[Amps] Quad Tube 4cx800 hf amp

[Steve Thompson]

Leigh S. Jones, KR6X wrote:
> http://www.tomstubes.com/4CX800A.htm for a data sheet
> 
> You've got some problems.  First of all, the tube is good for 2 KV DC and 
> pushing it to 2.6 KV would not be recommended.  Secondly, the output 
> capacitance is not nearly as high as you imagine (9-13 pf).

I've checked a number of ceramic valves when in situ in a chassis, and 
the C from anode to ground is usually around twice the data sheet value. 
For a 4CX800, a couple of inches away from the sidewall of a box, I got 
21pF.

Steve