[Amps] Some thoughts about FL-2100 and SB-200 work in 6m

[Hsu]

A few month ago, I  have discuss with a friend about a pair 572Bs work in 
6m,in usually, the people don't think some PAs like FL-2100 and SB-200 what 
with 2X572Bs can not work  in 160(80)m-6m,   6m only.
  I have some thoughts about these PAs, maybe can modify and let these PA 
work in 160(80)m to 6m . 1) add a relay and swicth in/out  6m input network 
indendently and let the wire  what connect to the cathoude as short as 
possible.
don't modify the exist input network.2).I do know 572B with long lead.
to add a  FR4 PCB   or metal sheet what with two  holes in the top of tube 
's  base/bottom of  anode(actually  insert the tube into the holes)  , 
connect / solder   the sheet /PCB  to ground . this  sheet  for shield 
cathoude/anode.
3)in 6m band , duo to the 572B's large capacitance, you can not get 
resonable QL,if cut the  plate capacitor,and regard  the tube 's output 
capatance +stray capacitance as plate capacitor(fixed), insert a shorted 
copper circle in  the coil
to turn the PA like 
http://www5a.biglobe.ne.jp/~jh2clv/gu74b2m/2mplatecoil030920.jpg. this can 
solve the problem what 572B's large  output capacitance 
problem.3)certainly, the neutralization is needed.
  I do not have FL-2100 and SB-200, If you interested, maybe you can try to 
add  6m band and HF bands still usuable.
Any suggestion?
   73!Hsu