I don't know anything about radios so these questions may be dumb! I appreciate your patience. I am continuing my project to install a HF radio on my steel boat. I have a now bought a used Icom M802 and an AT-140 tuner. I have set it up at home to test it and it works! I know the two frequencies I am most interested in using: 7.268 and 14.300 MHz. The AT-140 antenna tuner will tune anything, and it is now connected to a random wire hanging from a tree to simulate my mast. But I was thinking... First question: If I'm operating at the same power, on the same frequency, with the antenna in the same position and configuration (hanging from a mast), a resonant antenna cut for the frequencies I want should perform better than a random length of wire tuned with the AT-140, other things being equal, right? (Is this true?) Some of the mariners on various forums think so and what they do is essentially use the AT-140 as the center connector for a dipole. They connect one wire of the dipole to the AT-140 "antenna" port and one wire of the dipole to the AT-140 "ground" port then turn on the AT-140 "THRU" function (deactivating the antenna tuner) when they are on the resonant frequency. They report success. So I cut two wires to what I thought was the right length and tried this, but I cannot figure out how to measure the SWR to trim the wires with the equipment that I have. I have an Ameritron AWM-35B SWR/Wattmeter (just bought it). When I key the mike to transmit at a low power level to measure the SWR with the AT-140 shut off ("THRU"), the SWR meter always starts to rise then it stops at about 1.2 and goes back down again. The Icom display then reads "SWR." The "REF IND" light comes on the SWR meter. I'm guessing the Icom is shutting off the transmission due to the SWR. My issue is that I don't know how to measure the SWR because I tried 8 frequencies spanning 2 MHz to 30 MHz and they all produce the same behavior and the same reading. When I have the AT-140 on, I don't read any SWR and the radio works. Am I misunderstanding how to measure SWR to trim the dipole or is there something wrong with my whole plan here that I am not seeing? Alternately, I was thinking I could take the AT-140 out of the center and use a more traditional dipole center connector, but OTOH it feels like I should test it as close to the actual boat configuration as I can. I have a patch cable from the Icom M802 to the SWR/Wattmeter, a 50' RG-8X running from the SWR/Wattmeter to a MFJ-915 line isolator (1:1 ferrite choke), then a patch cable to the AT-140 feed. The antenna wire is 14 AWG stranded copper. Boat layout in case relevant for antenna ideas: Another option would be I could raise two antennas and buy an antenna switch, having the AT-140 only on the non-resonant antenna. If that would be better for some reason let me know! I was trying to avoid two antennas. I've tried figuring this out on my own but I think I know too little about the area to make sense of the things I am reading/watching. The boating forums strike me as full of weird theories and conflicting information so I thought I would try the ham forums. I really appreciate any help!