[Amps] SB-220

Jim jimw7ry at gmail.com
Tue Mar 30 10:48:09 EDT 2021

> Why do you need more L?
> On what band or bands?
> Thanks
> 73
> Jim W7RY
> On 3/24/2021 9:46 AM, Joe wrote:
>> Need advice,
>> I am assuming some of you here are also on the Heathkit HF Amps E 
>> -Mail list.
>> So I won't go into the long drawn out story here unless asked to do 
>> so if needed.
>> I re-built this old SB-220 practically from scratch. And changed a 
>> lot of stuff to make it better.
>> But one change it has been determined, has made it in the Need of 
>> needing more "L" in the output network.
>> That of course if even possible would be some major surgery to say 
>> the least. Trying to think of how I can add some more "L".
>> At 2 AM last night I had a thought. How about like an old Drake VFO!? 
>> Drakes varied the "L" in their VFO's not the "C" as most others did.
>> And they varied it by inserting a ferrite bar into the coil.
>> Research says that inserting Ferrite into a coil will increase the 
>> amount of "L" the coil has.
>> I wonder if I could cheat and do the same on the L7 coil of this amp?
>> Get some ferrites like on a plastic threaded rod and insert them into 
>> the coil.
>> What Mix of Ferrite would be best for such an application?
>> And anyone thoughts of possibility of success?
>> Joe WB9SBD
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