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IC-765 Distorted RX/ TX PLL Modification | Radioaficion Ham Radio

IC-765 Distorted RX/ TX PLL Modification

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Technical Bulletin

ICOM IC-765 HF ALL BAND TRANSCEIVER

GJ367888

IC-765 Distorted RX/ TX PLL Modification Technical Bulletin

SYMPTOM

Distorted receive and/or transmit audio on one or more bands. Audio may cut out completely. Distortion may be temperature related. Single sideband audio sounds "raspy" or "rough". Selected frequency may show instability.

CAUSE

The trimmer caps in the PLL unit, HPL VCO may have aged and changed values. REPAIR

Replace the following trimmer caps:

C11 10pf with an Icom # 4610000110 12pf unit VCO cap (white)

C20 10pf with an Icom # 4610000110 12pf unit VCO cap (white)

C29 6pf with an Icom # 4610000100 6pf unit VCO cap (red)

C37 6pf with an Icom # 4610000100 6pf unit VCO cap (red)

We recommend that you remove the excessive sealing wax from around the replacement trimmer caps to prevent future contamination. We also recommend that you check for poor solder joints in the LPL VCO section.

The replacement trimmer caps are long-life ceramics. A partial realignment will be required after these trimmers are replaced. See Service Manual for procedure.

Click the attached PDF.

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