I work with terrestrial point-to-point microwaves and one particular model has a high-power amplifier that includes two four-inch fans. When I upgraded two such microwaves in my area I noticed that the heat sinks were too hot to touch for very long.
When I looked at the fan installation, I saw that from front to back, the power amplifier was heat sink on the back of the radio, circuit board, and sheet metal covering on the front of the radio. The fan was on the front side blowing against the sheet metal so the heat sink never got a puff of air.
These fans were your standard computer type, four-inch square fans sold to us for more than $1,000 because they had an alarm wire that had never been implemented. I took a 1-inch square fan and put it at the bottom of the heat sink blowing up and ran it through a dropping resistor to allow 10 volts instead of the 12 volts it was made for. I figured that would let it run forever. That was 10 years ago and to this day the heat sinks are slightly warm to the touch and the 4-inch fans are in a storage cabinet.
Tell us your experiences with Monkey-designed products. Send stories to Lauren Muskett for Made by Monkeys.