Johnson DM3474, Service Manual

Page: 46 / 64

ALIGNMENT PROCEDURE AND PERFORMANCE TESTS
6-4
Part No. 001-3474-002
Figure 6-2 RECEIVER TEST SETUP
6.2.5 RECEIVER ALIGNMENT
C A U T I O N:
Do not key the transmitter with the generator connected! Severe generator damage may result.
1. Connect the test setup shown in Figure 6-2. Adjust the power supply for +7.5V DC.
2. Measure the receive current drain. (Typically current should be <80 mA.)
3. Preset tuning slugs of L222/L224 to the full clockwise position (slug in all the way).
4. Preset C232 to center position (slot in-line with axis of part).
5. Readjust L224 counterclockwise 2 turns.
6.2.6 IF AND AUDIO ADJUSTMENTS
1. Load the synthesizer with the channel frequency.
2. Set the RF signal generator for this frequency with a 1 kHz tone (modulated output shown below) at a level of
-47 dBm (1000
µ
V) and inject into J501.
1.5 kHz deviation (-X10 12.5 kHz BW Radio)
2.4 kHz deviation (-X20 20.0 kHz BW Radio)
3.0 kHz deviation (-X30 25.0 kHz BW Radio)