>
>Hi Dave,
>
>> Using the SCIENTIFIC METHOD I learned in CollegePhysics, I OBSERVED the
>> metal fragments and powder residue of the bandswitch which resulted from
>> the BIG, LOUD, LIGHT EMITTING BANG.
>
>We can determine if it was a VHF signal by measuring the
>impedances in the tank. I've NEVER found a tank that had
>impedance capable of passing VHF energy, unless they were VHF
>tanks or something built on plywood with six inch ground leads.
Sure you have, Tom. You are the guy who discovered that Tune-caps have
VHF resonances which permits VHF energy to appear on the bandswitch.
Now you are trying to ignore this important discovery because it torpedos
your case.
>
>If a conventional tank circuit suppresses VHF harmonics any
>reasonable amount at all, it won't pass enough energy to allow a
>VHF arc across the switch. One doesn't have to be highly
>educated or experienced to understand such a simple system.
Indeed. The photo of the crispy-crittered bandswitch on page 33 of the
October, 1990 *QST* demonstrates what's what.. .
At the Tune-C's resonant frequency, it looks as a low Z. However, just
above and just below the resonance it's a whole nuther ballgame.
>
>> After doing so, I concluded that the source of the energy which caused the
>> vaporization was EITHER my 5KW power supply OR a bolt of lightning from
>> outer space.
>
>That's right. Either is a logical source.
>
I'll drink to that!
>To develop enough voltage across bandswitch contacts that
>connect from one end of the tank coil to the other to cause them to
>fail, there must be a reasonably high impedance at the frequency
>causing the problem.between those points and a reasonably high
>impedance to ground at the tank input at that frequency.
>
agreed
>That condition is met ONLY at or near the operating frequency.
>
At resonance, it looks like a short. As we move off resonance, things
change.
>Of course lightning can cause the problem also, since it has so
>much energy that even a small sample of the broad energy
>spectrum can cause damage.
>
zzzzzz
>My point is only that a sudden burst of a millisecond or so of
>energy, or a VHF signal, does not fit the results.
>
Who measured a millisecond?
>> After employing the Scientific Method once again, I observed that my roof
>> was still intact, so I reasoned that the energy OBVIOUSLY MUST have come
>> from MY power supply (or maybe a photon event).
>
>Since we both know (if you have the background you imply) a
>photon event does not have enough energy to do anything to the
>tube, we can rule out that nonsense.
One photon colliding with one atom knocks down the first domino.
>
>We are left with either an oscillation or actual RF excitation at the
>resonant frequency of the tank as the source of the voltage that
>caused the arc.
>
The tank is a low pass filter.
>Of course the energy can come from the supply, and at the
>resonant frequency of the tank it doesn't need to be a large amount
>of energy. It simply has to have enough voltage to start and arc,
>and enough current to sustain the arc until the contacts are
>melted. As little as 10 watts of power can totally destroy a small
>bandswitch contact while it is arcing, because a small contact isn't
>even capable of dissipating as much energy as a two watt resistor.
>
>None of this stuff is all that difficult to understand, it is easy to
>develop several times the dc anode voltage in a high-Q tank circuit
>if the load is removed and the tube is pulling on the tank and
>supply at the same frequency where the tank is resonant.
Tom keeps repeating this Bunyanesque story even though he knows about the
max. detune test on a SB-220's tank during the grate parasitics debate.
Instead of "several times" (3kV x 4 = 12kV) , the measured potential
during mistune was 3600 peak volts.
>
>High-vacuum gas arcs or whiskers inside the tube aren't hard to
>understand either.
Whisker arcs in vacuum caps make a small tink sound.
>
>The only thing that makes this stuff difficult is trying to fit parasitics
>into every failure, and trying to fit one cure into every stability issue.
This red herring is your invention, Tom. Parasites are just one source
of failure.
>That is where the very poor science comes in, and where the fights
>start.
>
First he laments ''Poor Science''. Now he plays the ''Very Poor
Science'' card. What next -- the Extremely Very Poor Science card?.
>In those discussions, the group always splits into two camps. One
>camp says "here are the rules the circuits must follow, it can't
>happen that way" and the other camp says "we can't explain how it
>breaks the rules, but we see the results".
>
>Well, it doesn't have to break ANY of the rules and the failures
>described can happen, they just generally can't happen the "VHF
>parasitic way". Failures certainly can't be induced because of
>photons, that would be laughable if it wasn't such a sad
>demonstration of how little people know about the world we live in.
>
The laughable part is all that you have had to stonewall. Ignoring your
important discovery has gotta the cake, Tom. Second place goes to your
delightsome post of November 28.
Cheers.
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
--
FAQ on WWW: http://www.contesting.com/ampsfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|