WIRE
LINE
REMOTE
BASE
PHONE
LINE
LEVELS
A.
Phone
Line Levels
1.
Perform the Transmitter Modulation procedure, outlined
in
the previous method, before proceeding with the
phone line level adjustments.
2.
Connect the Analyzer
to
the base station under test as shown in figure 4-17. Connect
RF
In/Out
to the antenna
connector and Mod
Out
-
DVM/Counter
In connector to the station phone line input.
CAUTION
Disconnect the telephone line from the base station
and
connect a 600
ohm
load across the input. Failure
to
do so
will introduce hum
and
noise that will cause erroneous readings.
3.
To
measure levels across a balanced phone line, refer to paragraph D.
To
generate signals across a balanced phone
line, refer to paragraph E.
B.
TRANSMIT Line
Input
1.
Set DISPLAY to DVM, FUNCTION switch to Monitor FM, and MODULATION switch to off. Set
MONITOR
BW switch to narrow
and
squelch control to threshold.
2.
Set 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 setting
or
too tight a squelch setting inhibits the modulation devia-
tion display.
3. Enter the proper transmitter frequency. Move the display cursor down to DVM and enter 1 for
AC
mode.
4. Adjust the 1 KHz Level control for the DBM level expected from the remote control console. The typical value
of
-16 dBm will be
+/-4
dB
of
most actual levels.
5.
Remove the cable from the
DVM/Counter
In connector coming from Mod Out. Connect the cable coming from
the line driver
output
to
DVM/Counter
In.
6. Adjust the exciter level control
on
the station control module for the value stamped
on
the exciter, as indicated
on
the display.
7. Set DISPLAY
to
Oen/Mon
Mtr. Make a line push-to-talk by applying the proper control signal to the input line.
Verify that modulation
is
5 KHz.
C. RECEIVE Line
Output
1.
Disconnect the cable from the Mod
Out
and
DVM/Counter
In connectors. Connect the cable from the receiver
line driver
output
to the
DVM/Counter
In.
2.
Set DISPLAY to
Oen/Mon
Mtr, FUNCTION switch to Generate FM,
and
MODULATION switch
to
off.
3. Adjust the 1 KHz Level control for 5 KHz DEV indicated on the display. Set the attenuator to
-30
dB and the
Variable control to mid-range.
4. Set DISPLAY
to
DVM. Enter the proper receiver frequency. Move the display cursor down to DVM
and
enter 1
for
AC
mode.
5. Adjust the line level control
on
the line driver module for the desired level
on
the phone line. A typical value for
carrier - type lines
is
0 dBm.
4-30
'------/
'----'"
'-...---'
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