This instructable shows you how to make up coaxial cables to your specific
lengths by using *clamp type* Type-N connectors at the ends of your
cables, which requires using only simple tools. This procedure is specific
to LMR400 or Belden 9913 ultra low-loss cable types, but these techniques
may be useful for other cable types for which clamp type connectors are
This ultra low-loss cable and connector combo (LMR400/Type-N) is widely
used in cell phone booster (repeater) systems, ham radio antennas, as
well as other transmitting/receiving application. It is especially
recommended for cell booster systems in fringe reception areas with weak signal strength, where signal loss in the cable really matters.
In general, coaxial connectors may be installed on cables either by
crimping them on (using special crimping tools), or for some special
connector types, connectors are available that can be clamped on using
only simple tools. The name clamp for this connector style may be
misleading. In the plumbing or automotive trades, with this method of
attachment to the cable, it would probably be called a "compression
This instructable deals with the clamp type connectors only, but for an
informative video on how factory crimp Type N connectors are installed,
click on the link below:
LMR400 (or Belden 9913) cable is available from several sources online,
and is available by-the-foot or in pre-made lengths with connectors
installed at the ends. Wilson400 cable is Wilson's "house brand" of the
LMR400, and is sold on Amazon.com.
So, you have a choice of making up your own cables to exact lengths for
your system, or you can buy them pre-made. Ready made cables would
have to be purchased longer than needed (with the excess tucked away)
in most cases, unless the system could be designed around available
lengths. I chose to buy one longer roll (with two of the needed connectors
already installed) and I made my individual cables from that roll.
Here are some prices of pre-made cables
on Amazon.com as of Feb., 2012.
2-Foot cable $ 9.95
10-Foot " 27.95
20-Foot " 37.27
30-Foot " 41.99
50-Foot " 54.51
100-Foot " 90.24
If you're installing a cell phone repeater system, you may need several connectors. At a minimum, you'll need two cables (four connectors) -
one cable from the outside antenna to the booster, and one cable from
the booster to the inside antenna. Wilson Electronics also strongly
recommends installing surge protection in the line, as well,making three
cables (six connectors).
If your system includes lightning surge protection, splitters, and multiple
inside antennas, the connector count can go higher. The diagram above
shows possible connector locations, labeled "C."
Connectors and adapters of all types are available from Dave Fant in
Mulberry, Arkansas, an ebay seller. He has terrific prices, fast order
processing, and reasonable shipping.
Here is the link to the clamp Type-N connectors at Dave's Shop:
Or, you can browse Dave's website. He has the connectors listed as:
$3.99 each. Shipping, $3.25 for first item, $.50 each additional.
Prices, Feb., 2012.
The solder required to attach the male contact (center pin) is .022"
It's available from Radio Shack, part #64-013. $6.99, Feb., 2012.
>>>Heat Shrink Tubing
Seal the back of the connector from moisture with this. Recommended
for connections exposed to weather, optional for indoor locations.
A 2" long section of 3/4" tubing works perfectly for each connector.
Available from Harbor Freight Tools in an assortment that contains five
different sizes of tubing, including 4 feet of 3/4" size tube.
Item # 09639, price $3.99, Feb., 2012.
Razor blade or tool to cut cable jacket
Comb or tool to rake shield wires
Scissors to cut shield wires
Soldering gun or soldering iron to attach the male contact
Vice or clamp to hold cable while soldering
Propane torch or heat gun for heat shrink tubing
left to right:
male contact (center pin) - body - clamp - gasket - washer - nut
shrink tubing, the nut, the washer and the gasket over the end of the
The groove in the gasket faces the cable end.
around the cable about 3/8 to 1/2 inch from the end. A single-edge
razor blade is a good tool for this job.
Remove the piece of the jacket, exposing the braided shield.
Rake out the braid. A fine-tooth comb works well for this.
Then, stand the wires up perpendicular to the cable....
....and trim the wires to 3/16". Ordinary scissors work fine.
the shield wires back over the jacket. Check that no wires protrude
from the rear.
without nicking the center conductor.
Make this cut to leave 1/8" of the insulator protruding past the end of the
jacket, as shown in the pictures above and below.
Remove the cut piece of the foil-wrapped insulator.
Check to be sure this is a clean cut, with no part of the foil shield able to touch the center conductor.
The center conductor of this coaxial cable is a copper-clad aluminum
wire and is very soft. Making the cut of the center conductor wire
with dull cutters may smash this wire out-of-round, making it difficult
to slip the male contact over it. The hole in the center pin/male contact
is barely larger than the center conductor that goes into it, so cut the
conductor carefully to avoid deforming it. It may be necessary to dress
the cut end of the conductor until the male contact will slip over it easily.
.022" diameter solder.
of heat. The large copper coated aluminum center conductor wire
is a good heat sink, and sucks the heat away from your work almost
as quickly as you apply it. A 325 watt soldering gun isn't too much.
A 30 watt electronics soldering iron won't do the job.
holding device with the solder hole facing *up*. Hold the solder
vertically into the solder hole as you apply the heat to the *bottom*
of the male contact.
After soldering the male contact, assemble the connector by
slipping on the clamp and screwing the nut into the connector body.
connector compresses the clamp, providing strain relief for the
cable, and tightening expands the gasket, waterproofing the
internal electrical connection.
Slide the heat shrink tubing up onto the connector.
and the connector.
You now have a functioning connection at the end of your coaxial cable. When
this connector is screwed together with the fitting at the device, it will be
secure, waterproof, and electrically sound.