I note that the subject of counterpoises has been debated many times in this forum but I have not seen the subject of tuneable artificial grounds discussed. As no doubt many are aware, operating from a location remote from the ground has its problems in ensuring effective grounding, especially with end fed wire antennas. I have this problem as I operate from an upstairs shack. I have overcome the difficulty by using a tuneable counterpoise arrangement in conjunction with my end fed wire antenna. The EFW antenna is approximately 66ft (20m) long and the counterpoise wire 16ft (5m).
Using my homebrew AGT and my KX3 is a simple process to tune for resonance. a) Tune to the desired frequency using the internal KX3 auto tuner. b) Tune for maximum current using the AGT meter (low power recommended for tuning). Repeat the process as necessary to obtain best match. Usually 1:0 or 1:1 (KX3 reading). I only operate with 5 or 10 Watts. Apart from overcoming grounding problems you get a resonate grounding system not an approximately resonate one as used in most circumstances. This in my view, is a suitable compromise in overcoming difficult grounding conditions, although I do not advocate it in preference to an extensive grounding system where conditions permit. One point to note is that if an external power supply is used the output must be isolated from ground and suitable precautions taken against lighting strikes. Many designs for simple homebrew AFT projects are available on the web and MFJ also do one commercially. Obviously different or different multiple lengths of counterpoise wires can be used to get the best setup with your antenna. 73 Stan GW3SRM ______________________________________________________________ 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 Message delivered to [email protected]
