Codan Radio MT-4E Analog and P25 Digital - Maintenance Guide - Manual (Page 34)

MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Chapter 5: Codan Radio System Testing Page 26
Audio Level:
The audio level adjustment is not required when connecting the receiver in a repeater confi guration
using LVDS Serial Data. The audio level adjustment can be done on both the Rx Balanced Audio
Output and the Auxiliary Balanced Output (1 and 2). The Auxiliary Balanced Output is only available on
the AC-3E Control Card or CI-BC-4E Base Control Card.
To adjust the receiver balanced audio output, ensure that the AC-3E Control Card or CI-BC-4E Base
Control Card is NOT plugged into the subrack, disconnect the Rx Balanced audio output from the Audio
Input of the IFR 2975 (audio box) and connect it to the DVM input directly on the IFR 2975 as shown
in Figure 5-7 (no external load is required as the internal 600 ohm load of the IFR 2975 is used). Inject
-70 dBm RF carrier level into the receiver.
Figure 5-7: Receiver Analog Audio Testing
In the Audio Levels area of the Service section on the RSS, adjust the Rx Balanced Audio Output level
adjustment as shown in Figure 5-8 until -8.0 dBm audio level (0.308 Vrms @ 600 ohms) is measured
on the DVM meter of the IFR 2975 as shown in Figure 5-9. The high and low alarms are set at -7.5
dBm and -8.5 dBm audio levels.
Figure 5-8: RSS Receiver Audio Level Adjustment
VOL
SYSTEM REGULATOR
METER
+
-
MADE IN CANADA
ON
OFF
SPKR INT EXT EXT
SPKR
OFF
POWER ON
2
1
5
4
3
6 7 8
11
10
9
FUNCTION 12
RECEIVER
NORM
SQ. DISABLE
OFF
CNTL
BUS
A D
RF N I
REF
IN
USB
FREQUENCY (MHz)
MADE IN CANADA MODEL # CODE
Rx Balanced Audio Output
(from pins B26 and Z26)
Computer running RSS
USB from
Computer to Rx
T/R port from IFR 2975 to RF IN on Rx
HELP MODE
TAB
SHIFT
+
-
.
BKSP
HOLD
RETURN
ESC ENTER POWER
1 2 ABC 3 DEF
JKL MNO GHI 6 5 4
TUV WXYZ PQRS 9 8 7
# 0 *
VOLUME
SQUELCH
GEN T/R ANT
125 W MAX MIC AUDIO I/O DVM CH2 CH1 SCOPE TEST PORT
100V MAX 100V MAX 100V MAX
DVM port on
IFR 2975