of 1.5. Thus, it
sort of looks like the copper-wire suppressor had 46% more Q at 100MHz
than the resistance-wire suppressor. Is 46% no real difference? ..
>You are the one who changed that post by
>omitting facts and misapplying data. As you typically do.
>
- Cheers, Tom
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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