[Amps] Grid fuses (was: Life and gain of 3-500Z)

[R L Measures]

On Jul 20, 2006, at 9:10 AM, Bill Turner wrote:

> ORIGINAL MESSAGE:
>
> On Thu, 20 Jul 2006 07:16:18 -0700, you wrote:
>
>
>> If the tube is not gassy, and the grid is floating, the electron
>> stream from the cathode probably raises the grid-cathode (fil-CT)
>> potential to a few volts negative.
>
> ------------ REPLY SEPARATOR ------------
>
> I have observed this phenomenon in small receiving tubes with the grid
> floating. No doubt it applies to their big brothers as well.
>
> My understanding is the grid accumulates electrons from either the
> space charge surrounding the cathode or the cathode-anode electron
> stream and has no way of getting rid of them. Thus the grid becomes
> negatively charged to a small extent. This negative charge repels
> additional electrons from accumulating and a balance is achieved.
>
> Willing to stand corrected if necessary.
>

You got it right, Bill.
> Bill, W6WRT
>

R L MEASURES, AG6K. 805-386-3734
r at somis.org