Symptom:
A transmitter spur might be present at a dial frequency of xx.xx1 MHz. This spur (fo +/- 1 KHz) is quite small (-55 dB relative to fo) but might become noticeable when the transceiver is used with a linear amplifier.
Cause:
The transmitted signal enters pin 5 of IC11 which is in the last PLL loop in the AF unit due to RF feedback. This pin is the input for the 10 MHz Ref. Osc. signal from the CAR unit. IC11 is the source of the spurious signal since both the band and 10 MHz frequencies are divided by the 500 KHz comparison frequency supplies by IC11.
Correct action:
To reduce this RF feedback increase the Ref. Osc. level from .2 V to .7 V ms by adding the accompanying circuit to the input of IC11.
Parts required:
Qty Description Kenwood Part No. Circuit description
1 12 µH Ferri-inductor L40-1201-17 NA
1 10 pF Chip capacitor CC73FCH1H100J NA
1 16 pF Chip capacitor CC73FCH1H160J NA
 
Caution: 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 or less.
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