[Amps] Fw: "Tubes 201" - How Vacuum Tubes Really Work

[Peter Voelpel]

Will,

the RF drive in GG is developed directly at the cathode.
The cathode choke forms a RF resistor in parallel to the tubes input
impedance from cathode to ground.
The positive going cycle develops a positive voltage to ground, the negative
cycle a negative voltage across that resistance to ground.
Therefore during the negative cycle the grid becomes positive with respect
to the cathode and large grid current is drawn.

73
Peter


-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Will Matney

I should have added; On that, I agree it's the only way to make one positive
(for only part of a cycle on a grid driven biased grid). A grounded grid,
cathode driven, cathode at ground potential tube though, I can't see the
grid being positive. Here, the electrons flowing through the tube is varied
by the signal, and those same electrons are what travels to the grid to
charge it. In this case, the grid is being bombarded by electrons. If the
grid was less negative, it world attract electrons until a balance was
reached then repel them. The voltage on the grid could never raise above 0
Vdc as I see it.

Best,

Will


*********** REPLY SEPARATOR  ***********

On 7/25/06 at 2:15 PM Will Matney wrote:

>Peter,
>
>On that, I agree it's the only way to make one positive (for only part of
>a cycle). Are there any other ways to make the grid positive and the grid
>be at ground potential with the cathode at ground? A lot of amps cathodes
>are at ground potential unless biased.
>
>Best,
>
>Will
>
>
>
>*********** REPLY SEPARATOR  ***********
>
>On 7/25/06 at 8:04 PM Peter Voelpel wrote:
>
>>Nothing is easier then that if the cathode is going/driven negative with
>>respect to ground.
>>Grid voltage is always measured from grid to cathode, not to ground.
>>
>>73
>>Peter
>> 
>>
>>-----Original Message-----
>>From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
>>Behalf Of Will Matney
>>
>>please explain how a grid becomes positive when tied to ground?
>>
>>
>>
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>
>
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