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From: Jim Fosse [SMTP:jim.fosse-at-bjt-dot-net]
Sent: Tuesday, March 31, 1998 11:42 PM
To: Tesla List
Subject: Wood Welder?
All,
I've just acquired a _Wood Welder_ manufactured by
Woodwelding, Inc. Newport Beach CA. Model: ST2000. Manufactured on
3/30/58 (hum, 50 years old yesterday. And in better shape than I'm
in;)
Does anyone have any info on this beasty, I'd like to know more about
it's use before I rewire it into a vacuum tube TC.
thanks,
jim
p.s. I've ask around some, no one has heard of it yet. I've included
some offline emails as background.
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Friday night I picked up a "Wood Welder", its a diathermy machine used
to weld wood. Operates at 40Mc and has 2 hugh (by my receiving toob
standards;) transmitting tubes inside it. (15 minutes later) These
tubes are RCA CRC-833-As. 2 of them in push pull configuration. (I had
to pull one out and wash the saw dust off of it to read the number)
The tank circuit is unique. Standard 1/4" Cu tubing for the center
taped inductor with built cap.
{actually with further inspection the coil looks to 3/8" O.D.}
Take a 9" by 4" box and mount 2 7" by
2" plates 1 inch from the wall. Connect these to the tank inductor.
Now, run the grid wire through the metal box (through the 4"
dimension) about 2" away from the plates. (feedback cap??)
Output is 1 turn of #18? connected to some RG8 sized coax. the coax
then goes to the head where another 1 turn loop couples back into a
1/4" Cu tubing inductor with a butterfly air variable (with about a 1"
plate spacing). 2 insulated metal bars 3" by 1/2" long at each end of
this second tank circuit supply RF to the wood.
I've not powered it up yet. I want to get all the saw dust out of the
cabinet first.
Complete with power supply, control contactor... Input is 115V -at- 15A.
LOOKS LIKE A TOOB TC FOR ME!
I've placed the approximate schematic at:
ftp://ftp.bjt-dot-net/users/jfosse/wood_welder.gif
cheers,
jim
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Hi Guys,
I cleaned up the wood welder and fired her up. OH! boy are
those 833s gorgeous. Even if their filaments are exhausted, I'm gona
use them as table lamps! (the plate current is only 100ma not the
500ma spec'd)
I don't seem to be able to change the plate current using the
adjusting cap in the welder head. I would suspect that the 40 year old
coax has gone south. I can however light ANY gas discharge lamp I
place inside the cabinet. I've lite both an 8" circular fluorescent
lamp and a large decorative "flicker" (C9 sized) neon lamp. There's
plenty of RF inside. Its just not getting outside. My SWR bridge / RF
power meter doesn't even twitch when placed near the welder head.
Also, at times when I move the welder around, I hear some arcing
inside the cabinet. Short or open in the coax??
in Vacuum toob heaven,
jim