I have obtained the tech manual from Radio Shack. There are several alignments required. In case anyone runs into the same problem, here is the alignment procedure.
An FM signal generator, SINAD meter, voltmeter, THD / distortion meter, and oscilloscope are required.
For steps 1 to 3, a 39 nH inductor is required at the L1 position on the receiver board.
- With channel 4 active: measure the DC voltage on TP4 and align L8 to 2.5 V.
- With channel 4 active: Set FM RF signal generator to 100 uV and 162.475 MHz signal: Adjust L2 for max output level and minimum THD.
3: With channel 4 active: Set FM RF signal generator to 5 uV and 162.475 MHz signal: Adjust L1, L3, L4 and L6, L8 in sequence for maximum SINAD output.
4: With channel 4 active: Set FM RF signal generator to 0.6 uV and 162.475 MHz signal: Adjust L1, L3 L4 and L6, L8 for maximum SINAD output (better than 15 dB SINAD).
5: With channel 4 active: Set FM RF signal generator to 0.4 uV and 162.475 MHz signal: Slightly adjust L2 for the best SINAD output on.
6: Repeat steps 3 to 5 to obtain the best SINAD output (better than 15 dB SINAD).
7: With channel 4 active: Set FM RF signal generator to 100 uV and 162.475 MHz signal with 1.4 KHz audio modulation: Adjust VR3 to the point where the voltage on TP3 to ground changes from 0 V to 5V.
8: With channel 4 active: Set FM RF signal generator to 100 uV and 162.475 MHz signal with 2.3 KHz audio modulation: Slightly adjust VR2, if necessary, to the point where the voltage on TP3 to ground changes from 0 V to 5 V.