[Amps] transformer winding

[Paul Decker]

Hello amplifier experts.

I'm trying something new, I'm going to attempt to rewind a transformer and am looking for advice.   I'm starting with a microwave oven transformer.  There are a couple of reasons for me doing this:

1.  show my younger generation EE's that you can re-purpose and reuse things
2.  prove to myself I can do this and that it will "work"
3.  have a little fun and use things that have been sitting around collecting dust.
4.  Get my 250W  1296 MHz amplifier running. 

I need to have a secondary of between 900 to 1050 to produce between 1200 to 1400 VDC  anywhere between 0.25 to 0.4 amps should be sufficient for the 3cx100A5 it will be powering.

I've cut the welds on the E-I core and removed the primary and secondary windings.  In the process I've nicked the primary which I was going to reuse.

Those familiar with the MOT's know that most of them have the primary below the secondary and there are shunts.

Since I've nicked the primary, I plan on rewinding the primary but using the entire surface rather than having the windings separated top and bottom.  I'll then wind the secondary on top of the primary.

Q1.  Does this sound appropriate to change the design from top-bottom to use the full E portion?
Q2.  What sort of paper insulation should I use between the primary and secondary?  Where can I get this?  I do have some Kapton tape I could use?
Q3.  I only nicked the first 5 windings of the primary, since I will have a custom ratio, is it OK to simply remove the 5 nicked windings and adjust accordingly or is removing 5 windings too much?  I can simply splice in a piece of new wire.

Q4. I won't be grounding the secondary to the E core like was previously done so I assume I will need some insulation between secondary windings or will the new secondary enameled wire be sufficient for the approx. ~ 1KV?

I know the E-I core of the MOT is not the best, but I'm using it at a significantly lower power level than it originally was in service for.  Besides, this is a learning project, the idea to use what I have on hand rather than buy new "stuff"

Any other thoughts, comments, or advice?


thanks,
Paul
kg7hf