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The outer jacket for mainline cable
is aluminum, while for household cable, the outer
conductor is a braided copper jacket. All varieties
of coax cable have a copper inner conductor. aluminum
outer jacket, a foam inner core, Because of this,
coaxial cable is subject to changing size with temperature
changes.
Cables are all plastic coated,
and some come with a gel water barrier, or an absorbant
material liner. Depending upon the type of installation
and the location, the cable supplier will be able
to recommend the appropriate type of cable.
Generally speaking, water-resistant
or water-proof cables are more expensive, more difficult
to work with, however they are more durable against
the environment.
Coaxial cable comes in various
sizes up to 1" diametre, stepped at 1/8"
intervals. (.500 = 1/2", .625= 5/8", .750=3/4"
etc.) Larger diameter cable also has a larger centre
core. This makes larger diametre cable more difficult
to work with, however the signal will travel further
down a larger cable, meaning that less in-line amplification
will be required, which will cost less. (Installing
fewer amplifiers will cost less money).
Large diametre cable is generally
used for main trunk distribution lines, while smaller
cables are easier to work with and are more often
used in the bridge distribution portion of the cable
plant. Additionally, because there is usually more
equipment installed in the bridge portion of the cable
plant (taps, splitters, amps), more signal will be
lost in this portion of the system. Because of the
additional signal loss, there is not much benefit
to using a larger diametre cable.
Make
sure the end is a clean cut before beginning:
Before installing a connector, ensure that the
coax cable end is still round. To do this, it
is sometimes easiest to make a fresh cut on
the cable that you are going to use.
- Using cable cutters, cut through the outer
portion of the cable by circling the cable
with the cutters a couple of times. This will
mar the aluminum outer jacket, and help to
weaken it. This will help to keep the cable
shape round once it's cut.
- Once the cable is prepared in this way,
and the end still looks round, three to four
inches of aluminum jacket will need to be
exposed in preparation for installing the
connector. Three to
four inches exposure should be ample room
for connectorization, no matter what size
cable is being prepared.
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Cut
the outer jacket: Using
a knife or cable cutters, cut around the cable
about four inches up from the end, cutting through
the outer jacket. Then, using a knife, cut into
the cable jacket in a line parallel to the cable
length, from the end of the cable to the cut
that you have made.
Be careful to ensure that
in doing this, it is mostly only the outer jacket
that is being cut. As
much as possible of the protective aluminum
coating needs to be preserved. |
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Remove
the outer jacket: If
the outside jacket was properly cut using the
instructions above, it should easily slide off
if the coax is non-waterproofed cable.
If the cable is waterproofed,
solvents will have to be applied using rags,
and the jacket may be more difficult to slide
off. The waterproofing solution generally makes
the cable jacket stick very well to the cable.
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Make
sure that the aluminum jacket is clean:
If the cable that you have purchased has a water-proof
gel or coating, it will need to be cleaned with
the solvent recommended by the cable manufacturer
or supplier. |
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Centre
core: The end
of the cable being worked with should now appear
round, and the centre (still round) core should
be visible, as shown.
If it is as shown, then the
cable is ready to core, which will expose the
centre conductor and remove enough of the white
foam medium to allow the connector to be installed.
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Line
up the coring tool and cable: The main
idea behind coring is to get the centre of the
cable into the centre of the coring tool, so that
the cable will turn out as required. This
job takes practice. |
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Insert
the cable into the centre of the coring tool
carefully: Ensure
that the cable is still lined up on centre with
the coring tool. |
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TIP:
If you are having trouble seeing where the
centre is on the flush end of the
cable, use a knife or cutters to remove
the outer aluminum jacket and foam
to expose the centre conductor at
the end of the cable. This will allow you
to see the centre pin clearly and
be able to insert it into the centre of
the coring tool. |
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Begin
coring: The length
of the copper conductor that needs to be exposed
will depend on the type of connector being used.
Read the specifications provided
with the connector to ensure that the correct
amount is exposed, or look on the connector
itself, as this dimension is sometimes printed
right on the connector.
Install the correct diametre
of coring tool onto the drill, and begin to
core. |
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Clean
any plastic coating off the copper conductor:
There will usually
be some plastic residue remaining once the coring
is completed to expose the copper conductor.
Because this coating is
sometimes clear, it may look like copper wire
until it is scratched at with a thumbnail, or
other suitable tool. (A thumbnail is suggested
because it won't harm the conductor)
Ensure that as little damage
as possible (no nicks or scratches) is done
to the copper conductor) Avoid
knife marks!!! These will weaken the conductor. |
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Or,
use a stripper to clean the end: It is
also possible to use a stripper to make sure that
the end of the copper conductor is cleaned, however,
as mentioned above, make sure that the centre
conductor is not damaged in the process. |
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Cut the end to
length, according to the specifications: The
connector manufacture will specify exactly how
long the centre conductor needs to be. Measure
accurately and use cutters to trim the end off
squarely. |
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Ready
for connector? check the specifications and instructions
for the type of connector you have! The
cleaned, cut to length squared off end is now
ready for the connector. There are many different
kinds of connectors, however most contact the
cable in a similar fashion. Make sure that you
have the correct specifications and instructions
for the type of connector you are using, before
continuing with connectorization. |
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If
the connector is going onto an existing
outdoor line, NOW is the time to slip the
heat-shrink tube over the end of the line,
BEFORE the connector is in place.
(If you don't put the heat shrink on first,
it means that you'll have to undo the connector
again to slip the heat shrink over, then
begin the tightening process again.) |
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The
connector portions are tightened using wrenches.
Connectors will all contain water-tight seals,
however conductors installed outdoors will need
an additional heat-shrink tube installed once
the connector is in place. This will help stop
corrosion and will extend the lifespan of the
connector.
Connectors provide a terminating
centre pin (shown at the left), which use the
copper to connect the cable. Different lengths
of connector pins are available, however, for
maximum flexibility, purchase the longest lengths,
and trim as necessary. |
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following sequence of photographs shows the correct
order for installation of a connector. |
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Connectors are
first hand-tightened onto the coaxial cable, then
are tightened with wrenches as each additional
connector section is added on. |
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Wrenches of two
different sizes are turned in opposite directions
to fasten on the connectors. Most often the pin
part of the connector is fastened to the equipment,
before the back two portions of the connector
are screwed on and the cable inserted to complete
the connection. |
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The completed
connector after tightening. |
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connectorization makes it possible to join virtually
any piece of equipment or cable together. The
photographs below show the sequence used in joining
two pieces of coaxial cable together via a splice. |
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This shows all
of the completed portions of a splice broken apart. |
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This shows the
splice with both ends completed and ready for
insertion into a splice block. |
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The completed
splice. |
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When a connector
is used "in the field," it is generally
shrink-wrapped as shown, to seal it off from the
elements. In this case, the shrink-wrapped connector
is shown installed on a service feed tap, off
of a bridger line. |
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A
heat-gun is used to shring the heat-shrink tubing
over top of the connector to seal it and protect
it from the elements.
If no power is available,
a torch will work to shrink the heat-shrink
tubing. Some diffuser ends for torches will
work better than others. If using a torch instead
of a heat gun, take care NOT TO BURN the heat-shrink
tubing. Burned heat shrink won't protect the
splice. |
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Connectors are
used to connect coaxial cable to inline devices
such as service taps. The same principle applies:
connectors are first hand tightened-on, then finish-tightened
with a wrench. Again, the pin portion of the connector
should be mated to the inline device first and
tightened.Then the mainline and rest of the connector
are applied as follows. |
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All connectors
are then able to screw into the housings on equipment
that is mounted on the cable lines. The housings
on the equipment help to complete the connection
by forming a circuit with the outer aluminum jacket.
Inside, the centre pin is secured into the equipment,
and screwed in with a pin screw to complete the
centre copper connection. |
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Connectors in
the field must be properly cleaned in order to
work properly. They must then be carefully sealed.
A downward slope or "drip loop" is important
following a connector to ensure that water runs
away from the connector and equipment. This driploop
would be made in the mainline cable, immediately
after the connector. |
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If long pin connectors
are purchased, they can then be cut to the correct
length to accommodate the specifications for any
device. Different types of devices have different
specifications for pin length. |
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The
connector pin at left has been cut to the correct
length for this device. |
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TIP:
If when purchasing connectors you are unsure
about what kind to purchase, purchase connectors
with LONGER pins. This will provide more
flexibility to be able to accommodate more
types of equipment. |
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Insert
the cable end into the correct diametre of coaxial
strippers.
There is usually a stopper
which will help to guage the correct length
of coaxial jacket to strip. If the stripper
being used does not have a stop, expose 3/8"
of the copper centre. The amount of copper shield
exposed will then be dictated by the strippers.
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Spin the strippers
around the cable. A good method for this is to
go two times around the cable in one direction,
and two times around in the other direction. This
will cut through the outer jacket and also help
to prevent the outer shield from wrapping around
the copper core. If the outer shield does come
into contact with the core, it will ground out
the connector. A grounded out connector will not
work. |
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Hold onto the
cable firmly with the strippers, and pull away
from the cable, holding the cable firmly in the
opposite hand. The tip of the jacket will come
away. |
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The strippers
will expose the centre conductor, will cut through
the outer jacket, and will expose the outer woven
conductor. |
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Push
the woven conductor back, splaying it out so
that when the connector is pushed over the cable,
it will make a good connection.
Also, check to make
sure that no outer conductive material is making
contact with the centre pin. |
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Push
the correct diametre of connector on, as far
as it will go. the connector will stop once
it has been pushed on fully. This generally
means that the connector floor is flush with
the end of the foam centre where the pin protrudes.
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Insert the connector
and cable into the crimper tool. Make sure that
it is lined up properly, and crimp the connector
on VERY firmly. |
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The
completed connector should be very firmly attached
to the cable, and is ready to use. These types
of connectors are used for interior connections.
Connectors should be tested
immediately after installation, using a connector
test meter. Generally the only problem that
may arise with a connector is that the outer
braided conductor is making contact with or
is too close to the centre conductor, which
would cause the connector to malfunction.
Unlike networking cables
however, coaxial connectors work a very large
percentage of the time. |
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