MarkInTampa

Keep in mind that maritime users ARE allowed (even digital!) on the GMRS repeater input frequencies of 467.550 and 467.575 per ITU (not FCC) regulations but not the outputs of 462.550 and 462.575. They may affect (as they do in my area) the input of a 550 or 575 repeater mixing in with legit traffic even if on a different tone causing a bit of chaos on the output.

Like I said, your results may vary. The SWR on mine (again 2m/70cm version) is less than desirable on GMRS. However the GP-6NC GMRS version has as close to perfect SWR on GMRS (what it was designed for) as you can get and has a decent SWR across 70cm and 2m as well.

The GP-9 2m/70cm antenna sucks at GMRS, at least in my case. If you have a SWR meter or VNA test it out yourself, your results may vary....

You are about dead on on power loss. 59% according the the calculator, but with the gain of the antenna you have an effective radiated power of almost 200 watts. Keep in mind the tool I used (https://kv5r.com/ham-radio/coax-loss-calculator/) uses dBd for antenna gain, dBd = dBi - 2.15

I put a loop at the antenna because the Comet instructions tell you to do so. I figured if it is in the instructions, there is a reason why.

I did a tone scan and got a tone a few months ago when it was transmitting DMR and tried. Either analog is disabled or it's using a non-standard input. I did think about running a simplex repeater to mess with them but not worth the effort.

Here is one of them https://flscg.org/2021/03/tampa-gmrs-repeater/

It's close to impossible to hijack a encrypted DMR repeater that doesn't do analog.

Not in this case. The NXDN repeater went online six months ago, the P25 repeater has been online for a few years. I'm not complaining, both are really strong repeaters (the most dominant in the area) and most traffic is analog. If there is a bit of digital traffic a few times a month for a minute or two, it's a small annoyance for how good the repeaters are. The encrypted DMR repeater on .700 popped up a year or two ago. It was traced to a security company running illegally and has been reported to the FCC many times but it's still there.

Tampa has two digital/analog repeaters on GMRS, one running P25 and the other NXDN. The connection info is published on their websites and are public. Neither one of them get very much digital traffic, I would guess 95% is analog. There is also someone running encrypted DMR on 700 still, from what I was told it is a business running GPS tracking on fleet vehicle's. It drove the Tampa 700 repeater a year or so ago to .600 and they forced the existing .600 repeater in Clearwater to .550 knowingly but didn't care.

The largest public repeater in my neck of the woods doesn't show up on the map anymore. From what I was told is if the repeater owner/operator doesn't check in with myGMRS within 12 months the repeater is removed from the map. It's still listed (with the map) if you go the the list view and click on it. The owner just got tired of repeater requests so he publicly listed the tones, called it open and disabled access requests and hasn't updated the status in over a year.

It died down but never went away in my neighborhood. One is still linked but doesn't have nearly the traffic it once had but still a lot of out of state traffic.

I've had pretty good luck with the Argent. I originally bought it so I could hook it up to the base station and test HT's and antenna's out in the wild without needing somebody on the other side and it did a excellent job of that. Since it does CW-ID, I loaned it out to a repeater operator to send out the CW-ID through a HT to the repeater until he got a new controller. Also use it on occasion to repeat voice back to the repeater for radio checks if somebody wants to hear what they sound like through the repeater. But most of the time it sits in a box unused, but a nice tool to have when you need it.

The GP-9NC (GMRS/MURS) is rated 153-157MHz and 460-470MHz. The straight GP-9 and GP-9N (ham version) is rated 144-148 and 440-450MHz.

I have both of these antennas. 30ft mast, 50ft LMR400. In my case, the GP9 worked better on VHF and the GP6 better on UHF. Don't know if it is the location of the antenna, the oak tree 20ft away or what but I had a better experience with the GP6 over the 9. I dropped my mast to 15ft and the GP6 made it just fine though the Cat3/4/5 hurricane that hit me last week in Tampa. Don't have to worry about the oak tree....it didn't. Power is still down, no air conditioning sucks.