>>>experiement,
>>>derived through proper DOE (Design Of Experiement) procedures, would
>>>the
>>>interested parties ante up?
>>
>>AMEN Arlen! Count me in.
>
>I agree, Carl. I would be very interested in this. It would put to rest
>all of the "religion" that all of us experience with regard to this
>topic.
>
>However, I agree as you do that it would be difficult to consistently
>recreate an oscillatory condition w/o some work. DOEs typically need to
>be controlled experiments with the correct variables picked to do the
>proper analysis. If the wrong variables are picked, or the wrong limits
>on the variables or the experiment is not properly controlled, you can
>compile all the statistical data you want and it won't mean a thing.
>Believe me - been there; done that.
>
>So Arlen and Carl, what sort of DOE do we want to do? Keep it simple and
>do a 2x2? Or should we make it more complex.
>
>A simple 2X2 could consist of:
>
>Variable One: Oscillation - Yes or No
>Variable Two: Supressors - Rich's or Carl's
>
>Then we could create a 2 x 2 matrix with these variable.
>
>However, I would suspect that this isn't enough
My guess is that there will Never be enough evidence for some. . For
example, on 28 Nov., 1996, Mr. Rauch proposed that we calculate the
parameters of a parasitic-suppressor that used a resistance-wire Ls,
whose ESR was 5.0-ohms (semi-equiv. to a 100nH Ls made from #22-ga.
Ni-Cr-Fe wire). . . Presumably, after calculating the effect that
this resistance had on the performance of the suppressor, Mr. Rauch
quietly cancelled his post and stonewalled the matter. Meanwhile, Mr.
Stewart was making his suppressor measurements with the Hewlett-Packard
Model 4191A RF Impedance Analyzer. These measurements indicated that for
a resistance-wire Ls whose ESR is c. 2-ohms, suppressor performance
improved by about 40% at 100MHz compared to a conventional (W8JI)
copper-wire parasitic-suppressor. . In other words, even though he knew
that his theory (that it makes no difference what Ls is made from) was
flawed -- Mr. Rauch fought tooth and nail for over a year to deny what
his calculations told him and what Wes' measurements confirmed. .
> and we may have to go
>larger like a 4x4 as we haven't even taken the gas arcs into account, let
>alone any other modifications that are done to the amps.
>
>Also, you would want to do this on multiple amplifiers. How many
>repetitions are we going to have? 3? 4?
>
>I am not being funny or sarcastic here. I am totally serious.
>
>All this is needed for a successful DOE. I have texts and papers on this
>subject if anyone needs info..........
>>
>>
>>I do not think that a methodical approach will work very well...at least
>>with the SB-220. I have tried numerous times over the past few years to
>>recreate "events".
>
>Well, then a true DOE probably won't work. It's gotta be done
>methodically.
>
>I guess trying to catch parasitic events is like trying to find Big Foot
>or the Loch Ness Monster. Some people claim all sorts of stuff! :-)
Yes, like a Mumetal cures-all VHF parasitic suppressor. However, vhf
parasites have a well-earned reputation of popping up when you least
expect it.
>
>>As has been previously pointed out, there is no guarantee that the series
>>cap will work on every antenna combination. With a Bird dummy load there
>>is no problem. With the average feedline to say a tribander being 100' or
>>so the flat loss in the coax will flatten out the VSWR antenna response
>>at VHF/UHF.
>
>If the output Pi-network of the SB-220 has a low-pass response as most
>output networks do, then what difference at VHF/UHF does the antenna make
>anyhow? Do we really need some sort of a load?
Amen. The 80m Tank L in a SB-220 is 10uH. At the parasitic frequency of
110MHz, this represents 6910 ohms of reactance essentially in series with
the antenna, which is typically shunted by 1000pF or so of Load-C. .
>After, everyone talks
>about how the output Pi-Net works as a filter to remove the harmonics, so
>if it removes (or reflects - The S11 of the filter at the frequency of
>the harmonic energy is high) harmonics, won't it also reflect VHF/UHF
>energy?
yes
>Why worry about how the HF load looks at VHF/UHF?
>
What, me worry?
cheers
Rich...
R. L. Measures, 805-386-3734, AG6K
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