ok so ive been running 2m and 70cm off a discone that's been sitting in the attic for like 3 years and honestly it does the job but i keep wondering if i'm leaving a lot on the table. finally decided to get a proper dual band collinear up on the roof, probably a Diamond X510 or maybe the X300 if i can't justify the cost difference right now.

the run from my shack to the roof is going to be somewhere around 60-70 feet, maybe a bit more depending on how i route it to avoid the HVAC stuff. i've been going back and forth between LMR-400 and just using RG-8X to keep costs down. i know RG-8X isn't ideal but at 2m it should be okay right? or am i just being cheap and it's gonna hurt me more than i think at 440?

also anyone dealt with getting coax through a tile roof without making a huge mess of it? there's a vent pipe up there i might be able to run it alongside but not sure how watertight i can get that

at 70 feet on 70cm RG-8X is gonna cost you something like 3-4 dB compared to LMR-400, rough ballpark. that's not nothing, especially if you're trying to hit weak signals or work through a repeater that's already marginal. on 2m it's a lot more forgiving, maybe 1.5 dB or so over that run. honestly if you're doing a permanent roof install just bite the bullet on the LMR-400, you're not gonna want to redo the coax in two years because you went cheap the first time. the X510 vs X300 thing is real too -- the X510 has more gain on paper but it's also got a really narrow vertical pattern so if you're working local stuff and there's any terrain between you and the repeaters it can actually work against you. i've seen people go back to X300 after putting up the X510 for exactly that reason.

for the tile roof, i've seen people use a split-loom tube with self-amalgamating tape where it enters, not perfect but it holds. the better solution if there's a ridge vent is to run it under the cap tiles but that really depends on your roof type.

yeah what he said about the coax loss at UHF is pretty accurate. i ran RG-8X up about 50 feet to a jpole years ago and it was fine for 2m but 440 was noticeably worse than my buddy running LMR from the same area. not scientific but you could hear the difference.

the tile roof thing -- honestly i'd just hire someone if you're not comfortable up there, those roofs crack so easy and a cracked tile turns into a leak turns into a whole thing. i know that's probably not what you want to hear but ive seen guys spend more fixing the roof than the antenna cost in the first place