[AMRadio] open wire line


jeremy-ca km1h at jeremy.mv.com
Mon Nov 19 18:03:46 EST 2007


Geoff, the actual line impedance you use isnt an absolute; anything from 
300-800 will work equally well.

#12 spaced 4" is approximately 550 Ohms.

Carl
KM1H


----- Original Message ----- 
From: "Geoff/W5OMR" <ars.w5omr at gmail.com>
To: "Discussion of AM Radio in the Amateur Service" 
<amradio at mailman.qth.net>
Sent: Monday, November 19, 2007 5:52 PM
Subject: [AMRadio] open wire line


>I tried to get on the air a few days ago, and noticed the SWR was extremely 
>high on my loop, fed with ladder line.
>
> After much futzing it finally dawned on me to check the loop for 
> continuity.  There was none.
>
> The 450-ohm ladder line I've been using for two and a half years, before 
> it broke, is 14ga solid copper-clad steel wire. Not conducive for windy 
> (read: outdoor) applications.
>
> So, my solution is going to be to home-brew an open wire feed line, using 
> insulated 12ga stranded copper wire.
> I will still be using the same SA-2060A tuner that's carried me for years.
>
> I'll probably go down to the local hardware store and get either some 
> wooden dowel rod, and chop it up to equal length pieces and cut a slot at 
> the end of each, spray 'em with urethane (for weather protection) and then 
> 'hot-glue' the wire/dowel in place.  Or, get some plexiglass rod and do 
> the same thing, minus the urethane spray paint.
>
> My question is:
> how far apart should the two wires be kept?
> I've seen as little as 4" and as many as 6", and both claim to be ~600ohm.
>
> The 450-ohm ladder line is only about 2" wide.
>
> -- 
> Driving your AM Rig without a scope, is like driving your car at night, 
> without headlights. (K4KYV)
>
> --
> 73 = Best Regards,
> -Geoff/W5OMR
>
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