Bird Technologies 21-87A-11-xx-T Series-Manual - Manual (Page 13)

TX RX Systems Inc. Manual 7-9100-5 10/17/11 Page 7
6) Similarly connect the T-Pass Thruline cables to
the cavities using the THRULINE DATA Sheet
and figure 3 as a guide.
Caution: The Thruline cables must
be installed in the correct location for
proper operation. Use pliers with rub-
ber jaws to tighten these connections
slightly more than finger tight.
This completes the assembly of the basic multicou-
plers. Any accessories should be mounted to the
rack using the supplied mounting hardware and
adapter plates.
Installation
The multicoupler should be located in a dry and
level area, indoors. It is best if all transmitters are
as equal in distance as possible from the combin-
ers so that cable losses are the same for all chan-
nels. Figure 5 shows a suggested orientation for
the equipment. Two points are important. First, a
work area space should be left as illustrated so that
the tuning controls are easy to access. This will
facilitate tuning when channel frequencies are
changed. Secondly, space is needed when adding
expansion channels. If there is a lack of space to
access the side of the combiner, then plan to allow
the rack to be moved into the indicated work area
to facilitate adding channels. This will require some
slack in the cables that connect to the station trans-
mitters.
Four, 17/64" (6mm) diameter mounting holes are
provided in the base for attaching the rack to the
floor using bolts or lag screws.
Each transmitter connects to its respective channel
through an ‘N-style’ female connector on the isola-
tor. We recommend using a high quality double
shield or semi-flexible cable for this purpose. Rigid
cable may be used but extreme care is needed to
prevent damage to the connector on the multicou-
pler. High quality connectors should be used for all
connections to the multicoupler. Connectors with
gold plated center pins are preferred to minimize
the generation of intermodulation distortion prod-
ucts.
The antenna connection is made to a female N
connector on the last T-Pass cavity in the chain
near the top of the rack. A flexible jumper of high
quality coax is convenient for this purpose. This
jumper should be rated to handle the total power
output of all the transmitters combined. Since most
transmitter multicouplers exhibit an average 3 dB
loss, the actual total power output will be approxi-
mately 1/2 the total transmitter power. However,
we recommend cable rated at twice the actual
required power as a safety factor.
Direct connection to the hard line antenna cable is
also possible but care should be exercised to pre-
vent damage to the cavity connector due to exces-
sive bending force created by misalignment of the
hard line.
Radio
Cabinet
Radio
Cabinet
Radio
Cabinet
Radio
Cabinet
Work
Area
T-Pass
Transmitter
Combiner
Figure 5: The multicoupler should be positioned so that there is access for tuning and servicing.