User's Manual

SEL-3031 Instruction Manual Date Code 20091009
Installation
Overview
2.6
➤ When constant interference is present in a particular frequency zone,
it may be necessary to “lock out” that zone from the SEL-3031
hopping pattern. The SEL-3031 includes a SKIP setting that removes
interfered frequency zones from its hopping pattern. See Table 4.5 for
more information on the skip zones and information on how to set the
SKIP setting. In the USA and Canada, a maximum of six zones may
be skipped, per FCC and IC rules. Check the regulatory requirements
for your country.
➤ The RF power output for all SEL-3031 radios in your system should
be set to the lowest level necessary for reliable communications. This
decreases the likelihood of causing unnecessary interference to
nearby systems. See Table 2.2 for more information on the different
frequency zones.
Feedlines
The feedline used with the antenna is as important as the antenna. Coaxial cables
should have low attenuation and rated for outdoor use. Keep the feedline as short as
possible to minimize signal loss between the radio and antenna. Times Microwave
LMR 400
®
or RG-8 A/U coax cables are preferred. If longer lengths or less loss is
desired for the radio link then larger cable such as Andrew HELIAX
®
can be used.
Table 2.3 lists the signal losses (in dB) for the indicated lengths of each cable type at
900 MHz.
Table 2.2 900-MHz Frequency Skip Zones
Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 Zone 8
902.6–
903.8
904.1–
905.3
905.6–
906.8
907.1–
908.3
909.2–
910.4
910.7–
911.9
912.2–
913.4
913.7–
914.9
Zone 9 Zone 10 Zone 11 Zone 12 Zone 13 Zone 14 Zone 15 Zone 16
915.2–
916.4
916.7–
917.9
918.2–
919.4
919.7–
920.9
921.2–
923.0
923.3–
924.5
924.8-
926.0
926.3-
927.5
Table 2.3 Length vs. Loss in Coaxial Cables at 900 MHz (Sheet 1 of 2)
Cable Type
3.05 Meters
(10 Feet)
12.24 Meters
(50 Feet)
30.48 Meters
(100 Feet)
91.44 Meters
(300 Feet)
RG-8 A/U
(C964)
0.70 dB 3.50 dB 7.0 dB Unacceptable
Loss
LMR 400
(C966)
Do not use 1.95 dB 3.90 dB Unacceptable
Loss
1/2-inch
HELIAX
Do not use 1.15 dB 2.29 dB 6.87 dB