>
>i have a 4cx1500b which i want to operate as a triode, mainly to avoid
>messing with screen and grid supplies.
A screen supply for the 4cx1500B consists of a string of 5w 20v zeners
with a high value resistor going to the B+. This is essentially the same
circuit that Eimac recommended in its SSB book in the 1950s. Grid bias
suppllies are a piece of cake since they supply 0mA. I would much rather
do such than mess with 9 g-g tuned inputs using a certain Q.
>What does the grid dissipation become
>when strapping screen and control grids together?
The control grid typically takes 75% of the total grid current, and the
screen takes 25%. . On a 4-400A, which has 10w grid dissipation, this
is no problem. Your tube has 1w of allowable grid dissipation.
> How does one determine the
>bias voltage in the absence of data?
Obtain cathode bias from a string of diodes. Tap string for stated ZSAC.
> Whats are the pros and cons of doing this?
4cx1500B goes kaput due to too much grid dissipation.
>
ciao, Pino
- Rich..., 805.386.3734, www.vcnet.com/measures.
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