With some TS-440S transceivers, insufficient modulation may occur when the MC-85 compression switch is turned on. This may be caused by too much of a voltage drop across resistor R172 on the IF unit of the transceiver . If this is found to be the case, change the resistor from 1K ohm to 100 ohms.
Required part
100 Ohm, 1/6 Watt resistor (RD14CB2C101J)
PROCEDURE:
- Disconnect the power supply and antenna from the transceiver.
- Using a #2 Phillips screw driver, remove the 9 screws from the top cover of the transceiver. Remove the cover and unplug the speaker wire.
- Locate resistor R172 on the component side of the IF board (Figure 1).
- Using a #1 Phillips screw driver, remove the 7 screws that secure the IF unit to the chassis of the
transceiver.
- Pull the board up and rotate it towards the front of the transceiver to expose the foil side of the board.
- Desolder and remove resistor R172 from the board.
- Install and solder the 100 ohm resistor in place of R172.
- Assemble the transceiver by reversing steps 1 - 5.
This modification may be covered under warranty.
Time required for this modification is 0.5 hrs or less.
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