Since a 220 pf capacitor with ½" leads self-resonates somewhere around 150
MHz., you might want to do the old "put a variable capacitor between screen
and cathode and tune for minimum squeeg" trick. All you are doing is making
a series resonant circuit with the stray inductance of the tube and the
variable capacitor to short whatever nasties you don't want out.

Jim


"Tim Wescott" wrote in message
...
Tim Shoppa wrote:
N9WOS wrote:


Even a 1nF chip cap soldered directly between the screen lead and cathode
of the tube would have the internal tube lead inductances to contend with,
so you're probably never going to 'get there from here' by that method.

I wonder if a loading resistor in the screen lead instead of the grid
would work?

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com