Re: [TowerTalk] 75 or 70 Ohm twinlead or ladderline cable - does it exist?

[Jim Lux <jimlux@earthlink.net>]

On 3/25/14 4:50 PM, Jim Brown wrote:
> On 3/25/2014 4:40 PM, Tom Osborne wrote:
> > I wonder if we are talking about the same 'twisted pair?'
> Probably not.
>
> > The wire I was talking about was the old telephone wire they had back
> > in the 50's and 60's that came from the pole to the house.  I think
> > most of it was probably number 12 or so copperweld wire.  It had a
> > funny insulation - almost like tarred rubber on some of it.
> I'm talking about twisted pair generally -- much of the world runs on
> twisted pair of one sort or another. Small signal audio typically uses
> #24 - #28, as does CAT5/6/7. Loudspeaker wiring in pro systems uses #10
> - #13, depending on the length of the runs. If I were feeding an antenna
> with twisted pair and didn't care about visibility, I'd use #10 for low
> loss. But if visibility was an issue (i.e., a stealth antenna), #22 with
> a good quality enamel would work for moderate power levels.
That makes sense.. the insulation thickness is probably the same, 
regardless of the wire diameter (within reason), because that's driven 
by mechanical ruggedness and voltage breakdown concerns... a 50 mil 
jacket over a 10AWG wire is very believable and would get you into that 
50-60 ohm range without too much trouble.
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