[Amps] SB-220 6M conversion

Artek Manuals Manuals at ArtekManuals.com
Fri Jun 5 23:10:41 EDT 2020

I have enough HF amps here (four at last count) One of them is an 
ancient SB-220 , so I thought what the heck I would "hack" it and turn 
it into a 6M single band. I have a folder  full of articles on how to 
from the last 20 + years.

All done "physically" but try as I may I can not get more than about 
600w out .

1) Two different tank circuits , one with a section of the original 
10/15  coil from the SB220 and a 2nd one with a a piece of flat copper 
strap ...no difference
2) Changed the parasitic chokes
3) Tried  "T" input match. Pi input match , straight through ...no 
4) Plate voltage is 2400 unloaded and about 2050 loaded in CW position
5) Bias measures 6V
7) Has new Hardbach bias and diode and metering board
8) Older set of Eimac 3-500Z and newer set RF Parts 3-300ZG ...no difference

What am I missing, ?
What else to try?

manuals at artekmanuals.com

Manuals at ArtekManuals.com

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