[Amps] SB-220 6M conversion

[Adrian]

Have you seen this one Steve ?  ;

http://www.arrl.org/files/file/Technology/QST_Apr_2008_p38-40.pdf


On 6/6/20 1:10 pm, Artek Manuals wrote:
> 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 
> difference
> 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?
>
> Dave
> NR1DX
> manuals at artekmanuals.com
>