[Milsurplus] DIY Vacuum Chamber

[Brenda Gentry]

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. They
> also 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 in
> the 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 
>> <milsurplus at mailman.qth.net> 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 
>> <facility_406 at bruteforcedevelopment.com> 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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