On Aug 7, 2005, at 8:47 PM, Michael Tope wrote:
>
> ----- Original Message ----- From: "R.Measures" <r@somis.org>
>
>>> Rich,
>>>
>>> You are making an apples to oranges comparison. The issue isn't the
>>> current carrying capability of the 8877 grid, it is the power
>>> dissipation
>>> of the grid.
>> The grid has ESR. Current through R causes dissipation.
>
> Yes, of course, Rich, but the ESR is not what is entirely responsible
> for grid dissipipation due to grid current flowing
> under conditions of excessive drive. If it were, the grid
> drive voltage term would not appear in the calculation of
> grid dissipation.
>>> A capacitor has a power factor of ~0.0.
>
>> Au has c. 60% of the conductance of Cu or Ag. Just because the grid
>> has C does that mean there is no P dissipation in the grid?
>
> No, of course not, Rich, but showing that a thin piece of gold plated
> wire
It's not thin wire, it's rectangular bar stock and there are 108
segments - each of which appear to have the surface area of approx.
#16-AWG wire. .
> can carry 40 amps of RF current doesn't say anything about how much
> power it can dissipate. The anode structure of a tube has ESR too, but
> we don't calculate plate dissipation based on
> I^2*ESR. We calculate plate dissipation based on Ep x Ip - Pout.
> Changing the ESR of either structure won't necessarily change their
> dissipation significantly (e.g. if I could make the ESR of the grid
> or anode conductor zero, they would still dissipate power and get
> hot due to the kinetic energy of the electrons hitting them).
For the anode, the velocity of electrons is great, but for the grid it
seems not.
> 73 de Mike, W4EF..................................................
>
>
>
>
>
>>> ...
>> Richard L. Measures, AG6K, 805.386.3734. www.somis.org
>> _______________________________________________
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>> Amps@contesting.com
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>>
>
>
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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