Motorola MTR2000 T5544 Instruction / Field Service Manual page 301

1
DESCRIPTION
The VHF External Double Circulator Module, models CLN1207, CLN1208, CLN1209, provides an additional
45 dB (minimum) of isolation between the Power Amplifier Module and the transmit antenna.
This section provides a general description, option matrix chart, identification of inputs/outputs, and functional
theory of operation. The information provided is sufficient to give service personnel a functional understanding
of the module, allow maintenance and troubleshooting to the module level. (Refer also to the Maintenance and
Troubleshooting section of this manual for detailed troubleshooting procedures for all modules in the station.)
General Description
Note
Motorola Inc., 2005
All Rights Reserved
Printed in U.S.A.
VHF EXTERNAL DOUBLE
CIRCULATOR MODULE
The double circulator assembly consists of two RF circulators (contained
in a single housing, a 50Ω load with heat sink and Low Pass Filter, all
mounted in the peripheral tray. The RF output from the Power Amplifier
module connects to the input of the assembly, while the output connects
to an external low pass filter. The low pass filter provides harmonic sup-
pression for the MTR2000 station. The output of the filter connects to the
transmit antenna (directly, via antenna relay module, or via duplexer).
The double circulator model is typically used in high density radio site ap-
plications where other co-located transmitters near the frequency of the
station can cause intermodulation products. The addition of the double
circulator improves transmitter intermodulation by 45dB.
Government & Enterprise Mobility Solutions
1301 E. Algonquin Road, Schaumburg, IL 60196
Model CLN1207 (132 to 146 MHz)
Model CLN1208 (144 to 160 MHz)
Model CLN1209 (158 to 174 MHz)
68P81096E49-C
09/30/05-UP