[Boatanchors] SP-600 Toroid

[Carole White-Connor]

When it comes to SP-600s, if Andy doesn't know it, it's not worth
knowing! He's the best.

Joe Connor

"Drew P." wrote:

> James,
>
> Thank you for the very specific and succinct
> information.  I appreciate your help.
>
> Drew
>
> --- "James A. (Andy) Moorer"
> <jamminpower at earthlink.net> wrote:
>
> > I rebuild the torroids as follows:
> >
> > I start with a core from Micrometals. A T37-6 or
> > T44-6 will do. If your eyes
> > are good, you could use a smaller one.
> >
> > I wind it as follows:
> >
> > Tap 1 followed by 4 turns
> > Tap 2 followed by 10 turns
> > Tap 3 followed by 4 turns
> > Tap 4
> >
> > The original was 2-10-2, but that doesn't put much
> > voltage on the output. 4
> > turns puts about 1.5 VRMS. Note that whatever you
> > feed it with has to put
> > out that voltage.
> >
> > I then cover the whole thing with epoxy. I hold it
> > to the PC board with
> > nylon washers with a #6 screw and nut.
> >
> > Remember not to twist the wire together when you
> > bring out the taps. That
> > just adds capacitance (bad!).
> >
> > I have restored a number of JX-17's (I'm not sure
> > how many) and I have never
> > seen one without a broken T-35. You can't just glue
> > it together - when it is
> > broken, it also breaks the magnetic circuit. Note
> > that this means that you
> > can't put two standard JX-17's together and expect
> > it to work, since both
> > their T-35's will be broken. With this replacement
> > in both receivers, you
> > can. I have tried it and it works pretty well.
> >
> > I believe the problem is that the torroid was made
> > early in the history of
> > ferrite materials and they didn't take stresses from
> > thermal cycling into
> > account. A little humidity in the air plus a red-hot
> > tube receiver and *pop*
> > goes the transformer.
> >
> > This coil does not resonate - it is just an
> > autotransformer.
> >
> > Hope this helps.
> >
> > James A. (Andy) Moorer
> > www.jamminpower.com
> >
>
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