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Hi all. I have installed my GMRS radio in my 2015 Jeep Wrangler Sport a couple of months ago, but I have not gotten around to setting it up to be used yet. I will need to have my radio working by July for the NJ Jeep Invasion, and I am not sure how to get everything working properly. To help you understand my set up, this is what I currently have: Midland MXT275 MicroMobile Two-Way Radio. It is attached to a Quadratec Quick-Disconnect Mount for a CB Radio (I believe it's the JK-CBMU), which I modified slightly for the GMRS radio. The mic is hanging from the Quadratec CB Radio Mounting Bracket #CBM-75WX11. Larsen Low-Profile Unity Gain Antenna #LP450NMO on a Midland MXTA12 Magnetic Mount, which is positioned center on the crossbar, and clears my soft top. I ran the cable of the magnetic base from the center of the crossbar to passenger side B-pillar, down the B-pillar, and under the molding for the front passenger door toward the file firewall on the passenger side, where it cross over under the dash and back to the radio. This is similar to how Jeep ran the antenna for the SiriusXM antenna, as well as the GPS antenna if equipped. Since I no longer use SiriusXM, I remove the SiriusXM antenna at the same time I was running the antenna cable for the GMRS radio. It is my understanding, similar to setting up a CB or other communications radio, that you need to tune or trim the antenna for proper operation and to avoid any damage to the radio. So my question is, how does one tune or trim the Larsen Low-Profile Unity Gain Antenna? I have searched for information when I have had spare time, but so far, no luck. I also heard that I should not use an SWR meter for a CB radio, so if someone could recommend a SWR meter for a GMRS set up, I would greatly appreciate it.

I am a new GMRS licensee. I am making an ammo box repeater & have a question about the Larsen NMO 2/70. It was given to me by a friend whose Dad was a longtime ham. I know it is a dual band 2 meter/70 cm antenna with the coil in the middle. I’d like to cut it down to GMRS only, but my antenna analyzer doesn’t do UHF. Has anyone done this, and what are the whip lengths? I plan to use the 462.725/467.725 pair, so the 462 frequency would need the lowest SWR. Each of the two elements are currently around 15 inches each.