Tuning The Transmit Radio Section; Operational Tests; Test Equipment Interconnection To The Repeater - Motorola CDR500 Programming Manual

Tuning the Duplexer and Repeater Operational Tests

Operational Tests

5A. Slightly loosen the locking nuts of the
tuning screws to allow the tuning screws to
turn more freely (but not "sloppy") and
5B. Increase the level of the CSA or the generator
to maintain an audible 1 kHz tone.
6. Repeat Steps 4 through 5B for each of the tun-
ing screws on the duplexer. Begin with the
tuning screw closest to the antenna port and
work in order toward the tuning screw closest
to the receive radio port.
7. Tighten the locking nuts of the tuning screws.
CAUTION
To avoid damage to the tuning screws
and to allow fine tuning of the duplexer,
do not overtighten the locking nuts.
8. Readjust the tuning screws of the duplexer for
the greatest rejection of the signal. This will
fine-tune the receive radio section of the
duplexer.

Tuning the Transmit Radio Section

NOTE
Tuning the transmit radio section of the
duplexer begins with the tuning screw
closest to the antenna port of the
duplexer.
1. Adjust the frequency of the CSA or generator
to that of the receive radio.
2. Place the transmit radio on the receive radio
frequency mode defined in Step 2 under "Pro-
gramming the Radios."
3. Adjust the level of the CSA or generator until
a weak signal is heard from the transmit
radio.
4. Increase the level of the CSA or the generator
by approximately 20 dB.
5. Adjust the tuning screw of the duplexer for
the greatest rejection of the signal. This will
appear as a noisier signal. If necessary:
5A. Slightly loosen the locking nuts of the
tuning screws to allow the tuning screws to
turn more freely (but not "sloppy") and
5B. Increase the level of the CSA or the generator
to maintain an audible 1 kHz tone.
6. Repeat Steps 4 through 5B for each of the tun-
ing screws on the duplexer. Begin with the
tuning screw closest to the antenna port and
move in order toward the tuning screw closest
to the transmit radio port.
5-2
7. Tighten the locking nuts of the tuning screws.
To avoid damage to the tuning screws
and to allow fine tuning of the duplexer,
do not overtighten the locking nuts.
8. Readjust the tuning screws of the duplexer for
the greatest rejection of the signal. This will
fine-tune the transmit radio section of the
duplexer.
If you connected the coaxial cables from
the radios to the 'opposite' ports of the
duplexer, do not forget to reconnect
them to the 'proper ' ports before plac-
ing the repeater into operation.
Operational Tests
Before closing the cover for a CDR500 repeater or reas-
sembling the housing cover to the chassis for a CDR700
repeater, three operational tests should be performed.
A Communications System Analyzer (CSA) with a
duplex generator capable of operating at an offset
equal to the difference between the transmitter and
receiver frequencies (T/R spacing) is the preferred
piece of test equipment. Typical models are the Motor-
ola R2000, R2550, and R2600 Series. Some means is
required to reduce the output of the duplex generator
to the usable sensitivity level. This may be designed
into the CSA or accomplished with an external Step
Attenuator.
These tests assume a properly tuned
duplexer, either internal or external, is
b e i n g u s e d . A n i m p ro p e r l y t u n e d
duplexer may result in serious damage
to one or both radios, the duplexer and/
or the test equipment.
Test Equipment Interconnection to the
Repeater
1. If required, connect the output of the duplex
generator of the CSA to the input of the Step
Attenuator.
2. If required, connect the output of the Step
Attenuator to a coupling tee in line with the
"RF In/Out" of the CSA.
3. Connect the output of the coupling tee, if
required, or the "RF In/Out" of the CSA to the
antenna port of an external duplexer or the
"RX/DPLX" connector for an internal duplexer.
4. If an external duplexer is being used, connect
the "RX/DPLX" and the "TX" connectors at
6864110R66-O
CDR500 & CDR700 Repeater Service Manual
CAUTION
CAUTION
CAUTION
March, 2001