On Aug 7, 2005, at 9:16 PM, Michael Tope wrote:
>
> ----- Original Message ----- From: "R.Measures" <r@somis.org>
>
>>>
>>>> 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. .
>>
>
> Well....yes..... but the argument is still the same. And if grid
> dissipation
> were a function simply of conductor ESR, why would even 350mA let
> alone 100mA be a big deal for a #16 AWG equivalent conductor? A
> #16 AWG conductor could carry 350mA all day long even in a vacuum.
As I recall, Eimac says grid dissipation in watts is approximately
equal to DC grid-I multiplied by rms grid to cathode potential.
Apparently, electrons that strike the grid are not going all that fast.
>
>>> 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.
>
> In either case its a function of the accelerating voltage. For the
> anode
> its a function of Ep x Ip, for the grid it is a function of Eg x Ig.
Agreed, +/– 5%.
cheers, Mike
>
> 73 Mike, W4EF........................
>
>
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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