I have my antenna 4 feet above roof level and have 50 feet of coax coming down through the roof to the attic to my channel master distribution amp.
In the Arizona brutal sun I believe the coax cable should be insulated so now I am thinking some type of sheath material. Maybe like a 3/4 inch rubber tube that the coax can be pulled thru and add that important cover, keeping the coax cable out of the direct sun, maybe
like water drip line tubing?
TIA 
Sounds like a lot of trouble and not sure it would help.
When I was active in Amateur Radio, I know we used military grade coax in the repeater installations. I’m sure their specs accounted for extreme heat, considering the cable was used in the middle east.
Chas
Putting it in any kind of tube is just going to make it hotter. Just get good quality outdoor rated coax instead.
Yes, the 50 ft run of HQ rg 11, this guy explains the best coax cable
As…@Flyingdiver eluded to i think, Good quality cable should be fine in the extreme heat exposed to sun. I will just replace the 50 ft run in 5 yrs.
Nonmctubber over @Highdefforumn.com
"If you have a very long run of coax, Rg-11 will offer less line loss than RG-6 because the the center conductor is a larger diameter wire.
The second thing to look at is the coax grade, outdoor is meant to be placed in the elements or buried in the ground, and indoor grade, has to be run indoors. Then I have heard some mumbling about quad shielded but I understand little of that. And I have also head that black is the best color for outdoor grade coax. The other thing I have head is the coax line losses increase with the frequency of the signal, so if you have many high UHF stations its far more import than if you have mainly VHF.
In terms of my real world practical experience, the antenna hooked up to my house when I bought it was wired with decidedly inferior Rg-59. When I made my upgrades for digital, my set up became 35’ of hard to retrofit with RG-6, RG-59, that gets into my basement, then to a splitter, one side of the splitter feeds one TV connected with 50’ of indoor Rg-6, the other side of the splitter feeds my other TV that is connected by 75’ of RG-59. Until I added a distribution amp ahead of the splitter, the TV fed with RG-6 got 2 channels more than the TV fed by RG-59. And the distribution amp not only gained 2 more channels, it also equalized reception for both TV’s. I could easily replace my indoor RG-59, but why bother"?