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Re: If you had this supply and switch, what would you build?



Original poster: "Mike" <induction@xxxxxxxxxxx>

Hi Dave,
Yea, been there, done that. Used a Lepel 2.5 Kw induction heater running ~425 Khz, tuned it with the tap bar to run lower until it ran close to the secondary freq also adding different sized balls to secondary top.
That worked, then added feedback by coupling the grid coil to the secondary so it tracked better.
Cw was nice but Had 120 Hz ihum in arcs, they don't filter heaters very well, so I added a 25 HY filter choke and filter caps to the B plus and got a real clean RF off the coil.
It did tend to get warm after a while though (the secondary). Was wound on a couple of 5 gallon plastic buckets taped base to base as a form. Of course that was a tube type machine.
Mike
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Sunday, April 17, 2005 10:11 PM
Subject: Re: If you had this supply and switch, what would you build?



Original poster: David Speck <dave@xxxxxxxxxxxxxxxx>

Guys,

I've often wondered what would happen if you just connected an appropriately sized primary to the unmodified output of the induction heater, and then added a Tesla secondary. Wouldn't you have pretty much a complete VTTC? It seems like that's all you'd need, or am I missing something? Big induction heaters come up frequently on eBay, and can be had for little more that shipping costs. Would the typical output frequency of an induction heater be too low for decent TC performance?

Has anyone figured a maximum size limit to a VTTC? I often wonder if you could get one of those 10 or 20 kW Eimac triodes off eBay and drive it with a farm of MOT's with a 12" x 60" secondary. Has anyone tried making something like this? Would there be personal risks due to a high CW EM field?

Dave


Oh yes, I would most certainly use water cooling. More, I would use a Corona ring around and tapered away from the water cooling hose say 10 inches; I would likely use 3/4 inch CU tubing for the primary for the hose non-conductive, wind the isolation hose rated at 1 kV /Ft into a 30 ft hose trap well spaced.
So there is the primary, cooled with distilled water and isolation hose.
So, that takes care of the special requirements, from there it's on to what would you want to configure the rest as using the latest computer modeling. Operating cost is not an issue, there is plenty of 480, 3 phase to run it. That service drop has 7 MCM 500 lines in parallel, per leg, running to it. Don't view it as an induction furnace, just it's 20 kV at 30 amps CCS supply floating across 40 Mfd cap bank for high current pulse delivery. So this is to be a DC Switched coil. Just a chance to play "What if" on a supply one usually can't get onto but here it is, just a fun design exercise.
Mike