About 1 mV noise is present at the speaker or headphone jack in the receive mode with the AF GAIN control set to minimum. If the transceiver is in the CW mode, a faint tone might also be heard through the headphones (sidetone leakage). The following modification will reduce the level of the noise and the tone.
Required parts:
2SD1257K(S)
- Disconnect the power cord and antenna.
- Remove the top and bottom covers (18 screws).
- Locate the RF unit on the bottom of the transceiver. This is the back left board of the four boards on the bottom of the transceiver.
- Remove the screws from the AF unit and disconnect the plugs as necessary to turn the board over to expose the foil side of the board.
- Replace Q6 with a 2SD1757K(S).
- Solder a 22 AWG jumper wire as shown in figure 1.
This modification may be covered under warranty.
Time required to perform the modification is 1 hour or less.
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