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

[Geoff]

Glen,

The current capability is not the issue. The DC component of the final
saturated the iron in the core.

That's why a previous poster suggested restacking the E-Is to permit an
air gap.

-John


** Or use a choke and capacitor.

Carl
===========



> Don't know about the link! However, I have used power transformers from
> tube type television sets for modulation transformers without any
> problems! At least for transformers in the 100-watt output range. Run
> the center-tapped high voltage secondary to push-pull modulator tubes and
> use the 120 VAC primary in series with the plate/screen voltage.
>
> Does the impedance always match? Of course not. However, no one told the
> transmitter that the impedances didn't match so the power transformer
> worked fine as a modulation transformer. The older power transformers had
> plenty of current capability and, at least in those that I used in the
> 1960 time frame, no problems what-so-ever.
> 
> Glen, K9STH
>
>
> Website:  http://k9sth.com
>
>
> ________________________________
>  From: Leslie Smith <vk2bcu at operamail.com>
> To: ARC-5 List <arc5 at mailman.qth.net>
> Sent: Friday, April 12, 2013 3:32 PM
> Subject: [ARC5] Using a power transformers as a modulation transformer.
>
>
> 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.
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