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A state of the art replacement for the power supply fan on a Kenwood TS930S

Every owner of a TS930S transceiver knows the annoying noise of the fan at the back right of the power supply’s heat sink.
The cause of the noise is mainly the fan motor, which gets louder with age and hard to find as a new spare part:

The original power supply fan in a Kenwood TS930S

Another disadvantage is the cyclic on/off switching of the fan, which is controlled by the AVR unit by a temperature sensor on the heat sink.

I have developed this fan unit as a silent replacement for the original fan and to improve the ventilation of the power supply:

The new TS930S FAN KIT



The TS930S FAN UNIT is available from RF-SYSTEM‘s webshop.

The fan on this kit is always active, but the speed is controlled automatically. Therefore a thermal sensors detect the temperature of the airflow and adjust automatically the speed of the fan accordingly with a temperature controlled linear voltage regulator.

To check the function of the fan, there is also a timer circuit that enable the fan at it maximum speed for a few seconds after the TS930 is turned on.

In addition, the minimum fan speed can be adjusted via a trimmer on the board (see also the “FAN SPEED” labeled trimmer hole on the back side).

Is fixed with the four original screws through the holes for the original fan support frame, maintaining the original look of your transceiver.

The original fan TS930S:


The new TS930S FAN KIT:

The supply voltage (from 28VDC to 48VDC) for this dual fan assembly is taken directly from 28VDC output of the POWER SUPPLY UNIT, mounted directly behind the heat sink:

The black (GND) and red wire (+) soldered on the fan unit should be connected at this points in the schematic:

And here the final result: