10X the plate Load resistance at the lowest operating frequency is plenty.
Check it for series resonance
Not sure if I get this right...
For instance:
The transmitter buffer/amplifier will be a 6146. At 500volts I recon it's plate wil draw approx. 75mA.
the buffer/amplifier plate resistance will be approx. 6500 ohm
So 10 x is 65000 ohm
X=2.pi.f.l
65000 = 2 x 3,14 x 3500000 x l
l= 65000/21980000
L=0,00296
L=
2,9 mHThe same calculation comes up with
5,7mH when used on 160m (1.8 mHz)
If I use the calculation on the negative grid impedance with 150 volt and 10mA, I'll have to use a choke of
65mH at 3,5mHz......
I'm sure I'm doing something wrong here, since most of the schematics call for a "standard" 2.5mH pie wound choke in the various leads.....