Not sure where you all get your coax loss figures but they are way off.
https://www.qsl.net/co8tw/Coax_Calculator.htm
Any considerable length of general purpose coax (LMR-400 and down) is very lossy in the UHF and up spectrum. Heck loss with bonafide hardline gets to be pretty bad at long lengths depending on the size
As a wise old Elmer once said your transmission line should cost more than your radio and antenna combined. Now in his time they didn't have the ability to separate the amp deck from the radio head. But still putting your amp deck 400' in the air on the tower isn't exactly feasible to being cost effective. Maybe it is if you live in a lightning free area and if you do I would love to see a picture of a real unicorn. Now on towers I know they use isolation to keep the equipment safe. But at home at least 80% dont. At home many use long runs of whatever coax they can afford. Ive seen countless YT vids of folks using trucker special. And it works because its just enough signal to hit 2 or 3 local repeaters. Yay the radio gets out!! But does it really? Most everyone goes by what repeater they hit. Try Simplex. You will find it doesn't go too far. Unless a repeater is well over the horizon a couple watts will hit it. But weather can wreck havoc on that. And if you have a 40-50 watt radio on high hitting your antenna thru lossy coax you might only be getting 3 or 4 watts out of your antenna. Yep antenna gain will help but again in this spectrum a flock of birds can block signals. You want to keep that coax/hardline at home as short a possible. If youre going for a repeater it doesn't need too be a mile in the air. The repeater is already there. That's why many an HT can hit them.
Anyhow as usual I drifted off subject. Check your coax calculations. They are much worse than you think. Dont forget to factor frequency and swr. Do nite that oddly RG8 is better on UHF than 213. Velocity factor? That's not 8x but big old RG8. As for reference my antenna is 23ft in the air. I use a 21' foot LMR-400 Coax run. I can hit Repeaters on UHF from 65 miles away. I am on a hill. Not the highest point around but south and east of me is all downhill. To the north is a valley where the city is that lets me bypass it and cover small towns north up to 60 miles UHF and 100+ miles VHF. West Im blocked by my faraday cage built house(no I didn't build it) that even on 2nd floor an HT wont work standing in the windows.(I think the guy who built this house lined his hats with foil). The local GMRS repeater is 4 miles away and a 2m and 440 repeater is 2 miles and cant hit them inside. At first set-up I had my 8Watts HT, 65ft. of RG8X and a Tram 1480 antenna. I could hit tepeaters up to 25 miles on UHF. When I got the Yaesu 50watt radio I gained about 5 miles total. But once I shortened coax to a single run off 21' of LMR400 and moved amp deck just inside garage my ranger increased dramatically. Plus reception of Simplex stations increased 50fold. I have Simplexed 45miles on UHF.
So my point is: Double check your coax loss. You will find its more than you think. Secondly build your base system, unless you are doing your own repeater, to do Simplex. Doing this will give you more repeaters to choose from. Unless you live in a deep valley short good coax is the way to go.
Buzz
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Repeater output power
