That stuff is getting harder to find. Used to be CATV companies locally
gave free reign to hams locally to pick through the piles of spool ends; Now
local CATV Comapnies often say no to hams, and let metals recyclers get the
ends. Great, Extremely low loss stuff, the 75 ohms impedance can be dealt
with in various ways, (or even ignored iin a lot of cases)
Your thought of splicing probably should be improved, so as to not produce
large impedance disturbances on the line, especially if using in the VHF/UHF
or higher frequencies.
I have a collection of old EME (moonbounce) Engineering newsletters from
Eimac that shows a lot of examples of large VHF and UHF arrays that were
homebrewed, and needed to work well for Moonbounce. Was surpised to see
one example using a junction of 75 ohm CATV feeders simply strapped all
the shields togiether with hose clamps, with the center conductors simply
extended 3" or so straignt outside the jackets, and strapped together,
soldered, with bare wire.... no impedance matching considerations at all,
on a VHF EME antenna!
If your cable is .75" cable, splice connectors are very easy to make, using
a double female UHF connector, a hack saw, hose clamps, and sealing tape.
The barrel connector center contacts accept the .750 cable center with a
snug fit, and the OD of the barrel is a slightly loose internal fit to the
cable jacket. You remove (dig out with Needle nosed pliers) the foamed
dielectric about 1.5 inches in on the cable ends and push fit the cable
into/onto the barrel after hacksawing several slots parallel to, and
symmetrically around, the cable jacket centerline. The saw kerfs allows
the ID of the jacket to slightly decrease, and a snug fit to the barrel
when clamped. Use dielectric grease between the barrel, and the inside of
the aluminum jacket, and tighten the jacket, using small hose clamps. Seal
the whole thing really, really, well with electrical tape, coax seal,
As I recall, on middle HF freqs the stuff has less than .1 db per hundred
The jacket kinks with permanent deformations easily if you or someone before
you bent the cable
into too small of a radius. Be careful to avoid this..
73, DX, de Pat AA6EG firstname.lastname@example.org;
>From: "Tom Hellem" <email@example.com>
>To: "Towertalk submit" <firstname.lastname@example.org>
>Subject: [TowerTalk] CATV Hardline
>Date: Thu, 14 Sep 2006 20:41:30 -0500
>I have three spool ends of 3/4" CATV hardline, the stuff with the rigid
>aluminum jacket. It was lying in a field for probably upwards of 10 years.
>When you look at the open end, the dielectric appears to be somewhat
>deteriorated, but cutting off 6 inches or so reveals what looks to me like
>it's in good shape. I am contemplating using the stuff for a 300 foot run
>out to my tower, underground. It will need to be spliced a couple times,
>which I would accomplish by briging the cable ends up above ground,
>and soldering the center conductor together and bond the outer jacket, all
>in some sort of weatherproof junction box.
>Does this sound like it could work, or am I just asking for trouble? Is
>there a way to test the stuff? Could it be contaminated and unuseable while
>still appearing to be in good condition?
>Any input would be appreciated.
>Tom Hellem K0SN
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