|Planet Fox > Microwaves
There are few things people make a bigger mess of than
especially builders. When I was installing satellite TV I spent a large
portion of my time correcting other people's cabling mistakes. It is the most common cause of failure
in satellite TV systems. It saves everyone a lot of time and money if
it's done right the first time, here's how.
- Never use anything other than a coaxial cable
cable, they're cheap easy to use and always strip the right amount of
insulation without damaging the cable. I've seen people use wire
cutters, scissors, wire strippers, even box cutters. Please do not do
this, in the best case scenario you will have poor performace, in the
worst case scenario you may actually damage equipment by shorting the
shield to the center conductor.
- Do not staple coaxial cable, ever. Only use actual
Staples penetrating the insulation are the second most common cause of
shorts, and the pressure from the staple gun deforms the cable's
dielectric, decreasing performance.
- Never fasten cables inside walls, or in any other
There's a good chance the cable will need to be upgraded or replaced at
some point, and it's much easier when you can just tie the new to the
old and use it
to pull the new cable.
- Do not buy RG-59 cable. This only works for
and cable TV, and it's not even very good at that. Use good quality RG6.
In general you'll want to buy the highest quality cable,
within reason. If it has any common electronics manufacturer's name on
it (Philips, Magnavox, etc) then it's probably crap. The standard grade
of cable these days is RG-6, with a 60% aluminum braid and 100%
aluminum foil shield, and will be rated to carry signals up to 3000
MHz. The center conductor may be made of copper plated steel or solid
copper, depending on the application. The older RG-59 type of cable
should never be used for new installations, since it's unable to carry
signals above 900 MHz, making it useless for today's high bandwidth
The higher the frequency, the greater the losses in any
cable will be. For extremely long runs, such as over 100 meters for
1450 MHz or over 40 meters for 2150 MHz you may have to invest in RG-11
grade cabling. For any application where the cable is responsible for
carrying voltage to remote equipment (LNBs, switches, preamps) the
total cabling run shouldn't exceed 40 meters when using a cable with a
steel center conductor. High current equipment like the
block-upconverters on satellite internet antennas should only be
installed with solid copper cable.
The top brands that you'll want to look for are
Commscope "Bright Wire", Belden, PCT/Channel Master, and Eagle Aspen,
in that order. Please do not waste money buying gimmicky cables with
weird dielectrics and extra braids and stuff, none of that really helps
and sometimes, as is the case with "quad shielded" cabling, actually decreases a cable's performance.
Stripping the Cable
When stripping a cable it is essential to expose the
each layer, and to do so without damaging the cable. There is a very
specific tool meant to do exactly this and I strongly suggest you use
it. The best device I've found is the Paladin
Tools Data Shark, which
costs less than $10 and has a notched blade to avoid cutting into the
center conductor. All connectors are designed to be inserted onto a
cable which has had ½" of the outer jacket and ¼"
of the dielectric stripped. It's important to cut the dielectric
evenly, and without crushing it. Fold the braid wires back and make
sure none of them are touching the center conductor.
cable on the left was stripped with a Data Shark, the one on the left
looks to have been stripped with a wirecutter.
There are a wide
variety of connectors available, but
two which are currently in wide use on a professional level -
compression and hex crimp. Both require a specific tool to be used
properly, which costs around $20-$50. Hex crimp connectors are
inexpensive and durable, but are not meant to be used outdoors. My very
brand of hex crimp connectors are Steren, due to their tarnish
resistance and ease of use. Compression connectors are more elaborate,
featuring an annular sleeve that locks the cable in place and forms a
weathertight seal. Compression connectors are supposed to offer less
than hex crimps at high frequencies, but I've been unable to measure
any significant difference in signal quality at up to 2150 MHz.
is very bad practice. The dielectric is chewed up, the center conductor
is not long enough on the top one, and too long on the bottom one. The
braids should never stick out past the connector, and although it's not
visible in this picture, the bottom connection is shorted because a
braid is wrapped around the center conductor.
image shows proper connector installation. The dielectric is flush with
the inside of the connector, the connector is compressed fully and
evenly around the cable, and there are no braids visible. The center
conductor should protrude out of the connector by about the thickness
of a nickel.
All outdoor connections should be compression type
should be torqued to 22 in-lb with a torque wrench. Don't exceed 22
in-lb, since you can destroy equipment by overtightening. The actually
make a tool
specifically for this. Try to find
compression connectors that don't have exposed plastic
parts. For example, I've seen Thomas & Betts, PPC, and Digicon
connectors fail when their plastic sleeves cracked due to sun damage.
The best ones I've found are the PCT
one piece nickel plated brass compression connectors, which have an
and even includes a little washer to help seal up the inside of the
connector. For extra insurance, you can fill outdoor connectors with silicone
Outdoor connections should never be made with the cable
downward toward the connector. Water tends to drip down the cable, and
can enter the cable much more easily that way. When possible, make
connections with the cable hanging below the connector. Devices like
switches and grounding blocks with connectors on opposite sides are
meant to be installed horizontally, and with the cable angled downward
and away. Down-coming cables should have 4" drip loops before entering
a structure or being terminated with a connector.
For the most part, rubber boots, washers, etc are
when the connectors are properly installed and torqued. I do, however
recommend capping any exposed ports on outdoor switches, splitters, and