Hardrock-50 (HR50) Dual 92mm Fan Mod

thingiverse

This is a simple model for adding a pair of 92mm fans to a Hardrock-50 amplifier. To implement this, I took a tap off the 12V line that powers the ATU to power two 92mm fans. I fed the wires through the two threaded holes that remained unused on the heatsink and terminated it to a standard 2-pin fan connector. I also soldered a feedthrough capacitor to the fan wiring and added a couple of ferrite beads to help mitigate RF noise. Initially, I found that there was RF noise generated by the fans but this was only the case when using the DC-DC boost converter recommended by Jim WA2EUJ. I just received a Mean Well power supply that can produce 50v at >4A which I purchased from TRC Electronics and have found that there is no RF noise when using it. I suspect the noise that appeared when plugging in the fans was actually a distortion of noise generated by the boost converter. I've found that I can run the amp at 100% power on digital without exceeding much beyond 50C when using this fan mod. It hovers between 40-45C when rag chewing on SSB. Overall, I highly recommend using this mod if you find your temps creeping above 60-70C during SSB or if you want to run digital at higher powers.