Re: Re-winding a NST

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Peter Lawrence by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Peter.Lawrence-at-Sun-dot-com>

Shad,
     I'm doing the same thing, with 9, 12, and 15 kv units. Your math looks
right (I did a similar thing to estimate the existing primary turns, put 120v
into the primary and measured the output of 10 turns of hookup wire wound
around the primary). see other comments interspersed.
-Peter Lawrence.


>
>Original poster: "sundog by way of Terry Fritz <twftesla-at-uswest-dot-net>" 
<sundog-at-timeship-dot-net>
>
>
>Hi All,
>
>  Some quick questions about rewinding this thing, so I get it right.
>
>I'm using the original primary, but need to make 2 new secondaries for it.
>It's a 9/30, and I have a 9/60 to do later.
>
>with 8 turns of THHN wire on the core, with 8v into it, I get 38v on the
>primary leads.
>
>1 volt per turn means I have 8*38=304 primary turns.  Sound feasible?
>
>Mkay.  At 9k output, I have 2 4500v secondaries in anti-parallel.  I got to
>remember to wind them in opposite directions.


Make them identical, and flip one around when assembling them on the core.


>
>4500/120=37.5:1 necessary ratio for each secondary.  With 304 turns on the
>primary, I end up with ~11,400 turns on each secondary.  I'm not concerned
>with getting the voltage dead on, just in the ballpark.  I'm going to stick
>as close as I can to what the manufacturers (9/30 is Magnatek, 9/60 is a
>franceformer) originally had on it.  If anything I won't be able to get as
>many turns as the manuf. and it'll have a lower output voltage.  I'm not
>concerned with core saturation, as I won't be trying for more than 9kv out,
>or feeding it more than 120v.  And if it does saturate, ahwell!
>
>For potting!  I'm planning on using vaseline, possibly with LDPE melted in
>with it.  I want to simmer the tranny in the gunk for awhile to give it a
>chance to seep into all the airspaces it can.  HV oil is just too messy for
>my taste, and I can't be bothered having to clean it up.  petroleum jelly
>pretty much stays put once it solidifies.


Don't mix anything into the vaseline, LDPE will not "mix" with it even if
melted. (I'm sticking with xfrmr oil, and making clear acrylic cases for mine).



>
>I wanted to check and make sure I did the math right, so I don't spend an
>hour or two working on it to end up with a "Doh!"
>
>Along the same train of thought, I'd like to use 2 identical cores, wind
>them with heavier wire to be single-ended (what's the technical tranny term
>for a 1 eared polepig?) and run them back-to-back like MOTS for a mini-pig.
>That's a project for another time tho.
>
>	Shad
>
>
>