[TowerTalk] Homebrewing 7/8" Hardline Connectors?

mpride@us.ibm.com mpride@us.ibm.com
Thu, 16 Dec 1999 16:52:11 -0500

A technique I developed involved essentially dropping the diameter of the
7/8 inch hardline to a point where the standard PL258  (double female UHF
connector) would fit and secure with stainless steel hose clamps.

Starting at the Hardline, clean out the foam dielectric (hollow it out) to
a depth of 1/2 or 3/4 inches.
Slot the outer aluminum jacket (4 equally spaced slots the same length)
Insert a short length of aluminum tubing 3/4 inch outside diameter, 0.058
wall thickness (approximately 1.5 inches long) and slot one end of this
tube to allow for a stainless steel hose clamp.  The end of the tube
without the slots is inserted into the hollowed out area in the 7/8

Before assembly, I have taken a brass screw (or short section of threaded
rod maybe 1/2 inch long without the screw head)  that fits snuggly into the
center contact opening of the 258 connector and solder a short wire (maybe
total length of 1 inch) to it and the center conductor of the 7/8 inch
hardline (taking advantage of the construction of the CATV center conductor
design - copperclad over aluminum wire).  The wire can be easily soldered
to the center conductor of the Hardline.

Using a wire allows some movement of the center conductor of the hardline
(very slight when cable is rolled out or installed).
(my earlier design depended on a pressure contact here and became unstable
after deployment of the cable, so now I solder a wire to the cable to
eliminate any potential disconnection).  There is enough room to insert a
soldering iron or gun into the hollowed out space to make this solder

With this done, insert the wire/brass screw into the 258 connector and
slide the short tube inside the hardline and secure with the first of two
clamps.  Clamping the short 3/4 dia. tube onto the hardline.  Next push the
258 connector into the 3/4 inch. dia. tubing and expose one end (enough
threads to attach a PL259 connector) and secure with the second clamp.

Follow this with sealing compound or silicon sealant, etc. to prevent
moisture penetration.  Make sure the end of the connector (258) is
protected from moisture until you are ready to put the mating connector on
and seal the entire junction with weather sealant.

Been doing this for several years now without any failures to report.

Of course with 3/4 inch hardline, one can fit the PL258 double female
connector directly into the hollowed out portion of cable end and clamp -
no need to drop the outer diameter as with the 7/8 inch hardline.


Mark, K1RX

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