[Boatanchors] SP-600 Toroid

[Drew P.]

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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