[Amps] Dual tetrode in grounded grid

[Glen Zook]

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.