Thermal Modification - Yaesu FT-100 Undocumented

After the factory mod.
The SWR icon with an 'X' next to it indicates that the SWR is out of range. If you see an
SWR icon with an 'O' next to it flash momentarily, it is an indication that the antenna has
finished tuning and the SWR is 'OK'.

Thermal modification

The cooling fans will only work during transmission when the radio is tuned to 70.500
MHz or higher. Yaesu will fix this by mounting a thermal switch that bypasses the
electronic fan control circuit. The thermal mod is done on an 'as requested' basis since
Yaesu feels that keeping the fans off in V/U receive poses no threat of overheating the
radio.
A simpler way to do it yourself is to add a 50 to 120 ohm / 1 Watt resistor between one of
the black wires of the fans and ground, for instance the chassis. The resistor value will
determine the idle speed of the fans. Pick one that suits your preferences.
The pictures below show the Yaesu factory modification:
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