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IC706 MKIIg COOLING FANS MODIFICATION

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Unlike the previous versions,the internal cooling fan of the ICOM MKIIg is kept off,when not transmitting.

When transmitting,a temperature activated switch will start the fan if the temperature goes above 60 °C.

With this simple modification,it will be possible to keep the internal cooling fan on,running at reduced speed,when in receive mode.

The purpose of this mod is to supply 4,7 V to the fan (in RX mode).

This voltage value is the best compromise in terms of air flow and noise.

All is needed is a 200 ohm,1 watt resistor (or a series of two resistor of 100 ohm each),between the power supply socket of the fan and the main power supply of the board.

In the pictures are shown the points were the resistor will have to be connected: the socket with the black and red wires feeds the power to the fan,while on the impedance (picture 1) it's available the power to the main board (13,8 Vdc).

The connection of the resistor to the fan can be done in two different ways:

it can be soldered directly to the + (red wire) pin of the socket,as shown in the picture 2,

or just forcing the resistor lead in the small gap between the white plastic and the metal of the plug,as shown in the picture 3.

PICTURE 1

PICTURE 2

PICTURE 3

An additional fan can be installed externally,right on the heat sink.

It should be oriented in such a way that the air will be "pulled" from inside out,this will help to keep the internal temperature down.

To fix the fan on the heat sink I've used two small Fisher plugs,stuck into the blades.

The fan will be held in position with two screws,screwed on the two plugs.

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