[Amps] 813 INPUT CCT

[Cliff Lindsay]

Hi all you experts, have been meaning for some time to upgrade the tuned 
input cct on my two 813’s in gg. Am going to try the cct by ZL1AXB using 
a copper coil with the wire inside paralleled with a 900pf or 
thereabouts air cap. Sure you have all seen it. Now if I put a nice 
graduated scale for the cap, to record the relevant tuning points, what 
is the best way to tune it. Am thinking of the explanation by Vic 
Rosenthal, strapping a resistor equal to the input impedance of the 
tubes across the cathode to ground.

So do I put a good SWR meter in between the solid state set and the 
linear and adjust the variable cap for min SWR on each band and mark off 
the points on a scale on the variable with the linear switched off ?. I 
have had the odd triple bi-pass and the memory is just not what it was.


Cliff G4VJI MAIL at CLIFFLINDSAY.PLUS.COM