Jumping into the middle of a thread with a single, but useful, comment,
Steve, K9DCI says:



"Gary Schafer" wrote in message
...
On Thu, 26 Jan 2006 19:31:08 -0500, Straydog wrote:



On Thu, 26 Jan 2006, Gary Schafer wrote:

On Wed, 25 Jan 2006 22:09:48 -0500, Straydog wrote:


Since my earlier post (dealing with the question of what is peak
evelope
power output in an AM transmitter), I've been doing more scrutinizing
of tube Ip/Vp characteristic curves. They are much more non-linear
than
the impression you get from just looking at the curves. Also, it is
rare
or almost non-existant to find Ip vs screen voltage!

Probably because the screen and supressor grids are not the main
controlling grids, but are there only to reduce Ip vs. Vp and control
secondary emission off the plate respectively.


Lets look at the venerable 833 (from my RCA TT-3 transmitting tube
manual). This is a KW input class C triode.

From the curve:
at zero grid volts, 1 kV on the plate gives 175 ma plate current
2 kV 500 ma
That's more than a doubling of Ip for a doubling of Vp

at minus 50 grid volts, 2 kV on the plate gives 50 ma plate current
4 kV 750 ma
....

OK OK TWO comments...
I think someone else pointed out that this is a static situation and in a
circuit, the supply voltage and the plate voltage are not the same thing
when you have a tank circuit in there.

73, Steve, K9DCI