On 14/11/2020 19:44, michael adams wrote:
Polyethylene and polyvinyl chloride are used as insulators. These two
plastics have relatively low melting points, and can start to soften at
temperatures as low as 150 degrees F. [65 C]

Yes, coax becomes more flexible on hot days, and can be a stiff
nightmare in winter.

If the insulation is exposed to low heat over long periods of time, the
position of the center conductor in relation to the shielding may shift
as the hot plastics yield. If the center conductor and shielding
touch, signal never makes it past that point. Coax should be kept away
from heatsinks, stage lights, and other sources of heat

But my goodness it would have to get damned hot to let the inner
migrate. It would be easy enough to test. Put some coax into a tight
bend and boil it in water for a few hours. I've never done this, but I
can tell you that black coax on a south facing wall on a hot day gets
too hot to touch (I've been burnt) and yet it continues to work.

Bill