http://elecraft.85.s1.nabble.com/What-your-mother-didn-t-tell-you-about-transmission-lines-tp6780383p6781639.html
A quick warning about actually using zip cord for feedline. The typical
etc. It is almost always some PVC based formulation. Zip cord has been
famously LOSSY and wholly unsuitable for feedline. At one time I did see
time. It seemed to measure a fairly reliable 84 ohms, and I have been able
up well to Mother Nature. Just use the very small tie wraps (UV resistant
stuff) to keep the two wires together every six inches or so. I did NOT
> 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:
[hidden email]
> > [mailto:
[hidden email]] On Behalf Of Jack Smith
> > Sent: Monday, 12 September 2011 1:01 AM
> > To:
[hidden email]
> > 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.
> > > ______________________________________________________________
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