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Re: NEON- eddy coils /induction heaters
In a message dated 96-09-08 14:48:32 EDT, you write:
>
>>I keep seeing you talking about your eddy coil quite matter of factly.
>>can you share more info on this. I have an induction heater that's
>>pretty good, however I am looking for others. I have a coil wrapped
>>around some U shaped ferrites. This eliminates have to seal the
>>tubulation through the coil. Let's get an HF discussion going.
>>
>>Jacob
>
>How many turns? what freq? Dou you have the ferrite info?
>
>Dirk,
>Is your eddy coil "gun" open like a U?
>
>
You're right, this is interesting. When I first got started, I tried to use
my old trick from my flashlamp days, using a conical-shaped concentrator
"gun", but it didn't work so I went back to basics and used coils, but it
could be much better if this were worked out again, it would avoid a lot of
hassles positioning coils on the bench for each tube. My previous bomber used
to be 20kW, however, and now I have to do with a 1kW, that may make all the
difference.
Okay, this is how an RF concentrator works. (God, when are they going to have
a toolbar on AOL Mail?) First, imagine a sheetmetal can, about the size of a
coffee can, out of copper. One end of it is wide open, and the other is
almost closed except for a small hole in it. Now also imagine a straight
split of about 1 mm in this can going along the edge all the way from top to
bottom, and then continuing along the almost-closed end. This is like a
one-turn solid secondary of a transformer. Then, wrap copper coils around the
outside of the can, with asbestos insulating them from the can, about 6-10
turns depending on how you want your load to match, and this is something to
play with. The bottom turn should be brazed or soldered to the can but in no
way should you short out the can by crossing the split or allowing a short by
the second turn to the other side of the split. The ends of this copper coil
are connected to your bombarder.
This will produce a current amplifying transformer for your bomber that will
concentrate the RF power into a very small space. The small hole in the
middle of your concentrator now focusses the RF energy into that small
aperture, and that's where you get the most power.
Now, a gun can be made by changing the configuration a little, by making the
cylindrical can into a cone. (With a handle and a little switch in the
handle, you will look and feel like Buck Rogers with his ray gun.) At the
small end of the cone, hollow out a cove so you can fit the tip around a
cylindrical object and go halfway around it. This will definitely not work
with a 1kW supply since I already tried it but will get your electrodes nice
and cherry red if you have a larger supply. Someone else can supply more
details perhaps. I don't know if this would work with a 2.5kW supply.
I would also like to hear more from anyone with experience in very high
frequency RF supplies like the kind that can heat glass. Get the drift?
Jeff Golin
Neon Express