Message: 4 Date: Tue, 18 Apr 2017 03:31:59 +0000 (UTC) From: Al Lorona <alor...@sbcglobal.net> To: "elecraft@mailman.qth.net" <elecraft@mailman.qth.net> Subject: Re: [Elecraft] OT; Feedline question Message-ID: <852881305.2998918.1492486319...@mail.yahoo.com> Content-Type: text/plain; charset=UTF-8
If instead of using the relative permittivity of air, 1.00059, for calculations of open-wire line, you use the effective permittivity including any spacers used to homebrew the line, this value will increase slightly. For instance, I am using spacers made of a material called "nylon 6,6 30% glass fiber-reinforced" which happens to have a relative permittivity of 3.9. This has the effect of increasing the effective permittivity between the wires from 1.00059 to 1.08656. Another way of saying this is that the velocity factor goes from 1 (for pure air) to 0.959, or about 96% with the spacers. The effect of this is to make the characteristic impedance of the line drop from around 480 to around 460 ohms. ( See http://www.emclab.cei.uec.ac.jp/xiao/Wire/index.html ) This obsessive exercise on my part illustrates that spacers don't make a whole lot of difference, but they do make a difference. You may want to include their effect or not. Al W6LX OM Al, Thank you for taking the time to share your results on this forum. "That which is not rigorous is meaningless.".......Attributed to Blaise Pascal The results may not be significant or even of minor interest to many, but how would we know had this work not be done and presented here. 72, Tim Colbert K3HX ____________________________________________________________ "Better Than Adderall" Pill Now Legal For Your State Residents Health Tips Daily http://thirdpartyoffers.juno.com/TGL3131/58f62a48922102a474f94st04duc ______________________________________________________________ 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
