holden7471 at msn.com
Sat Feb 18 15:13:41 EST 2012
You can't readily cut the tempered glass without de-tempering it. It will
most likely shatter into a gazillion tiny pieces. The normal procedure with
tempering is to form/cut the glass BEFORE tempering. But the glass panel
can certainly sit behind a smaller opening. Good idea for watching those
nice tubes, plus the metal mesh adds some shielding to the opening.
From: Wilson Lamb
Sent: Saturday, February 18, 2012 11:24 AM
Subject: Re: [Boatanchors] Plexiglass
Being an admirer of my own advice, I decided to check on this. Not many
people would salvage old microwave ovens and even fewer would admit it, but
I do, having finished six now. I'm after the transformers, two of which
will make a KW power supply, but there are lots of other things in there
like microswitches, hardware, and quite a bit of nice hookup wire. I'm no
longer taking everything, since I have enough, but did have a carcass in the
basement with the door still on.
The door has a piece of probably tempered glass backed up by a panel of
perforated metal with thin plastic laminated on.
This was a classic, old, high end unit, for over the stove use, so a little
larger than some. the glass is 19.25X7.75 inches, so needs cutting if for a
standard panel. I'm guessing a regular glass cutter would do it. The
perforated metal is quite heavy gauge and would make a great viewer for the
old rig, as well as let in air. It's a panel screwed into the door, with
the perforations inside the frame part, so you'd have to trim the perforated
part out with a saber saw.
I wouldn't be surprised if modern units are a little simpler, but don't
know, since I recycled the other five, doors and all. You can likely break
off the door at the hinges, if you don't want to bother going inside.
BTW, of the six HV xfmrs, two are a good match and the rest scatter from
1900-2600V! You can use the filament winding to buck or boost the voltage
by about 2%, if you have a pair that are close. These are cheap xfmrs,
optimized for the oven service, so they draw about 4-5A with no load. The
power factor unloaded is 0.1, so it's not many Watts and doesn't seem to
create heat, to speak of.. You have to use two, because one end of the
secondaries is grounded and may not be sufficiently insulated to run above
ground if lifted.
There's a ref or two I'll provide if anyone wants, or you can search the QST
archive for microwave oven.
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