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My need to experiment, I might test a little more before calling it done, though you're in pretty good stead where you are, and could just keep it as it is. My thought process, but take it with not just a grain but a helping of salt...id test swr on simplex 15-21, and again on the repeater channels. If it's tending downward on as you go up in simplex, and rising as you go up the repeater Channels, you're likely pretty close, and your lowest swr is in the gap between simplex and repeater frequencies. If you're in that dip and the repeater channels (overall) are higher swr than the simplex, you could probably take a small amount more off to bias it a tiny bit more toward the repeater channels. If the repeater channels are already lower swr than the simplex, or the top of simplex (22) and the bottom of the repeaters (15) are about the same, I wouldn't take any more off. And if I'm off base, by all means, let me know...I'm approaching from a logic/theory side of it, and know the real world doesn't always follow, and I'm always willing to learn. I know my 5/8 wave laird instructions said I should trim a good 3/4" to be centered where I want it, but nanovna and swr meter said it was almost spot on as is.

I would be very happy with those readings. Try different channels and get readings on those so you have an idea of the bandwidth of the antenna.

I forget if I posted it here or on one of the FB groups (I think here), but one test I did was coiling the cable vs just winding the extra around the room...though I atwont say that no effect is possible, least in my case (unmarked Midland mag mount cable), coiled together had a negligible effect on swr...I'll see if I can find the post. That said, since you'll be up there anyway, not a bad thing to do, especially as you secure it. Getting the extra height is a bonus too Edit: went digging for the post and found it pretty quick in the swr meter thread. .09 change on one channel, .01 on the other, and no change in the middle. https://forums.mygmrs.com/topic/2426-decent-cheap-swr-meter/?do=findComment&comment=27863&_rid=2738

Some quantitative data for the antenna mavens (of which I am not) to analyze from our contacts this morning: According to Google Maps we are 22.9 miles away driving distance, which will be slightly less as the crow flies; due north/south from each other; with the western portion of the Angeles National Forest between us. I am transmitting 18 watts with my Anytone AT-779UV (a/k/a Radioddity DB-20G) through my Comet CX-333 triband antenna on my 2nd story rooftop. I hear you better simplex than I do through the 650 Contractor's Point repeater. I hear you just as well, with 3 bars out of 10 on my meter, whether you are transmitting on 462.550, 462.625, 462.650 or even 467.650 (with me listening on the 650 repeater input). So I would suggest unless anyone has something different to say, that you should not cut anymore off, as you will degrade your SWR on GMRS/FRS Channels 1-7 and 15-22. The only caveat I have, is that if the other users of the 650 repeater object to the amount of noise you bring in with your audio, and since this seems to be the only repeater you can hit in the LA area, you might want to improve your SWR on 467.650 (or obtain a separate Yagi optimized for 467.650 and aimed at Contractors Point). Strangely enough, I am unable to hear you with my Comet attached to my Icom IC-R7000, which has much better sensitivity than my Anytone. I cannot explain this at this time, pending more experimentation.

SWR 1.7 is ok. Nothing to write home about, but not terrible. The difference between low and high power measuring usually (but not always) points to a crappy SWR meter. Surecom, right? I would not sweat over it too much.

I would say you are good to go. Now try it out and see what it can do. I run the same setup as you have but my antenna is in my attic. I get about 8 to 12 miles from base to mobile radio and I've reach repeater 30 to 50 miles away but those were big commercial repeater systems.

Monday improvements and update: Rod cut to 8-7/16, on 462.650 (my nearest repeater)at 1.67 swr for high power, 1.22 for low power. Manufacturers specs say 460 cut to 8-3/4 and 465 cut to 8-1/4, so I imagine that's about the best I can do. Should I just leave it be or take it down a tiny bit more?

No, but you will find some GMRS capable gear at a hamfest. If there is one near by, it’s a great source of parts, coax, connectors, towers, and much more, let alone radios. And it’s a good place to do some networking.

This also fits with the growth within a hobby. Realistically, we probably don't start out with the best equipment right out of the gate,we build our toolbox...something decent to start with, and improve, sometimes incrementally. A project here, a project there. We can learn some from others, but there's no substitute for your own experience. Some aren't fans of the Surecom meters, and I don't know that they're the most accurate thing out there, but mine have agreed pretty well with each other, and with the little I've played with it, agree pretty close with the nanoVNA as well. Given the variety of sellers across the sites, maybe there's some variance in quality?

That is one of the beauties of the radio hobby and a serious enthusiast who has test equipment. You get to theorize, experiment and observe the results to your questions first hand. Quite wonderful and fun indeed. Michael WRHS965 KE8PLM

So...conveniently, I have a 5/8 over 5/8 wave Browning UHF antenna and Midland mag mount sitting idle right now, since the truck is in the shop. Dug out the Surecom (sw102) and got some numbers. Stuck the antenna/mount in the middle of the top of a chest freezer (nothing within 6 inches of the vertical, and only wood/sheetrock any closer than a foot to the sides). First round, all 15 (or 17, I forget) feet of cable was kind of lazily run around the floor to avoid any coils. This yielded 1.0 swr on channels 1 (462.5625) and 22 (462.725), and 1.06 on Repeater 22 (467.725). Second test, I coiled as much cable as I could between the radio and the antenna, ended up with 7 coils approximately 5 inches in diameter. Same channels/frequencies as before showed some minor change, though the cable routing near my computer screens and metal monitor stand to get the straightest routing (and most excess cable) might also have played into it. Second round numbers (with the coiled cable) were 1.09 on 1, still 1.0 on 22, and 1.07 on Repeater 22....still well within good swr range, all of them.