Service Manual Part 1

  ! -80
  
-8+ #!5
In this Section, deviation settings are given first for wide band, followed by settings for
medium band in brackets ( ) and settings for narrow band in square brackets [ ].
-8+8 3!
Set up the test equipment as shown in Section 4, and select the highest possible
frequency in the operating band.
Set the signal generator to the required receive frequency with modulation set for
±3kHz (±2.4kHz) [±1.5kHz] deviation at 1kHz AF and an output level of
-100dBm.
Using the receiver tuning amplifier circuit shown in Figure 6.2, adjust RV1 until
the voltage of point A equals 3.0V DC, measured on a 1MΩ digital multimeter.
Connect the receiver tuning amplifier to the RSSI output on pin 15 of S14 (logic
PCB) and monitor the output on an oscilloscope (1V/division, DC coupled).
If the output on the oscilloscope is 0V DC, increase the RF input level above
-100dBm until the output level just starts to rise.
Adjust L104, L106, L105, L114, L116 and L203, in this order, to give maximum
amplitude.
A L203 is not used in the T2000-200.
While tuning the coils, adjust the signal generator output so that the level on the
oscilloscope does not exceed 6V DC.
Monitor the audio output at the speaker terminals and adjust L119 for maximum
amplitude.
Set the squelch control (RV153) to minimum and connect a sinad meter across the
speaker terminals.
Decrease the signal generator output until a 12dB sinad is reached.
The signal generator output should not be greater than -117dBm.
Switch to the lowest possible frequency in the operating band, and check that the
receiver sensitivity is better than -117dBm.
 # !0 (( .1
C2
1µF
R3
10k
RV1
100k
(26 turn)
IC1
LM358
1
2
3
+
-
R1
12k
input
f
rom
RSSI
R2
390k
+9V DC
output to
oscilloscope
1V/div.
(DC coupled)
C1
1µF
+
+
A = 3V DC