#v6 control settings for 12V fan #v6
My experience with fans and uBITX.
Some fans are electrically noisy and can be heard through the audio. I used a squirrel cage fan that was the pits. So if your fan is noisy you might want it on when transmitting only.
Since the fan is cooling off a heat sink it makes sense to me to just run it at a low speed rather than complicate with a sensor or something. I have one that uses an 80 mm fan with big heat sinks and it never gets warm. Found a cat sitting on a morse key for a long period. All was well.
On the last one I put together I isolated the power transistors and bolted them to a 1x1x1/8 aluminum angle stock and riveted the angle stock to the back of the aluminum case. No heat no noise. Super reliable.
Between my wife and I we have 5 BITX radios.
That said I would turn on the fan at maybe 45. Use your hand and see when you think it is too warm. You may have to turn it lower than you think it ideal to keep it from getting hot running a digital mode. They are neat modules we have one driving our chicken brooder pen.
Raduino bracket and Ham_Made_Keys