[TowerTalk] Fwd: 75 or 70 Ohm twinlead or ladderline cable - doesit exist?

[GARY HUBER]

Isn't old fashioned. ordinary lamp (zip) cord about 75 ohms?  A long, long 
time ago, I used lamp cord for low (100W) power.


73 & DX,
Gary - AB9M

-----Original Message----- 
From: Hans Hammarquist
Sent: Sunday, March 30, 2014 4:57 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Fwd: 75 or 70 Ohm twinlead or ladderline cable - doesit 
exist?

The problem boils down to what dielectric or in this case what insulation 
you can find for your wires. Teflon insulation is good but expensive. I 
don't know the characteristics of "regular house" wires. I guess that PVC 
might not be too good and I have no knowledge of the newer insulators. I 
wonder if it is possible to make a Ladder Line with small enough distance 
between the conductors to get 50 - 75 ohms impedance. Somehow I think it is 
not feasible although air as an insulator will have low losses.


Hans - N2JFS



-----Original Message-----
From: Rick Stealey <rstealey at hotmail.com>
To: towertalk <towertalk at contesting.com>
Sent: Sat, Mar 29, 2014 12:10 pm
Subject: Re: [TowerTalk] 75 or 70 Ohm twinlead or ladderline cable - does it 
exist?


So it looks like we have an alternative to coax or open wire line to feed a
dipole for example.
If I took, say, #14 stranded, and twisted it, it would be a good match for a
center fed dipole, low loss and not a high SWR so it would present a 
reasonable
impedance on one band, at the output of a tuner or transmitter.
Sounds good.  However, the savings over coax isn't REAL great.  $50 for 500 
ft
of THHN $14 at Home Depot, means 20 cents a foot for a pair.  Maybe the 
weight
would be less than RG8X.
What about the power handling ability?  Would it take maximum legal power 
(1500
watts in USA, before someone reminds me it's lower in G-land!).
What about using this type of line for a long run to a beam?  It is 
obvioulsy
VERY flexible.  Would the feedline radiation/reception be good enough that 
it
wouldn't upset the yagi pattern?

Rick  K2XT


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