The paint pot would be more likely to have a gasket that would seal both pressure and vacuum. A compressor from a refrigerator, freezer, or dehumidifier will work well as a vacuum pump to keep the costs down. I doubt vacuum would harm an unsealed transformer or a motor. Some Tektronix oscilloscopes have a high voltage transformer that absorbs moisture and fails until it is heated and dried out. I am wondering if putting it in a vacuum chamber covered with a dielectric oil, heating it, and then drawing and relieving the vacuum a couple times would draw out the moisture and impregnate the coils with the oil and keep moisture out.
B. Gentry, KA2IVY
Hi
If you head over and get a “paint pot” at the big box store, they are good to at least 50 PSI. Theyalso come in bigger sizes (for more money …. how odd … :) ).
Same deal, works with pressure or vacuum.
If yo want to go “one step up” get a good vacuum pump and put a heat pad under the whole rig.Things will get *very* dry.
One side note: With any vacuum approach fancy or simple: you also will find out if anything inthe radio is “unhappy at altitude” …. not 100% sure that is the sort of research I would dive into.
Bob
On Sep 22, 2026, at 3:14 AM, Jim Whartenby via Milsurplus <[email protected]> wrote:
When a pressure cooker is cooking, it has about 15psi on the inside pushing out. When used as a vacuum chamber, the 15psi is on the outside pushing in. Evidently, the aluminum container can't tell the difference! <grin>Jim
Logic is a systematic method of coming to the wrong conclusion with confidence. Murphy
On Monday, September 21, 2026 at 04:50:31 PM CDT, Facility 406 <[email protected]> wrote:______________________________________________________________
On 9/21/2026 13:19, Jim Whartenby via Milsurplus wrote:
> One way to easily remove water vapor is with a vacuum. One can easily
> convert an old pressure cooker into a vacuum chamber for perhaps under
> $30 if you already have a hobby compressor / vacuum pump. The holes in
> the cover are national pipe threads so just remove the old hardware and
> substitute a vacuum gauge, ball valve and a tubing adaptor along with a
> new gasket seal. Plug any unneeded holes with the appropriate NPT
> plug. I use a small Gast air compressor / vacuum pump with good
> results. This example will hold a decent vacuum for well over a week.
I've thought of that in the past, but have been worried of the bottom
imploding.
One idea I had was to bolt an Al plate to the bottom, something maybe
3/8" thick.
Kurt
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