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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