----- Original Message -----
From: Tom Rauch <w8ji@contesting.com>
> One way you can weed things out is to look at the maximum limits
> of voltages or currents, and see what the maximum potential
> effects would be.
>
> > I agree Ian .... So wouldn't that lead one to think maybe a VHF/UHF
> > oscillation might have taken place ? An oscillation of some magnitude
some
> > say can't happen ???
>
> Thoriated tungsten has a maximum emission efficiency of
> approximately 100mA per watt, according to tube design data in
> Giacoletto's Electronic Designers Handbook.
>
> If your 3-500Z was operating at six volts and 17 amperes (over the
> ratings) the filament power would be 102 watts. That would be a
> maximum available emission of 10.2 amperes for an ideal filament
> structure with maximum emission.
Tom,
I understand where you are coming from here. But the fact remains it
happened not only once but twice ... just as I stated. I like to keep an
open mind ... I will listen to all for their suggestions ... I am very
curious as to what took out the tubes. Just by moving the top cover up
slightly at one end sure seems like changing a resonance inside the RF tank
circuit was possible.
>
> Let's just pretend all the available cathode current flows to the grid.
>
> Maybe someone can explain to me how a current well under ten
> amperes can shatter a grid in a twinkle of an eye, when a
> conductor with a flux .02 Maxwells per meter acting on the field of
> a 7 cm long conductor carrying ten amperes of current only
> produces 14.28 grams of torque distributed over the entire surface
> area of the conductor when the fields are aligned for maximum
> force.
Maybe something else is going on here than just DC current ????
Extreme high RF current ??? I don't know ... just thinking of possibilities.
>
> As an experiment, lay two conductors on your desk and apply ten
> amperes to each one and watch how much they move from the
> force.
>
> I have a question.
>
> Why was the cover off and the interlocks defeated on an amplifier
> that was working perfectly?
I have been trying to remember the exact reason for doing this because I
knew someone would ask ... maybe it was to measure the HV with an external
meter or maybe to calibrate the grid current meter, I honestly don't
remember.
Terry W6RU
>
>
> 73, Tom W8JI
> w8ji@contesting.com
>
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