I got a blessing from the e-mails gods! My message to the reflector bounced
for some reason so I get to edit it and re-send it again! COOL!
OK:
on 3/9/00 9:31 AM, Wt8r@aol.com at Wt8r@aol.com wrote:
> If you will read again my original post which you quoted above, please notice
> that I did NOT say anything about a specific mechanism initiating the
> destruction and emphatically said (however it is initiated). Please don't
> bait and switch the discussion.
Wait a minute. Dave, you say not to use bait and switch tactics. This
whole discussion (and subject line to prove it) was on how much energy a
typical resistor in a parasitic suppressor network can withstand. Now YOU
switched it to talking about bandswitch destruction. Totally different thing
entirely! So who is doing the bait and switch routine here? In fact I fell
for it the first time I typed this message as the bottom part of my response
was about resistors and not bandswitches. Shame on me for not reading
carefully enough. Shame on you for baiting and switching.
My whole discussion about power handling came as a result of what Rich
Measures said about resistors being damaged by VHF energy due to a very,
very short parasitic event. I never said anything about power supplies, DC
arcs or whatever in my postings. Sure you can generate enough energy with a
power supply to destroy a resistor or bandswitch. No kidding! I've blown
up plate chokes too!
One fellow went so far as to say that in order to see a resistor explode,
that I should connect one to my HV supply and touch it to ground. Well, it
is quite obvious that due to the fact that the supply is hooked to the AC
mains, there is plenty of energy available to be delivered to the device.
However, if one were to take that supply and turn the AC off and discharge
the capacitors in the supply via the resistors to ground, you would NOT burn
up the resistors.
You complained that if people just read your postings, you would see that
you've never mentioned resistors but only bandswitches. I fell for it.
However, you should have replied to the original topic of discussion and
that was the question of whether or not the amount of VHF energy developed
in a parasitic oscillation would be enough to burn up the resistors in a
parasitic suppression network from the inside out.
>
> 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.
>
> 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.
>
> After using 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).
No doubt it was your power supply. I've never doubted that a high voltage
power supply could destroy something. You are correct. My contention is
that it took much more energy than what was just in the capacitor banks of
the supply.
You already stated your supply had a voltage of 4000 Volts and capacitance
of 32 uF. We've already calculated how many joules that is (something like
256 J or on that order). If the power supply was being fed from the AC mains
when the event happened there is a whole hell of a lot more energy available
than what is just in the capacitor banks.
Additionally, if RF voltages were present the time as well, we have an
additional voltage level that could be much higher than that of the DC.
Since you've given no numbers other than your power supply voltage and
capacitance and no mathematics to discuss what happened, it's impossible to
further speculate what happened or what other factors were involved. Unless
the voltage rating of the bandswitch was exceeded (and it couldn't have been
since you were using it at 4000 volts), there is no way that the bandswitch
could have been damaged from the stored energy in the capacitor banks alone.
Capacitors discharge at an exponential rate and cannot deliver an
instantaenous spike. Plus you likely had bleeder resistors on the caps
which would eat up the energy further. My numbers in previous posts were
based on that alone. But with the energy of your local nuclear or coal fed
power plant behind you, sure you could vaproize the bandswitch.
My only point in all this is that 320 Joules of energy did not destroy a
resistor (from my tests). If you want to mathematically debate me and prove
me wrong, fine. I'll take that. But then show me how a specific amount of
energy applied in one instance will destroy a part, but yet applied in
another instance, it will not destory it. Show me how I am wrong. Don't
just say I am wrong and off my rocker.
73,
Jon
KE9NA
-------------------------------------
Jon Ogden
KE9NA
Member: ARRL, AMSAT, DXCC, NRA
http://www.qsl.net/ke9na
"A life lived in fear is a life half lived."
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