Rich:
I raised the question of increasing the screen voltage on a grounded grid
tetrode - from zero to something less than the "normal" voltage. Your
response was that "DAF circuits produce feculance".
Your latest response is:
"Did I not also point out that the power out with your stated screen
potential was comparable to the power from the driver?."
Your answer does not make sense. Let us assume we have a normal grounded
grid tetrode. Now, we break the screen lead to ground and insert a 1 volt
regulated positive voltage upon the screen. Will the power output drop to
that of the driver? What about 2 volts? As the screen voltage is
increased, resting plate current will increase and at some point grid bias
will have to be applied as the plate changes color from red to white.
In a grounded grid tetrode, the control grid current will be greater than
the screen current. By raising the screen voltage above ground, control
grid current will decrease.
What sort of interesting curve do you have that shows that power output
drops to the input power as soon as the screen voltage is raised above
ground - yet will reappear as soon as the screen voltage is raised to the
rated screen voltage. That would be an inverted square, wouldn't it?
The 4-400 is rated to have 100 ma of control grid current when used in
grounded grid configuration. Are you saying that as soon as I lift the
screen above ground that any grid current will cause splatter?
Colin K7FM
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