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Re: heating cable sources



 >Our resident APD wire expert (who also will chime in if he wants)
 >thinks Dupla probably special orders the stuff. A minimum run would
 >involve many hundreds of feet with the bottom line having 4 digits.

That would be me :-) Yes, I do think Dupla has their cable specially made. 
It is a heavy-walled silicone-insulated wire similar to UL Style #3239 
(high voltage silicone wire), but with a resistive element inside that 
looks like nichrome and some nylon/spectra (not sure which) fibers 
presumably to prevent stretching from breaking the conductor. I haven't 
been able to find it, and my distributor who was looking for it is going 
out of business (stock tip: sell Anicom while you can ;-) My rep is moving 
to a new company though so the search continues...

If there was interest I would consider a special run from one of the custom 
wire manufacturers, but the minimum order is about 50 *thousand* feet. 
That's a *lot* of tanks. One could probably outfit even Dupla for a while 
with that much.

For now I have been recommending Teflon-insulated (PTFE) wire since it will 
not absorb water and will not deteriorate if immersed over a long period of 
time. It also handles very high temperatures (200+ ºC) OK which is a 
definite plus in this application. It unfortunately has thin insulated in 
most cases, so you have to be careful with it. Specifying 1000v wire will 
get a bit thicker insulation, but not much. You can get it in small 
quantities from Mendelson Electronics in Dayton OH (http://www.meci.com) in 
26, 24, and 18 awg. Dan's source is http://www.worldwidewire.com but has a 
$100 minimum (am I right here Dan?).

Power supplies are easy to build with a transformer and some fuses. Lots of 
DIY info is available on the Krib if you are looking to construct your own 
cables.

	-Bill