Bird Technologies 28-69-04A - Manual (Page 6)

UNPACKING
Care should be used when removing the duplexer
from it's shipping container to avoid unnecessary
damage. It is important to visually inspect the du-
plexer for any shipping damages as soon as pos-
sible after taking delivery.
It is the customers
responsibility to file any necessary damage claims
with the carrier.
Vari-Notch duplexers are rugged devices but may
become detuned if jostled or dented during ship-
ping. The most easily damaged parts of the du-
plexer are the tuning rods. These rods are marked
where they exit from the locking nut with a dab of
red varnish or other color/type of paint. If this seal
appears to be broken it may indicate that the sys-
tem has been detuned in transit.
INSTALLATION
Vari-Notch duplexers should be securely installed
in a dry, vibration-free environment. Attachment of
the cavity shells to a grounding bus is recom-
mended in order to maximize lightning protection.
A lightning protection device placed in the antenna
feedline, preceding the duplexer, is also recom-
mended. High quality double shielded coaxial ca-
ble terminated with quality connectors (N-type) are
recommended for connecting the transmitter and
receiver to the duplexer, and are available from
TX RX Systems Inc. It is also important to observe
the power handling ratings of cables in transmit
systems.
Mount the duplexer in it's permanent operating po-
sition using suitable hardware. Connect the two
transmitters (or transmitter/receiver) and the an-
tenna feedline to the duplexer making sure to con-
nect the correct equipment to the correct port.
Labels are affixed next to each port (port labels) to
help you make the right connections. In addition, a
specification tag will be found in a plastic bag at-
tached to one of the tuning rods. The frequency
that each cavity group is tuned to will appear on
either the port labels or the specification tag. The
duplexer is now ready for normal operation. No
tuning is required if the frequencies (high fre-
quency and low frequency) found on the port
labels/specification tag matches the actual operat-
ing frequencies.
MAINTENANCE
No special maintenance is required. Vari-Notch
duplexers are passive devices of rugged electrical
and mechanical design. They are tuned at the fac-
tory for the original design requirements and re-
quire no further adjustment or maintenance.
These devices will stay properly tuned unless they
have been physically damaged or are tampered
with. Check for loose or corroded connectors on
TX RX Systems Inc. Manual 7-9177-1 09/19/97 Page 2
High
Frequency
Equipment
RG214 or RG142
Double-Shielded Cable
(Supplied by customer)
To
Antenna
TYPICAL FOUR CAVITY VARI-NOTCH FILTER
Interconnect Cable
(1/4
λ
or 3/4
λ
of this)
(channels pass freq.)
Antenna Cable
(1/2
λ
of the other)
(channels pass freq.)
Vari-
Notch
Filter
Vari-
Notch
Filter
Vari-
Notch
Filter
Vari-
Notch
Filter
Low
Frequency
Equipment
Antenna
Junction
Passband tuned to high frequency
Rejection notch tuned to low frequency
Passband tuned to low frequency
Rejection notch tuned to high frequency
Figure 1: Block diagram of a typical four-cavity Vari-Notch Duplexer (6.625" diameter cavities).