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[TowerTalk] Connectors for 75 ohm hardline

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Subject: [TowerTalk] Connectors for 75 ohm hardline
From: k1zat@dsport.com (JD Delancy)
Date: Sun, 15 Nov 1998 18:33:02 -0500 (EST)
Bill -

> I need information regarding making connectors for 3/4" and 1/2"
> hardline to a LMR400/9913 connection. Any ideas will be greatly

For the 1/2 inch CATV I used a reducing compression union, 5/8"
to 1/2" (True Value part 286-738). Cut the plastic coating (if
it has it) back about 1.75".  Cut the aluminum jacket about 1.5
inches from the end of the CATV. I used a plumber's tube cutter
for clean edges. Then strip about 3/4" of the diaelectric away
from the center conductor.  Put the 1/2" nut and the compression
ring over the aluminum jacket. Shove the diaelectric and center
conductor into the compression union just as far as you can,
making sure that the aluminum jacket gets inside the seat of the
1/2" end of the union.  You should have an ample amount of the
center conductor coming out the 5/8" end of the union.  Slip the
compression ring down on the seat of the union followed by the
nut.  Tighten it down.  Take a UHF barrel and shove it on the
center conductor.  Make sure it also engages the seat of the
compression union.  The center conductor should go no more than
halfway into the barrel.  If you have extra on the center
conductor, trim it to make it fit.  Put the 5/8" compression
ring on the UHF barrel followed by the nut.  Crank it down
making sure that things are tight and secure.  When you put it
up on the tower, take either some silicon tape or liquid rubber
with you.  Apply it generously over the entire connection
followed with a good wrap of electrical tape.

The center conductor of the 1/2" I inherited was as a little bit
smaller than the center of the UHF barrel.  A visit to the local
hobby show came up with some fuel line used in model airplanes,
about the next to the smallest size they have.  A piece big
enough to cover the center conducted was soldered in place and
shoved into the barrel. Nice tight fit.

On the 3/4 CATV, that's a different story.  I've been unable to
find a 3/4 to 5/8 reducing compression union, they are
apparently rare (if they exist at all).  I used a 3/4" female
hose thread connector that reduces to 1/2" female pipe thread, a
3/4" to 5/8" reducing male and the compression right and nut for
a 5/8" union. Cut away about 1.5" of the aluminum jacket.  
Using the 3/4 female, start it on the jacket and "score" threads
into the jacket, just as far down as you can get it.  Take the
male and turn it into the end of the female that the CATV comes
out of. Tighten it down.  With as much of the diaelectric as you
can get into it, cut away the diaelectric.  Slide the UHF barrel
over it, cut it where needed and secure it with the compression
ring and nut.  WX proof as above.

All of the compressions and connectors that I used came from
True Value hardware and about three bucks apiece.  Mine have
been up for a while and do not show any degradation to
performance.

Hope that's clear enough to follow and helps.

    jd


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