On 1/31/2017 3:43 AM, Thomas Horsten wrote:
Depends on your random wire and what band(s) you want to use. For some bands the 9:1 "balun" (not used as a true balun in this case, since both the coax and the random wire are unbalanced by nature) will step the feedpoint impedance down to something that's a better match for the 50 ohm coax, limiting coax losses.
Unless one is using a matching device designed as a current balun, the common 4:1 and 9:1 "baluns" are actually simple auto-transformers. The best approach is an auto-transformer at the feedpoint (with a counterpoise) followed by a true 1:1 current balun (common mode choke). The 9:1 "balun"/transformer may be more appropriate if the "wire" approaches a half wave on the frequencies of interest. However, there is a definite interaction among antenna length, transformer ratio, feedline impedance and feedline length. 73, ... Joe, W4TV ______________________________________________________________ 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]
