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Thanks gman. I’ll look into that NanoVNA.

Thanks Lscott. That’s exactly what I’m seeing after some more testing today. With the LMR-400 cable I was able to get the SWR to 1.58 with some tweaking and it’s still good (actually a little better on high power) with the RG-58 cable on the factory mag mount base. Sad note on the Midland MXTA26. As seen on multiple reviews they almost cut the whip antenna a bit short. I had to raise it to the highest level that the Allen screws would still hold it to get the 1.5 SWR.

Thanks. That’s info I was looking for. I’ll check that out. It’s the Midland MXTA26 and it didn’t come with any length instructions in the package but I’m sure I can find them online. I didn’t adjust anything initially for the antenna used on factory supplied mag mount that came with the radio that used RG-58 because the SWR was 1.01 and it functioned OK. Based on the factory cable specs it calculates to losing about 2.7 dB over the length of the cable. It was then I tried some better LMR-400 cable and that was when the SWR jumped to 2.3 for the midland antenna. I’ll be using it to transmit on GMRS frequencies only so it may indeed be too long and need some trimming so I’ll look into that. Thanks again.

Thanks. Yeah, I don’t have anything to measure impedance at the moment. I’ll have to try and come up with something. That’s something on my I need to get list. I figured higher loss cable may dissipate some of the reflected power but needed a second opinion. Thanks.

I’m relatively new to antenna tuning and am wondering about coax quality effects on SWR. Here is my situation. My setup: I picked up a Midland MXT 500 along with a Midland MXTA26 antenna. They are both good in the original configuration and I get good range to a HT. SWR is 1.01 on GMRS low channels and 1.38 on higher power channels? Next I picked up a base antenna for the house with 25 ft. of LMR-400 cable and get 1.03 on low and 1.48 on high channels. I’m good with that. Here is where I start chasing the rainbows: In the pursuit of more actual power actually being transmitted, and since the Midland magnet mount antenna uses 20 ft. of some “high loss” RG-58, I have the urge to use some better cable and ditch the magnet mount since my truck would permit using a 10 ft. run of LMR-400 with very minimal bending. My issue: I did some testing of the Midland MXTA26 antenna using the 25 ft. of LMR-400 that works well with the base antenna, but I’m getting a SWR of 2.8 with the Midland Antenna and a one piece UHF to NMO adapter used for a Jeep mount setup. I did use a 12 inch disk as a pseudo ground plane but it made no difference one way or the other. The question??? Would lower loss cable cause the SWR to increase from 1.01 to 2.8 requiring the antenna to be tuned a bit. The only thing I cannot test on something else is the UHF/NMO adapter but there is nothing to that and everything ohms out good. Id hate to do any antenna modification if it won’t work anyway.