Service BulletinAmateur Radio Division

Subject: TM-732A - 2 Meter Interference on 70 CMDate: May 20, 1992

Reports of 70 cm receiver interference might occur when transmission is attempted on two meters. This is caused by a harmonic relationship that occurs between some 2 meter frequencies and the IF image frequency. The resulting signal enters IC201 (FM HIC) on the 8R line of the 430 MHz TX/RX Unit.

Addition of a chip bead and bypass capacitor on the 8R line will correct this tendency.

Parts Required:
470 pF chip capacitor CK73FBlH471K
Chip bead L92-0131-05

Note: Don't confuse the chip capacitor with the chip bead. They have the same shape. The chip bead is black and the chip capacitor is brown so it should be a simple matter to identify the correct part.

Cut the trace on the 430 TX-RX Unit (X57-4000-XX) thats goes from R219 to R223 (8R Line) and add the chip bead across the cut trace. Then add the chip capacitor from the 8R line to the adjacent ground trace. Put the capacitor next to R219.

This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance.
Time required for this modification is 30 minutes.

©1992 Kenwood U.S.A