The IC-706MKI has a fan running permanently – at lower speeds when receiving, and after locking it starts at full speed. As the fan wears out, it becomes noisier and noisier. It is advisable to buy a new one and replace it. Even after this operation, however, the noise is still disturbing, especially when the device is squelched.
The fact that it is quite unpleasant is evidenced by the number of adjustments. However, most of them are complicated. If you do not want to bother the IC-706 with full power in FM, RTTY or SSTV on HF, a very simple solution is offered. Add a braking resistor to the fan supply, which will reduce the speed during reception and transmission. The procedure is quite simple.
IC-706 adjustment procedure
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IC-706 MKI Turn off TCVR
- Disconnect all cables
- Remove the bottom cover of the IC-706 by loosening the screw socket.
- Two wires lead from the printed circuit board to the fan
- Cut one of them and connect a 100 ohm trimmer there.
- Connect the power cable. Set the power supply to a lower voltage (approx. 11V) so that the fan will start under all conditions later.
- Turn the impeller to find the point where the fan stops. Try turning the TCVR off and on to see if it starts.
- Use an ohmmeter to check the resistance value and replace the trimmer with a fixed resistor. Don't forget to insulate everything carefully! In my case it was 18 ohms.
- Cover the TCVR
The temperature of the IC-706 increases only imperceptibly, while the noise level during reception drops by half, and during transmission by a quarter. I did not notice any problems with overheating.