Cavity And Duplexer Tuning Bandpass Adjustment - Motorola R-2200 Operator's Manual

6. To check the transmitter's distortion, connect the
service monitor's "Demod Out" to the "Vert/
SINAD/Dist" input jack. Set left LCD to "Dist''
and read OJo distortion on the display.
If using an R-2400, the "Pwr Mon/ Anlzr On" function
may be used alternatively, to observe both the modula-
tion, recovered demod and frequency spectrum signals.
0
Ywt/SII.N>/
Rf
In/Out
1>151/DIIM
Ext Horiz Domocl Out Mod Out Ext Mod In
0 0 0 0 0
FIGURE 5.11-DUPLEXER PASSBAND
ADJUSTMENT SETUP
5.14.0 CAVITY AND DUPLEXER TUNING
BANDPASS ADJUSTMENT
A. Passband Adjustment
1. Connect the service monitor's "RF In/Out" to the
in-service duplexer antenna port as shown in
figure 5 .11.
2. Set left LCD to "Dev", "Function" switch to
"Gen", "FM", and modulation switch to "Off'
position.
3. Enter the receiver frequency.
4. Set the RF Step attenuator to -30 dB and the "RF
Vernier" to mid-range, to allow adequate signal
to get through a mistuned duplexer and quiet the
receiver. Reduce the signal generator output, as
necessary, to keep the receiver limiter meter read-
ing below saturation. Use "Hi Gen" and the "An-
tenna" port if the duplexer is badly mis-tuned, to
start.
5-8
5. Tune the pass-band knobs of the cavities in the
duplexer receive leg, for a peak reading on there-
ceiver limiter meter. Reduce the signal generator
output, as necessary, to keep the receiver limiter
meter reading below saturation. This completes
the pass-band adjustment for the receiver leg.
6. Set the "Function" switch to "Pow Mon" (or
"Pwr Mon/ Anlzr On") and the attenuator to
-30 dB. For low-power transmitters, it may be
necessary to reduce the attenuator setting to un-
squelch the monitor. Too high an attenuator set-
ting or too tight a squelch setting will inhibit the
display of frequency and deviation information.
7. Enter the transmitter frequency. Key the trans-
mitter and tune the pass-band knobs of the
cavities in the duplexer transmit leg for maxi-
mum power output. This completes pass-band
adjustments.
D ~~~
O.v~Pwr~
-
0
Rf
In/Out
~'='
Ext Horir Oomod
011
0 0 0
:10 1111 PO\IER LOAD
Mod 011 Ext Mod In
0 0
FIGURE 5.12-DUPLEXER ADJUSTMENT SETUP;
REJECT NOTCH ON RECEIVE LEG
5.15.0 CAVITY AND DUPLEXER TUNING
BANDPASS WITH REJECT NOTCH
B. Adjustment of Reject notch on the Receive leg.
1. Connect the service monitor's "RF In/Out" to the
in-service duplexer as shown in figure 5.12.
Disconnect the cable at the duplexer receiver port
that comes from the receiver. Move the monitor's
"RF In/Out" cable from the duplexer antenna
port to the duplexer receiver port. Connect a
power-rated dummy load to the duplexer anten-
na port.