[Amps] Dual tetrode in grounded grid

[Gary Schafer]

The other problem with it is you can't run the plates in push pull and drive
the common cathode as it will cancel the output. You would need to run the
plates in parallel but then there is the problem of the beam forming plates
as others have mentioned.

73
Gary  K4FMX

> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of Glen Zook
> Sent: Wednesday, February 11, 2009 3:26 PM
> To: Amps at contesting.com; Bill Fuqua
> Subject: Re: [Amps] Dual tetrode in grounded grid
> 
> I had forgotten about the beam forming plates!  Just like the 1625 versus
> the 837 although some brands of the 1625 had the beam forming plates
> connected outside of the glass envelope and therefore can be removed from
> the cathode and connected to another pin.
> 
> Glen, K9STH
> 
> Website:  http://k9sth.com
> 
> 
> --- On Wed, 2/11/09, Bill Fuqua <wlfuqu00 at uky.edu> wrote:
> 
> The problem is that the beam forming plates are connected to the cathode.
> That by-passes the shielding between the plate and cathode done by the
> grids. You may have instability.  In the case of some others such as some
> 1625's  you can separate the beam forming plates from the cathode by
> simply removing the base or drilling a hole in it and unsolder the lead
> from the pin and moving it to another pin.  You can't with this tube.
> 
> 
> 
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