[TheForge] Microwaving Metals From the Virtual Junkyard

Tue Jan 6 09:00:01 2004

Greetings:
	FTG here, shared space with the 10 and others (which I have
forgotten<G>).  CA-148 Newport News

Understand.  A specially formulated crucible sounds in the order.  =
Problem
is that a crucible, thus heated, will radiate heat equally in both
directions, both inside and out<G>.

As simple as these ovens are, opposite walls could be taken out and =
replaced
with copper mesh (McMaster Carr).  We've done similar things here, so =
that
we can look down the throat of high power feed horns under full power;
looking for arcs<G>.  The mesh would allow air flow through the oven for
cooling. But as I write this, if there were refractory material =
installed
inside, the heat could be used<G>.

Side note, funny story.  Another building was going to throw out a bunch =
of
tubes, including a large number of magnetrons.  I snagged them and put =
them
in my office.  Shortly thereafter, the adjacent office (which included a =
ME)
had problems with his monitor.  The computer dudes were called, changed =
out
the monitor, and he still had problems.  They were confused.  But as =
they
pulled the monitor out to check the connections, they noted that it went
back to normal.  The question was, "who's office is on the other side of
that wall?"  They went into my office and rearranged material so that =
the
magnetic field interferance went away.  Next day, I entered my office, =
noted
the hole in the array of magnetrons, and put one back in the hole.  =
Almost
immediately the fella came in and asked me if I had moved some =
magnetrons.
He asked me not to put one in a particular position as it was seriously
messing up his monitor<G>. =20

As the Brits say;;;
All the best

-----Original Message-----
From: [email protected] =
[mailto:[email protected]]
On Behalf Of James Binnion
Sent: Monday, January 05, 2004 9:28 PM
To: [email protected]
Subject: RE: [TheForge] Microwaving Metals From the Virtual Junkyard

Hi Grover,

I used to be a radar tech (SPS-10 and BPS-15) many moons ago in the=20
Navy and also worked on induction furnaces .  I did not want to get=20
too technical about it in the last post (probably because I have=20
forgotten what I used to know about magnetrons) but the fellow who=20
did the first work that I know of using microwave ovens for melting=20
tried graphite crucibles and found them to be too conductive. His=20
working crucibles were mixtures of ferrite and magnetite with a=20
graphite fireclay binder this provided a good impedance match to the=20
radiated energy from the magnetron and got real hot. The biggest=20
problem is getting rid of the radiant heat given off by the crucible=20
so that the oven doesn't melt or catch fire.

Jim

=20