Cooling Fan Mod


Problem: 15 hours continues running per day for the FT1000MP makes him a lttle bit hot under his case even if there is only RX in use. The cooling-fan does not operate on RX. Only if the PA-Stage is used the sensor switch the fan on with maximum speed.


Solution: If the fan are running continues with reduced speed (and reduced noise) there will be no more problems with heat in the rig. A simple way to do this shows the circuit-diagram. Lets start with the modification:


Disconnect the power from the FT1000.

Open the upper case. Locate the REG-UNIT on the left side of the rig.

Loosen the two screws from the cooling-fan at the left and right side of the PA-Unit.

Plug out the wire from the fan at the REG-Unit.

Connect Power to the TF1000. Switch the rig on.

Measure at the now open socket on the REG-Unit the two pins. One of them has 13 Volt against ground. Remember this side of the socket and plug!

Disconnect power from the FT1000.

Put the fan-plug in the socket.

Carefully solder a cable at the pin of the plug that has !! N O !! 13Volt to ground! This one is the pin that swiched to ground when sensor in the PA-Unit is getting warm.
To this wire solder a Diode 1N4001 with anode. To the Cathode solder a Resistor of 220 Ohms 2 Watts. The other end of the resistor connect to ground.

Parallel to the resistor put a electrolyte-condenser with 2200 Microfarads and min. 16V Voltage with the positve side towards the diode and the negative side to ground. Ready for takeoff...

How does this modification works?

Well after switching on the FT1000 the 2200 Microfarad C is empty and a loading-current flow from the 13V source via the fan-Motor, via the diode into the capacitor. This current is strong enough to start the motor running. When the Capacitor is charged only the 220 Ohm Resistor limits the current through the fan-motor. His speed and noise is reduced. Maybe you must change the value of this resistor due to the "mechanical wellness" of the fan motor and the noise you can accept for continues running.
By the way, the diode make sense for when the sensor in the PA-Unit switch to ground. This diode protects the switching-transistor from the discharge-current of the electrolyte condenser.

Put all things together, specially take care of the fan by remounting it to the PA-Unit (easy running and no cable around)!

Here in my rig it works well. Cooling fan is running at low speed and low noise continuously. On TX sometimes after long TX-time the fan switched up to his maximum speed and falls down to slow operation after RX is in use.

No warranty of function for this modification. I am not responsible for malfunction of your equipment after doing this modification. Guenter DD9ZO Germany




This site was last updated 08/21/07