[TowerTalk] How to solder aluminum braid coax cable ?

[Roger (K8RI) on TT]

They had RG-6 size cable between poles?  Around here it is 3/4" between 
poles.  The drops are RG-6 size with foil plus braid shield.  Like most 
RG-6 size they use copper plated steel for the center conductor.  When 
running trunks they use huge 1000' spools of 3/4".  A few were dropped, 
denting the outer layer.  (they threw them away) I had a 1000' spool, 
minus maybe 100 feet.  It is a solid Al shield, no PVC jacket. The 
center conductor is larger than 1/8th inch (Never measured it ), Copper 
plated Aluminum.  Virtually all companies in Mid Michigan areas us 3/4", 
bare Al for trunks.   It's far more rugged than the half inch which 
kinks easily.

For many years I used the 3/4 inch for long runs.  Tower and antennas 
were over 300 feet from the house.  Out of the original spool, I used a 
lot, gave away a lot, and still have a few hundred feet left.

The less than 100% shield has little to do with power and a lot to do 
with signal leakage both in and out.  I think most RG-6 size is "rated 
the legal limit up through 10 MHz with a 1:1 SWR.  I don't think I'd 
trust it at that power level for long.  OTOH, I've run the legal limit 
through 8X up through 40 meters and a "reasonable SWR < 1.3:1 with no 
problems,  I tried CNT250, which is good coax, but it is nor nearly as 
flexible with the solid center conductor compared to the multi-strand 
Copper center conductor of 8X.  The center conductor kept breaking in 
the wind on the feed lines to the center fed, half wave, 40 M sloping 
dipoles.  I've had no failures using 8X with a foil plus braid shield.  
It's very flexible and sturdy

73

Roger (K8RI)


On 1/16/2015 3:45 AM, Yan (XV4Y) wrote:
> Hi,
>
> A few years ago the cable TV network of the city went bankrupt.
> They left kilometers of then unused cable on the poles.
> Yesterday, the telephone company guys did some clean-up on the poles (they are really messy so it was welcomed) and threw away trunks of coax cable.
> I took two runs of around 10 meters each, just in case.
>
> The cable is Chinese made, and the only roman characters inscriptions are SYWV 75-9.
> Doing a quick search on internet you'll see its official spec are reasonably good with 2.3dB/100m losses at 50 MHz.
> It's a 75ohms cable made for up to 1GHz signals. (right choice for cable TV, isn't it ?)
> PVC insulation, PE foam dielectric, copper center conductor BUT aluminum shielding...
> http://bainatong.en.alibaba.com/product/540256967-200746290/CCTV_CATV_cable_SYWV_75_9_9C_FB.html
>
> Braiding is very low density (not for high power transmissions) but I will use it with 100W anyway.
> I think it should be a good replacement for the RG-6 alike cable I've been using for the 20m verticale with fair success.
>
> However as the braid is in aluminum, I wonder if any of you as some advices on how to solder it ?
> I've been using the cheap RG-6 cable TV a lot when good 50ohm cable was not available.
> However, soldering the braid (and at time the coper coated center conductor) has always been tricky...
>
> Thanks for your help.
> 73,
> Yan.
> ---
> Yannick DEVOS - XV4Y
> http://www.qscope.org/
> http://xv4y.radioclub.asia/
>
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-- 

73

Roger (K8RI)


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