Extreme High Voltage: Supplement: Vacuuming a Coil under Mineral Oil

Here I’m trying my version of MakerJ’s home-built HV transformer built on a flyback core ferrite.

I’ve made the coil itself, about 10 wraps of #27 magnet wire, each with around 80-90 turns, each layer separated by 6 wraps of brown masking paper, very similar to newsprint but unbleached and of course not printed.

I probably should have terminated the coil before vacuuming impregnating. But I was so eager to get started vacuuming that I just went ahead and dumped the non-terminated coil in there. Oh well, somewhat of a mess awaits me, and then another session under vacuum, I suppose.

I’m using the Harbor Freight 2-stage vane pump, which is supposed to pull down to 30 microns. It is sold for use in automotive air conditioning service and works very well for the price (under 200 dollars) and is small and very portable. It is also a clone of a common small pump so it should be possible to get parts, if they are ever needed.

I’ve had that small jar of DC high vacuum grease for thirty years; we used to use it in the aircraft industry to lubricate and waterproof spark plug connector inserts. DC-4 is preferred now for that purpose but it’s not as stiff as the HV grease.

Music is You Keep Showing Up, By Jingle Punks, from the YT free audio library. Thanks Punks…er… folks !

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