[AMRadio] Re: 500 Transformer

[Dave Aabye]

Hi Gary,

Yep, it's a bummer!

WZ1M wants $260 to rewind the existing transformer.  Peter Dahl sells a replacement
for $285.  I think that Dahl offers a better deal because it is a hypersil unit
with a 500 ma CCS rating.  I believe the original is rated 400 ma ICAS.  Only
drawback is the need for 4 new mounting holes.

I replaced the tube recitifiers with solid state units shortly after purchasing the
500 (about two years ago).  I also inserted thyristers in the primary leads to cut
down on inrush current.  I wonder if you have any further protective measures to
suggest.

73 de Dave, W4QCU
Oak Ridge, TN

Gary Blau wrote:

> Dave:
>
> Ouch.  Sorry to hear that.
> Sounds like WZ1M's offer to rewind might be attractive, unless you can
> find another 500 xfmr somewhere (good luck!).  That's a great rig so
> it's worth the investment.
>
> Now, to find out why it went bad in the first place...
> Best of luck.
>
> Gary
> W3AM
>
> Dave Aabye wrote:
> >
> > Hello Gary,
> >
> > Thanks for the suggestion, which I believe has proven to be conclusive.
> >
> > I hooked my Variac to the primary and slowly increased the secondary voltage.
> > The caps were disconnect from the rectifiers, so the transformer was "all by
> > itself".  At about 700 volts, the voltage started to jump just a bit.  At
> > maybe 750 v, the secondary emitted a puff of smoke with an accompanying hiss.
> >
> > I think it is clear that the transformer is shot.  Time to call Peter Dahl!
> >
> > Again, thanks for your input.
> >
> > 73 de Dave
>
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