User's Manual

Page 7 of 11 6/17/2003
Antennas and Amplifier Use
Bi Directional Amplifier
A Bi-Directional Amplifier may be needed if an application requires long lengths of coaxial cable to reach
the antenna. The amplifier is designed to put maximum transmit power right at the antenna and boost the
received signal primarily to overcome the cable loss. Only the RF Linx 2400LX-0.5W approved amplifier
may be used.
Note: The RF Linx 2400LX-0.5W shall be marketed only in the system configuration with which the
amplifier is authorized and shall not be marketed as a separate product.
The amplifier is designed to operate with a coax cable loss between the radio and amplifier of 6.5dB to
20dB. Within this range, the output of the amplifier is always 1/2W regardless of the input level. The
amplifier may not be used with a cable loss of less than 6.5dB. The use of a cable less than 6.5dB will
result in violation of 47 CFR Part 15 Rules under which the equipment has been authorized. With more
than 20dB cable loss the amplifier will not turn on.
See the chart below for the minimum and maximum lengths of various cable types required when the Bi-
directional amp is used.
Proper installation of the amplifier and its power supply is shown below. The DC injector should be
located by the radio, and the amplifier should be at the antenna. The Bi-directional amp is weather proof
and can be mounted outdoors. See Bi-Directional amplifier instructions for more details.
Antenna Cable Type and lengths
Cable Type
Cable loss/100'
(dB)
Minimum
length (ft)
Loss
(dB)
Maximum
length (ft)
Loss
(dB)
LMR195 18.2 36 6.5 109 20
LMR400 6.9 94 6.5 289 20
LMR600 4.4 148 6.5 454 20
LDF4-50A 3.9 167 6.5 512 20
LDF5-50A 2 325 6.5 1000 20
DC power supply
Locus
OS2400HSE
Power amp DC
injector
RF BI-Directional
Amp
See chart for
minimum/maximum
cable lengths