05-12-2016, 10:27 PM
Hi.
I was just thinking that a centre tapped RF transformer will feed both grids in antiphase so in effect the output will be zero at RF, so I would think a centre tapped TX isn't the way to go.
Looking at the data of the valve you can see that the GM of the valve is highest with both control grids connected in parallel which makes sense but it's lower than halved when used singly.
What I did find today is the grid used for audio input, linearity could be improved by biassing it at about 0.5v negative with respect to the filament minus connection. I was able to gain a little more modulation before distortion, also running the "HT" at 6v reduced the distortion too. The original circuit is a basic building block, I'm sure I can improve on it with time.
I was just thinking that a centre tapped RF transformer will feed both grids in antiphase so in effect the output will be zero at RF, so I would think a centre tapped TX isn't the way to go.
Looking at the data of the valve you can see that the GM of the valve is highest with both control grids connected in parallel which makes sense but it's lower than halved when used singly.
What I did find today is the grid used for audio input, linearity could be improved by biassing it at about 0.5v negative with respect to the filament minus connection. I was able to gain a little more modulation before distortion, also running the "HT" at 6v reduced the distortion too. The original circuit is a basic building block, I'm sure I can improve on it with time.
