on 3/8/00 12:04, measures at 2@vc.net wrote:
>> If you can take time out of insulting Jon for a moment, I have a
>> question.
>
> Jon insulted himself by ignoring the most potentially destructive source.
Sorry. I did not. We are back to my original point at long last.
Rich's claim is that the most destructive source that will wipe out
components in the tank circuit is a VHF parasitic oscillation.
That oscillation is generated in the amplifier circuit, where the tube is
the active element. As such, it is affected by things such as the gain of
the tube, feedback, values of the L and R in the suppressors, etc.
As W8JI points out, one of the greatest limits to the level of the power of
the VHF oscillation is the emissivity (did I spell that right) of the tube.
I would agree with Tom on this. There is only so much that the tube can
supply in a finite amount of time.
Rich also claims that this event is so quick that it cannot be measured.
The meters on the front panel of the amp will not show it. Perhaps it could
be measured on an O-scope but I don't think that's been done.
Now we also know from my testing that the MOX resistors Rich supplies can
handle at least 320 Joules of energy without being damaged.
A parasitic event lasting 0.5 milliseconds in duration with an energy level
of 320 Joules would require 640 Kilowatts of power. I submit that in order
for resistor damage to occur, the event would need to be significantly
longer since no tube that I know of in amateur service could generate an
instantaneous peak level of 640 Kilowatts.
So I don't think I've ignored the most powerful force as Rich says I have.
Perhaps I need to do an experiment with Carbon film resistors since Rich has
never said that he's seen parasitic damage done to his MOX resistors. So if
we no the amount of Joules required to destroy a carbon film resistor, we
should be able to work backward and see how many watts we'd need in a short
time.
73,
Jon
KE9NA
--------------------------------------------------------------------------
The Second Amendment is NOT about duck hunting!
Jon Ogden
jono@enteract.com
www.qsl.net/ke9na
"A life lived in fear is a life half lived."
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