[Amps] SB-220 6M conversion

Jim jimw7ry at gmail.com
Fri Jun 5 23:22:15 EDT 2020

Did you directly ground the grids with short wide straps? (best not to 
use braid).

What did you change on the 10/15 meter coil to use it on 6 meters?  What 
are you using for tune and load caps? What is the minimum capactiance of 
the tune cap?

Post some pictures so we can take a look at your layout, tank circuit, 
and the tuned input.

Jim W7RY

On 6/5/2020 10:10 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
> manuals at artekmanuals.com

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