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

[Herbert Schoenbohm]

Telephone C drop wire may work in your case and it is very strong. I 
believe the characteristic impedance is 70 ohms.

On 3/24/2014 4:15 PM, jpk5lad at cox.net wrote:
>  From where I'm sitting, I can see a run of Kilowatt Twinlead running up the wall, into the attic
> and to standoffs going up the tower.  I've used it for years to feed two of my top guy anchors,
> insulated off to be fed at the top.  This KW twinlead was not 75 ohm but was actually 300
> ohm.  When I owned a ham store in the 70s, I bought it from Dentron in a 100' length.
> Dentron offered both the 450 ohm window line and the 300 ohm KW Twinlead through their
> dealers.
> .
> I do remember (I'm from the 1957 era) both a lighter duty 75 ohm twinlead and a much,
> much heavier 75 ohm twinlead although I don't recall ever using it.  Perhaps they were both
> spec'ed at 72 ohms, it's been too many years to remember that particular detail.
>
> Around our neck of the woods, I believe only the 300 ohm heavy and thick twinlead was
> referred to as "Kilowatt Twinlead."
>
> Just musings from another old timer.
>
> 73,
> Jim - K5LAD
>
>
>
> On 24 Mar 2014 at 12:45, Jim Brown wrote:
>
>> On 3/24/2014 11:36 AM, Drax Felton wrote:
>>> It's 72 ohm twin lead.  Also known as zip line.
>> That's a new one on me, and I've been at this since 1955. Back then, and
>> for several decades thereafter, Belden and Amphenol made a product
>> commonly called "Kilowatt Twinlead," which was a pair of AWG #13
>> stranded copper conductors spaced apart by 2-3 conductor diameters by a
>> rather beefy dielectric. My old Belden catalog from 1971 says it's part
>> number 8210, is 72 ohms Zo, 0.67 Vp. I actually have several hundred
>> feet, what's left from a 250 ft spool that I bought "new old stock" at
>> the Milwaukee hamfest sometime in the 70s, figuring that I'd someday
>> find a use for it. 25 years later, I did, and it fed an 80/40 dipole
>> that I also loaded as a Tee vertical on 160M.
>>
>> I also have some junk lengths of the Amphenol product, which looks a bit
>> less robust.  Both products have been discontinued for several decades.
>>
>> Last I looked (about 7 years ago), I think I remember DXE was selling a
>> window line that they described as 100 ohms.
>>
>> 73, Jim K9YC
>> _______________________________________________
>>
>>
>>
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