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Re: using an SS White x-ray transformer, an AM/FM Tesla coil??

Hi Barry,

Thanks for the info. on "re-oiling" the x-ray transformer (as well as all
the other people who have responded too!).  I was lucky enough to obtain
another one of these transformers the other day, rated at 90 Kv, 14 mA.   I
pulled it from an x-ray head, the tube of which was burned-out.   The only
thing I'm wondering about now is duty cycle,  since these transformers are
normally rated for just a few seconds at maximum output.  Otherwise, I'm
pretty much ready to rehouse them, probably in the same heads where I
obtained them.

That's a LARGE transformer you have, that's for sure!  Where I live, I could
never use one of those, nor could I use a "pole pig" (even though it's very
tempting).  I can only imagine what the generated RFI would do to the
neighbors!  RFI was bad enough during my Ham radio days, speaking of which-
I wonder if anyone's ever amplitude or frequency modulated a Tesla coil?  It
should be possible.

John

>Hi John,
>    Reverse one of the windings and you have 45 kV at 14 mA.  I
>unpotted two neon sign transformers.  I soaked their coils in toluene
>and then ethanol to remove the hydrocarbon residue.  I then laid them
>on a teflon sheet, to prevent sticking, and applied a coat of red
>glyptol, available at electronic parts companies.  The gluptol soaked
>through and formed a barrier that allowed the entire winding to be
>filled with the stuff without leaking.  I baked it at about 150
>degrees F for about a week until it got hard.  Then I peeled it off of
>the teflon sheet.  I put it back on the core and surrounded it with
>teflon sheets.  It has performed well for many years.   I haven't
>assembled the 15 kV, 60mA transformer yet.
>
>    I have an x-ray transformer also.  When I remove it I will soak it
>in mineral oil to remove the old oil and then change out to fresh
>mineral oil.  Above 20 kv I would recommend oil unless you want to pot
>the windings in high thermal conductivity high voltage epoxy.  At the
>higher voltages the insulation gets so thick that thermal problems
>become great.  Oil solves these problems.
>
>    Several times, I have had to refill the oil in a + - 100 kV, 300
>mA, Maxwell power supply after I fixed it (I was having too much
>fun!).  I followed Maxwell's procedures.  They said to let the
>transformers sit in the oil for a few hours (a few days would be
>better if you have the time).  Next, bring the voltage up to 10 kv and
>let it buzz for about an hour.  Next, bring the voltage up to 20 kv
>and let it buzz for about an hour (more of a massive humm-buzz sound).
>This procedure is continued until full voltage is achieved.  I only
>went up to 80 kv as I only used the transformer up to 70 kv.  It
>worked fine.  The combination of the core vibration and the heat
>worked the air out nicely.
>
>Barry
>