Dave WX7G wrote an article that may be of interest: www.eham.net/articles/21272
I also have some info in the “Presentations” section of my website at www.ad5x.com. As Jim says, if you use good quality coax over reasonable distances (I use 1/2” heliax over a 60-ft run), SWR-related losses are reasonable on 60-10 meters. Above 20 meters the radiation angle increases. However, since the antenna is electrically longer the radiation resistance increases which makes ground losses less significant. Lots of trade-offs to consider. Matching at the antenna base is important on 160- and 80-meters as the SWR is VERY high on those bands. Also, most autotuners cannot match the 43-foot vertical at the base on 160-meters so additional external inductance is needed on this band (see the Autotuner Extender in the “Articles” section of my website. I prefer the convenience of the autotuner in the shack, especially if you use an amplifier. A remote tuner can’t easily take your amp off-line during tuning or if a high SWR suddenly occurs. So I use a fixed base match for 160/80 meters, and the standard 4:1 unun on 60-10 meters (all switchable from the shack). My KAT500 in the shack handles all the bandwidth extensions I need on all bands. Phil – AD5X ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
