Hi Stan: Post ten.
There are two ways to approach this, just put something up, or measure and optimize. When using the KX3 ATU, both methods will provide similar results. An 88 foot Doublet and feedline is modeled using EZNEC and SimSmith. The results found here: http://www.kn5l.net/Doublet88/ The Balun, both 1:1 and 4:1 is modeled with a perfect conventional transformer block "A." The KX3 ATU is modeled with the L-C network block "LC1." A five foot RG-58A/U between the Balun and KX3 is added. For modeling, Wireman 551 is used and tuned for optimal results on 40 and 20. As shown, a 1:1 Balun results with the best match with SWR below 1.5:1 on both 40 and 20 at the KX3. With system loss below 1 dB. For this antenna, other bands will have a better match with a 4:1 Balun, with loses below 1.5 dB. What is shown is that there is only about 0.5 dB difference between the optimal and just put it up approach on 40 and above. Using a BL2 and switching between 1:1 and 4:1 depending on the band. A short antenna will have a very low impedance, causing the additional feedline loss to increase significantly, Greater than 4.5 dB is for 80. John KN5L ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
