Ah, but Sandy, it's so reminiscent of the old shipboard installations! I can hang a neon or fluorescent lamp on the antenna where it exits the shack and it'll blink as I pound the key, just like Sparks did, Hi!
But, yes, "direct feed" antennas that come into the shack require care to insulate and isolate the high RF voltages. And there are frequency/power/distance-from-human limits to observe to meet the RF exposure regulations. I use a big manual L-net tuner for my end fed wire. AFAIK, all Elecraft tuners use L-networks. Ron AC7AC -----Original Message----- This particular "technique" using a half wave antenna as an "end fed" wire can be VERY dicey if you run high power, but as Ron says the efficiency rises as the ground losses fall. (Percentage wise) A way to get maximum use of a 100 watter or a QRP rig when your space available is small. Somewhere is this thread of discussions the "balun" is mentioned, especially the 4:1 one. IF you are using a 4:1 "transformer" type balun (the ones commonly wound on toroid forms) Losses MAY be high and also destructive to the balun if there is a large of amount of inductive or capacitive reactance the "balun" is dealing with! Do not assume the reactance is "low" unless you have measured it as such at the frequency of operation! "Choke" type baluns usually escape this "destruction" (burning up, overheating, core shattering, etc.) more easily than the transformer types! Don't forget one of the simplest networks there is, the "L" network, is also sometimes the most efficient yet devised. Most of the automatic type tuners are based on a multielement switching "L" network. 73 to all, Sandy W5TVW ______________________________________________________________ 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
