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Re: [Amps] SB-220 6M conversion

To: Artek Manuals <Manuals@ArtekManuals.com>, "amps@Contesting.com" <amps@contesting.com>
Subject: Re: [Amps] SB-220 6M conversion
From: Adrian <vk4tux@gmail.com>
Date: Sat, 6 Jun 2020 13:24:14 +1000
List-post: <mailto:amps@contesting.com>
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@artekmanuals.com

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