11-11-2015, 10:57 PM
(11-11-2015, 05:23 PM)Nowhere-Man Wrote: ... From what I gather from my very old sets, the Grid Bias battery would be connected + to chassis and - to grid. Its purpose, of course, is to stop the grid becoming too positive.
This has already been covered further back in this thread ...
(11-11-2015, 05:23 PM)Nowhere-Man Wrote: One thing that had me thinking was also there was a need to use a grid leak as well. And now it starts to get a bit more involved.
The grid bias battery (or other supply) will be a short circuit to audio or RF signals appearing at the grid so the resistor is needed to feed the negative grid bias to the grid whilst maintaining a reasonable isolation between the signal and the bias supply.
(11-11-2015, 05:23 PM)Nowhere-Man Wrote: So, now you can add another resistor - the Grid Leak. In the very early sets this would go between the grid and the + filament. It seems any correct positive connection will do the job at the correct voltage to allow electrons to escape from the grid if it becomes too negative. So, in a way, it's a bit like another bias on an established bias - all to make sure the grid doesn't go out of wack
I've re-read this several times and still can't get my head round it!
Are you seriously proposing two grid leak resistors? There will only ever be one, returned to the bias supply or, if there is no separate bias supply as in, say, a one-valve TRF, to the earth rail.
