IC-735 HF ALL BAND TRANSCEIVER
IC-735 Distorted RX and TX PLL Modification Technical Bulletin
Distorted receive and/or transmit audio on one or more bands. Distortion may be temperature related. Single sideband audio sounds "raspy" or "rough ". Selected frequency may show instability.
The trimmer caps in the PL unit (HPL VCO), and Reference Oscillator unit may have aged and changed values.
Replace the following trimmer caps:
C37 10pf with an Icom # 4610000110 12pf unit vco cap (white)
C45 10pf with an Icom # 4610000110 12pf unit vco cap (white)
C52 6pf with an Icom # 4610000100 6pf unit vco cap (red)
C59 6pf with an Icom # 4610000100 6pf unit vco cap (red)
C138 6pf with an Icom # 4610000100 6pf unit REF osc (red)
The replacement trimmer caps are long-life ceramics. A partial realignment will be required after these trimmers are replaced. See Service Manual for procedure.