"One way to accomplish that at a lower price than a commercial ATU at the antenna is to put in a matching network for each band, relay switched, at the base."
I use a 43-foot vertical for 160-20 meters. The higher radiation resistance (compared to other verticals) helps with antenna efficiency over other than a perfect ground system (I do have a lot of radials, but I know my ground system still isn't perfect). The 1:4 unun at the base gives a relatively low compromise SWR on 40-10 meters, resulting in negligeable SWR-related coax losses if you use good low-loss cable. My worst-case SWR is on 20 meters where it is about 5:1, resulting in only a fraction of a dB loss through my 60 feet of 1/2" heliax. The problem is on 160- and 80-meters where the SWR is very high so coax and unun losses can be high - and matching from the shack is very difficult or impossible due to the high SWR. So I built a relay-switched matching unit that lets me select 160, 80, and 60-10 meters. Actually, I couldn't stop myself until I'd built three different matching units. Details are in the "Articles" section at http://w6rvb.com/ad5x/. 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
