source for short lengths for 1pr 16-18Ga shielded

Aircraft wire might work, and some of the vendors don't mind selling it by the foot. If there is a larger general aviation airport near you, a repair shop there might also sell you some, as long as you swear it'll never be more than 6 feet off the ground. :) You need to have a good wire stripper to get the insulation off of this stuff.

Various sizes by the foot; more expensive but not surplus:

Using Digi-Key's selector, lots of things top out at 105 C, except for this stuff, which goes to 200 C:

Mouser has some stuff that might be in the realm of possibility. Annoyingly, their selector doesn't include the temperature rating; you have to guess based on what material it's made of. This stuff

Another keyword that might help is "plenum". A lot of the plenum cable you will find is solid Ethernet cable, but stranded plenum exists, and tends to have a slightly higher temperature rating. You'd have to run some of the 24 AWG conductors in parallel, but here's 50 feet for $15, with free DB-9 connectors:

SXL/GXL/TXL wire works well on cars, but I only know about it in single conductors. It goes to 125 C.

Standard disclaimers apply: I don't get money or other consideration from any companies mentioned.

Matt Roberds

....

Doh, I should have thought of Skycraft, I was there a year ago.... Aircraft Spruce never occurred to me...but should have.

He does not want to buy 1000 ft. when he needs 4-5.

Thanks...