Space Potential Grid

This is continued from a previous today's post on grid at space potemtial.


The 1H4 sounded great with 1.3V heater voltage, 10V plate supply voltage and open or floating grid.


How about a 9volt battery inside a Bulgin holder (then in series with a suitable fuse for safety) supplying both heater and plate?


Suitable electron tubes deliberately underheated may be 12SK7, UF89, both triode connected or ECC82 or 2 EF183 triode connected with heaters in series. Or Nuvistor 13CW4. The control grid floating or open grid or at space potential. All of these terms should mean the same thing.


So a variation of the Pleiades V6 circuit may be:





With a 9V battery in series with fuse. No pull up or Pleiades bias resistor. Cc is usually 22nF.


A 9V battery would greatly underheat the cathodes of such electron tubes.


Variations in battery would not much affect performance. When the heater voltage is higher, the space grid bias or space electric potential becomes more negative by more energetically emmited electrons near the grid and vice versa [Atkins].


See also that the grid potemtial may increase when plate potemtial is applied:



http://euroelectron.blogspot.com/2018/08/the-grid-space-potential-increases-when.html


Reference:


Patent US2850674 - Atkins


Low Plate Potential Tubes - Atkins


Open-Grid Tubes in Low-Level Amplifiers - Robert J. Meyer - Electronics - Oct 1944