[Amps] SB-220 6M conversion

[Jim]

Good article except for tearing out the original relay. Not necessary, 
unless you want to use QSK or hate the sound of loud relays (like I do).


Thanks
73
Jim W7RY

On 6/5/2020 10:24 PM, Adrian wrote:
> 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
>>
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