Motorola CDR500, Programming Manual

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1-4
6864110R66-O March, 2001
Introduction to Repeaters and Components CDR500 & CDR700 Repeater Service Manual
Duplexers, Cables, and Antenna Spacing
accessories with each repeater controller. Table 1-4
shows general compatibility for the other accessories
available with the CDR500 and CDR700 repeaters.
Additional accessories may be compatible if custom
programming is done on the CPS and/or accessory
cables are modified.
Duplexers, Cables, and Antenna
Spacing
Duplexers
The duplexer “isolates” the receive radio from the
transmit radio in the CDR500 or CDR700 repeater.
Without this isolation, the ability of the receive radio to
detect weak signals would be severely degraded by the
output signal of the transmit radio. Isolation may also
be obtained by using separate antennas with proper
spacing (distance) between the antennas. Less vertical
spacing is needed for a given isolation of land mobile
antennas than may be obtained easily with horizontal
spacing.
There are two basic types of duplexers:
• bandpass
• bandreject
The bandpass duplexer has two filters connected
together such that each filter will “pass” or appear
transparent to, a narrow segment of frequencies; the fil-
ters are tuned to different frequencies. Any signal
within the segment is transferred from or to the
antenna while frequencies outside of the segment are
“blocked.”
The bandreject duplexer has two filters connected
together such that each filter rejects, or “blocks,” a
narrow segment of frequencies. Again, the filters are
tuned to different frequencies but any signal outside of
the segment is transferred from or to the antenna
while frequencies within the segment are “blocked.”
The choice of which duplexer configuration to pur-
chase may be dictated by the particular application. If
several repeaters and a CDR500 or CDR700 repeater
are to operate at a given location, the bandpass
duplexer might provide additional rejection to the sig-
nals from the other radios.
Basic Specifications
The basic specifications for a VHF or a UHF duplexer are:
• Impedance: 50 ohms
• Isolation: 70 dB minimum
Instead of the term “isolation,” the manufacturer of
the duplexer may use the terms “Receiver (or Rx)
Isolation at the Transmitter Frequency” and “Trans-
mitter (or Tx) Noise Suppression at the Receiver Fre-
quency.”
• Power handling: 50 Watts minimum
Power handling may be called “Continuous Power
Input” by the manufacturer. If a Lowband repeater
is being assembled with the low band Professional
Table 1-3. Accessory Compatibility (Audio & DTMF)
Repeater Controller
Part No. Accessory
SmaT
runk
Zetron 42 Zetron 49 T
rident
RAIDER T
rident
Marauder i20R Basic ZR310 ZR340
X X X X L3144, L3147 Local Desksets
X X X X L3150 DC Remote Adapter
X X X X L3151 Tone Remote Adapter
X X X X X X X X X HMN3000_ Desk Microphone
X X X X X X X X X AARMN4026, 4038 Enhanced Keypad and Heavy Duty
Microphones
X X X X X X X X X AAREX4617 Telephone Style Handset
Table 1-4. Accessory Compatibility (General)
CDR500
Repeater
CDR700
Repeater Part No. Accessory
X X HSN8145 7.5 Watt External Speaker
X X RSN4001 13 Watt External Speaker
X HLN9169 CDR500 Wall & 19” Panel Mount
X HLN9455 CDR700 Battery Revert/Float Maintenance Charger