Thanks guys. I've made open wire/ladder line before and will be doing so again for a planned vee-beam array, but I've never tried twisted pair other than UTP for Ethernet (most people call it "Unshielded Twisted Pair" but I guess "Unified" or "Uniform" would make sense too).
Years ago I used copper zip cord/bellwire for make-shift portable dipoles (just knotted the centre point to stop it all unzipping!) - worked well enough with an outboard toroidal balun and ATU in the K2 for a few QSOs while on holiday in the South of France. There were better things to do than play radio! The 120 ohm impedance of zip cord should be a close-enough match for a fullwave loop. 73, Gary ZL2iFB > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Jack Smith > Sent: Monday, 12 September 2011 1:01 AM > To: [email protected] > Subject: Re: [Elecraft] What your mother didn't tell you > about transmission lines > > A few years ago, I measured a length of plastic (some form of > vinyl, I > believe) insulated zip cord with the loss results below. > > Impedance over the range 300 KHz - 30 MHz varied from 118 > ohms to 124 ohms. > > Jack K8ZOA > > > Frequency MHz Loss (dB)/100 ft > 5 2.3 > 10 3.5 > 15 4.6 > 20 5.5 > 25 6.9 > 30 8.1 > 35 8.7 > 40 9.2 > 45 10.4 > 50 11.6 > > > > On 9/11/2011 8:20 AM, Bill W4ZV wrote: > > Fred Townsend wrote: > >> Rubber (parallel) lamp cord can be used as transmission > line and it is > >> cheap. Z0 runs 95 to 120 Ohms depending on insulation thickness. > >> > > True, but it has very high loss (especially at higher > frequencies) and > > should only be considered as a last resort. About 10 years > ago ET3PMW was > > attempting to get on the low bands and only had zip cord > available for > > transmission line. I thought it should work fine for 80 > and 160. However, > > on 80m running 100 watts he was barely detectible here using a 1200' > > Beverage for receive. Once Paul got some good ladder line, > his signal was > > typically S8 on 80m and S6 on Topband, where he made > several hundred QSOs > > with North America even in summer QRN (June/July). > > > > There is a loss graph on page 2 below but I believe > ET3PMW's losses were > > much higher. Of course this could have been due to poor > quality wire > > available in Ethiopia. > > > > > http://www.we0h.us/Amateur_Radio_stuff/Antenna/ZIP-Cord-Antenn a/Zipcord-Antenna-7903031.pdf > > > > 73, Bill > > > > > > -- > > View this message in context: > http://elecraft.365791.n2.nabble.com/What-your-mother-didn-t-t ell-you-about-transmission-lines-tp6780383p6780644.html > > Sent from the Elecraft mailing list archive at Nabble.com. > > ______________________________________________________________ > > 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 > > > ______________________________________________________________ > 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 > ______________________________________________________________ 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
