[R-390] Vacuum tube question

[Kenneth G. Gordon]

> When looking at the spec's for a tube what is more important as an indicator of
> it's output,  plate dissipation, or grid dissipation?

Of its output capability? Plate dissipation. Grid dissipation only 
comes into play if you are running it very heavily Class C and 
driving the snot out of it.

For most tubes, you can raise the power output by increasing the 
plate voltage (and current).

 For a tetrodes or pentodes, you can increase power output by 
raising screen voltage, even at lower plate voltages. However, 
screen grid dissipation comes into play and one must be careful of 
that especially in various linear modes.

For pentodes, suppressor grid dissipation can become important if 
you are running positive voltages on it. Most circuits call for the 
suppressor grid being connected to the cathode, so then it doesn't 
become an issue.

Ken Gordon W7EKB