The All-band HF Amateur Radio Transceiver: Just waiting to be modified
Rob AG5OV picked up a cheap temp fan relay from Amazon.
These are also available on Aliexpress for less than US$2.00.
Rob superglued the probe to one of the heatsinks on the finals and then played with ON temp and hysteresis temp. He settled on 50deg for turning ON the fan and 35deg for turning it OFF. Rob says it works great.
Arvo KD9XLC has put one of these 12v fans that cost less than a dollar on the back of his Excelway case from Bangood (which apparently now on sale for $8.88).
You could attach the fan to the cabinet with hot glue, or use the correctly sized bolts/nuts.
And if you don’t want those fans to run on receive connect them to the TX 12v line, namely at pin 3 on U2, which is what Arvo did.
