Diplexers
A diplexer is a device that allows one coaxial cable to carry BOTH your
satellite signal and the signal from your off-air antenna. At first, this may seem like a
great deal, especially if you're faced with the prospect of running more wires through a
difficult area of your house. Unfortunately diplexers are just like splitters; in that
each time you use one, you cut your signal in half. And diplexers have to be used in
pairs! One diplexer combines the two signals together, and the other one splits them back
apart again.
I prefer to run wire whenever possible. Coax cable is reliable, relatively easy to
troubleshoot, and you can run an awful lot of it for the price of two diplexers. But
sometimes it seems like you just don't have any choice in the matter and you're stuck
using diplexers.
Types of Diplexers
Diplexers are similar to splitters in appearance and come in three basic types:
Single port power passing for use when DC power should flow through only one leg. The manufacturers of these indicate the legs that power flows through by drawing a line connecting the two power passive ports on the face of the diplexer.
Dual port power passing for use when DC power should flow through all legs. The only time you should use a pair of these is when you need to power your off-air antenna from your satellite receiver.
The third type of diplexer is built into a Multiswitch and is of the non-power passive variety.
Care must be taken to choose the correct diplexer for your application and to install it correctly. The last thing you want to do is apply power to a device (such as your TV or VCR) that wasn't meant to be powered.
Choosing Diplexers
Again, the only time you're going to use a diplexer is when you need to make one wire do the job of two: In this case carry both satellite and off-air antenna signals.
If your off-air antenna is not powered, purchase single port power passive diplexers.
If your off-air antenna is powered, but the wire you're trying to make do double-duty isn't between the antenna and the power supply, again purchase single port power passive diplexers.
If your off-air antenna is powered, located next to your satellite dish, and you want to use one wire to carry the signals from the outside all the way to your satellite receiver, you'll need one dual port power passive diplexer and one single port.
Installing Diplexers
Using Single Port Power Passive Diplexers
Notes: Both diplexers have a line connecting
one port on the output side of the diplexer and the input side. This shows that power is
passed only between those two ports. It is important to install the
diplexers as shown so the voltage can travel all the way to the satellite antenna. |
Using Diplexers with a Multiswitch
This configuration is for use when you want to power three or more satellite receivers from one dual-feed satellite dish. The multiswitch has a built-in diplexer .
Notes: The diplexers have a line
connecting one port on the output side of the diplexer and the input side. This shows that
power is passed only between those two ports. It
is important to install the diplexers as
shown so the voltage can travel to the multiswitch. |
Using Dual Port Power Passive Diplexers
The only time you would want to do this is if you can't run another wire
from inside the house to the outside.
Notes: In the illustration the outside
diplexer has a line connecting the input side to both outputs. This shows that power is
passed to both ports. |