Thanks for your explanations Charlie es Tom. I guess return loss is the opposite of what it sounded like to me. At any rate, you've explained why it varies inversely with SWR.
Next question: in the manual the ALT IMPEDANCE explantion uses a 4:1 transformer example, which I get. I've been toggling between RG213 50 ohm and rg6/u 75 ohm to observe differences, reasoning that if I use a 75 ohm feeder and get 2:0:1 or lower SWR values, the 50 ohm "system" would start (end) at the rig instead of the antenna feed point. I noted that the SWR bumped up a bit when I added a 120ft transmission line, which I would expect. Am I interpreting alt impedance feature and results correctly? I don't have a single piece of 50 ohm that long but have long pieces of brand new CATV rg6/u from a hamfest jackpot. In chapter six on Transmission Lines in Low Band DXing the suggestion is to use a half-wave section of 75 ohm to aid the match. I have enough rg6u and a 941E tuner if needed to do this. BTW this whole exercise is mostly intended as a lab session for me and a way to get into top band quickly with a temporary antenna. I expected before - and after looking at the FFT pattern have certainly confirmed - that a flattop half wave dipole at 50 feet over rocky ground is not going to work out as a DX antenna. But it might be good enough to allow me to NCS a Tuesday night follow-on cw net after my regular net on 7.117, 0000z Tuesday nights. Hope to be in business by Stew Perry contest. 73, chuck -- de AB1VL NAQCC #6799 ab1vl.com _________________ Topband Reflector Archives - http://www.contesting.com/_topband