11-09-2021, 09:11 AM
(This post was last modified: 11-09-2021, 09:11 AM by Murphyv310.)
If we look at the "D" series valves and how they behave in a battery radio, we see that a fresh LT battery giving often more than 1.5v gives the set a boost, as it reduces to 1.1v performance takes a noticable drop.
The Rod Pentodes though often go the other way, with a reduction increasing gain. At the moment the project filament volts are 0.93v and its performance is the best so far. One day I was fiddling with a 1j42a and unknowing to me the battery had dramatically dropped to 0.6v and with only 3v on the anode it was quite amazing on gain, not as high as the sweet spot but working well, a small increase or drop in filament volts and gain went well down, perhaps there is two sweet spots.
The Rod Pentodes though often go the other way, with a reduction increasing gain. At the moment the project filament volts are 0.93v and its performance is the best so far. One day I was fiddling with a 1j42a and unknowing to me the battery had dramatically dropped to 0.6v and with only 3v on the anode it was quite amazing on gain, not as high as the sweet spot but working well, a small increase or drop in filament volts and gain went well down, perhaps there is two sweet spots.
