[time-nuts] Re: Source of small quantities of teflon insulated thermal wires for cavity heating?

[Jim Lux]

I don't know that I've ever seen PTFE insulated resistance wire. 10-50 meters is pretty long, so you probably can't do it by sliding a PTFE sleeve over the wire. 
I have seen references to wire that is 377 ohms/square in antenna testing, but I'm pretty sure that was "fabricated by the experimentalist" using something like "space cloth" (paper with a 377 ohm/square resistance). 

You could call or write a company like MWS (https://mwswire.com/). They do custom wire all the time in all sorts of weird configurations. They definitely have resistance wire (about 20 different kinds), and I know they do custom coatings (the data sheet says bare or insulated), but I don't know about PTFE.  They sell PTFE/Polyimide tubing from Elektrisola Medical Technologies.  

They definitely do small production runs (although it might be expensive).  

PTFE insulated wire in general is easy, so if you can find a company that does the "coating" they should be able to do a run with whatever wire you want.   

An interesting problem.  FWIW, a more common way to make heaters like this is to combine flat conductors with a substrate. Either evaporate it on with a mask, or coat a whole layer, then etch it. Adhering to PTFE is kind of a problem, but they could probably roll a flat sheet, lay the foil over the top, etch the right pattern, then lay another sheet, and thermally bond it as a unit. I'd think that something like polyimide (Kapton) would be more common.


On Tue, 6 Feb 2024 15:01:43 +0000 (UTC), Ulf Kylenfall via time-nuts <time-nuts at lists.febo.com> wrote:

Dear time nuts.
In need of teflon insulated kanthal or NiCr wire for cavity heating.

Are there any known sources that can supply quantities in the order of 10-50 meters?
Regards
Ulf KylenfallOnsala, Sweden.


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