Alignment Of Receiver Section - Radio Shack TRC-447 Service Manual

ALIGNMENT OF RECEIVER SECTION

Test Equipment Required and Connections
• DC power supply: 13.8 V
• Signal generator (SG) (27.205 MHz, 1 kHz, 30% AM modulation, output inpedance 50-ohm): CB
• SINAD Meter
Preset
• ALERT/WX/CB: CB
Alignment Procedure
Step Preset to
Vol.: Max.
1 SQ.: Min.
RX: 20 CH
Vol.: Standard
2 SQ.: Min.
RX: 20 CH
Vol.: Standard
20 CH
3
SQ.: Max.
Vol.: Standard
4 SQ.: Min.
RX: 20 CH
5 WX: 3 CH
6 WX: 3 CH
• AC voltmeter
(162.45 MHz, 1 kHz, ±3kHz Dev. FM modulation, output impedance 50-ohm): WX
• Distortion meter
Signal Generator
Transceiver
ANT
Jack
J501
Adjustment
Connect the SG to the antenna jack (J501) and the AC voltmeter
L3, L1, L7, L5 across the dummy load (8-ohm) to the external speaker jack (J3).
L6, L2 Adjust coil (L1 ~ L7) to obtain the maximum reading on the AC
voltmeter with keeping the level of the SG.
Set the output level of SG to 1 mV (−47 dBm).
L4 Adjust coil L4 to obtain minimum Reading on the Distortion
Meter.
Set the output level of SG to 1 mV (−47 dBm).
RT1
Adjust RT1 so SQ just opens.
Set the output level of SG to 100 µV (−67 dBm).
RT2
Adjust RT2 to position the indicator in the meter MT501 just on
"SIG9".
Set the output level of SG to 100 µV (−67 dBm) No modulation.
L103
Adjust coil to obtain the maximum reading on the AC voltmeter.
Set the output level of SG to SINAD 15 dB.
RT101
Adjust RT101 so SQ just opens.
• Dummy load (8-ohm, 5 W resistive)
AC Voltmeter
EXT.
SP .
J3
Remarks
— 8 —
Distortion Meter
SINAD Meter
Dummy Load
(8-ohm)