[ARC5] Using a power transformers as a modulation transformer.

Bill Cromwell wrcromwell at gmail.com
Fri Apr 12 18:37:03 EDT 2013


On Sat, 2013-04-13 at 06:32 +1000, Leslie Smith wrote:
> Dear List-members,
>  Bry Carling has a pointer (or link) on his web-site, thus:
>  " How to make modulation transformers out of old power transformers -
>  by WA1HLR, Tim"
>  
>  This link does not work.
>  Power transformers don't work (usually) as a modulation transformer
>  because the (transmitter final) DC current saturates the transformer
>  core.
>  I would be interested to get information about using a power
>  transformer as a modulation transformer.
> I would be interested to hear (or read) about the relationship between
> frequency response and quality of "iron" in the transformer.
> 
> 
>   73 de Les Smith
>   vk2bcu at operamail.com
> 

Hi Les,

I did not do it but I recall an article that has your take the
laminations apart - the E shaped and I shaped sheet metal plates that
make the core. In the power transformer those are interleaved. In the
finished, modified transformer all of the E pieces are together and the
I pieces are together. The I's are replaced across the open ends of the
E. They maintain a small gap with something like a piece of waxed paper
(or teflon or mylar tape?). That might send you off on a wild goose
chase, refresh somebody's memory and they have a copy of the file or it
might be completely unrelated.

I looked. I did not save a copy as modulation transformers are not
needed in CW transmitters (evil grin).

73,

Bill  KU8H



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