[AMRadio] Transformer help

[Gary Schafer]

Thanks for the response Bill. What I was trying to find out was if the
particular transformer was rated  220 or 120 volts. It has no markings and
only a single wound primary. I did find out how to check. By applying voltage
with a variac and monitoring the primary current for a rapid increase which
would indicate core saturation. If it made it to 220 volts without saturation
(about 250 ma current draw) then it was ok for 220 volt operation. If the
primary was intended for 120 volts it should saturate at around 150 volts.
Current would rapidly rise to several amps. I tried this with a small filament
transformer (rated for 120 volts) also and indeed found that it would saturate
at around 150 volts.

Speaking of choke input, I wonder if a swinging choke only, will cause
problems on SSB. The supply that the transformer is going into has a 20-4
henry swinging choke. It was used that way before but I am not sure it is a
good idea. I seem to remember from the early days that a swinging choke was
not recommended as power supply dynamic regulation would suffer badly ?

73
Gary  K4FMX




wwd at netheaven.com wrote:

> Resend: Did this get out to Gary? Anyone? (testing, testing) .   .   .
>
> Putting 240vac on the full primary will get you via a solid-state bridge
> (choke input) about 3400 vdc. Which is probably just what you wanted for a
> 'big' rig. I'd insulate the core from the chassis with sturdy standoffs.
> Also caution signs since a secondary short to core will leave it hot to
> chassis! Always  go in first with your hv probe! It will probably last
> forever. Good luck. Bill N2KQA
>
> > Gary Schafer <gschafer at mediaone.net> said:
>
> >I wonder if anyone can help identify a transformer for me.
>
> >It is a plate transformer with what looks like a hypersil (sp) core. It
> >has a single primary with 3 taps. Not sure if it is rated for 120 or 240
> >volts. With 120 volts I get 1900, 1770 or 1685 volts out. No center tap
> >on secondary.
> >The only numbers on it are:  AA 3883  and S179027. Do those numbers mean
> >anything to anyone ?
>
> >It is probably mid 70s vintage.
>
> >Also does anyone know how I can tell if it is ok to run on 240 volts
> >rather than 120 volts other than amount of smoke?
>
> >Thanks
> >Gary  K4FMX
>
> --
> -----------------------------------------------------------
> wwd at netheaven.com
> -----------------------------------------------------------
>
> _______________________________________________
> AMRadio mailing list
> AMRadio at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/amradio