[Amps] FW: 4 x GU-81 Grounded Grid Penthodes

[Fuqua, Bill L]

I must really be sleepy, I should have said that secondary electrons have very low kinetic energy.
Does not take much field to repel them, so a massive supressor grid is not necessary.
73
Bill wa4lav
________________________________________
From: amps-bounces at contesting.com [amps-bounces at contesting.com] On Behalf Of Fuqua, Bill L [wlfuqu00 at uky.edu]
Sent: Tuesday, February 28, 2012 9:52 PM
To: Carl; Roger (K8RI); amps at contesting.com
Subject: Re: [Amps] 4 x  GU-81 Grounded Grid Penthodes

Suppressor grids have very few wires per inch compared to the control grid or even the
screen grid. The primary electrons from the cathode should be not be affected enough
to be an issue. Secondary electrons have very low potential energy and are easy to
deflect.  The problem with secondary electrons occurres when the screen grid is
more positive than the plate and are drawn from the plate to the screen grid.
 That is where the dynatron region exist.
73
Bill wa4lav
________________________________________
From: amps-bounces at contesting.com [amps-bounces at contesting.com] On Behalf Of Carl [km1h at jeremy.mv.com]
Sent: Tuesday, February 28, 2012 8:58 PM
To: Roger (K8RI); amps at contesting.com
Subject: Re: [Amps] 4 x  GU-81 Grounded Grid Penthodes

----- Original Message -----
From: "Roger (K8RI)" <k8ri at rogerhalstead.com>
To: <amps at contesting.com>
Sent: Tuesday, February 28, 2012 6:50 PM
Subject: Re: [Amps] 4 x GU-81 Grounded Grid Penthodes


On 2/28/2012 1:43 PM, Máximo EA1DDO_HK1H wrote:
> Hi all,
>
> Ok, so lets do that, 4 x GU81 grounded grid configuration.
> Anyone has a schematic to follow?
> What levels could be fine?
As  the suppressor grid is normally grounded and serves as a shield to
prevent secondary emission, how would this affect running the tube in
grounded grid...if at all?
I would think it would tend to lower the gain in GG, but that's just a
guess.

73

Roger (K8RI)


Its no different than an 803, PL-175A, etc. Add about 50V to the suppressor
to increase the gain a bit. Most dont want to bother with a LV supply.

Crl
KM1H


>
> Thank you
>
> 73, Maximo - EA1DDO
>
>
>
>
>> From: wlfuqu00 at uky.edu
>> To: ea1ddo at hotmail.com
>> Date: Mon, 27 Feb 2012 16:25:31 -0500
>> Subject: RE: [Amps] 833A/GU-48 x4 Amp support
>>
>> Maximo,
>>    Look at:
>>   2 x GU81 Grounded Grid;
>> http://f5ssk.blogspot.com/2011/06/2-gu-81-grilles-la-masse.html
>> If you ground all the grids you don't need a bias supply.
>>
>>
>> 73
>> Bill wa4lav
>> ________________________________________
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>


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