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Quieter fan for the Astron SS-25 power supply


The fan noise from my Astron switching supply was annoying. I had heard complaints about the fan in the IC-7300, but the power supply's was worse.


I replaced the fan with a smaller version of the Noctua quiet fan that YouTubers were suggesting as a replacement for the IC-7300 fan: the Noctua NF-A6x25 PWM, 60mm, brown, available from Amazon. Much quieter!


The fan is an exact fit. It can be used at full power or with the series dropping resistor provided with the fan to quiet the fan further by slowing it slightly.


At the moment I am running the fan constantly at the lower speed because the thermal switch that controls the fan in the power supply is defective. I've ordered a replacement switch but the fan is so quiet, I may leave it running constantly.


The fan cable has four wires. As seen in the fuzzy photo here, #1 on the connector is negative and the wire is black. The one next to it, yellow, is positive. You can ignore the other two.



The fan comes with rubber mounts to replace the original machine bolts in case it vibrates. I used the bolts and have no problem with vibration.


I had seen one complaint on line about the power supply's fan causing RFI when running. I didn't test this but as a precaution, I added a snap-on ferrite bead to the fan leads (see top photo).


I was about to give up on this supply but now it's a keeper.

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