Technical Manual

SIGNAL
COUNTER
HF
GENERATOR
SINAD
P671A
OSCILLO-
SCOPE
METER
AUDIO OUT
1kHz MODULATION
INPUT
455kHz
RF IN
10dB
ATTENUATOR
TLA 852/FLA 872
TM1205 Issue 2Page 5 - 22
Figure 5.11: Radio Alignment Test Equipment
5.8 RADIO ALIGNMENT PROCEDURE
5.8.1 Preparation
a) Remove the Board Assembly from the Case (see paragraph 5.5.2).
b) Install a 0 ohm resistor or a shorting link in the position for R456, to disable
the BEC.
c) Disable the AGC circuit by connecting TP403 to 0 volts. Alternatively, lift
R409.
5.8.2 Alignment Procedure
a) Configure the test equipment as shown in Figure 5.11. Set the signal
generator to the channel frequency with an output of -10dBm.
b) Put the Board Assembly in the tray of the P671A Alignment Jig and connect
the frequency counter probe to TP405. Adjust CV405 to give a reading of
455kHz ±50Hz at the frequency counter.
c) Adjust CV406 for maximum amplitude of the 455kHz signal on the
oscilloscope. A minimum of 500 millivolts should be achieved.
d) Remove the AGC disable and assemble the Board Assembly in the case.
Remove the right hand label from the case back to expose the aerial trimmer.