Power Supply Considerations

I have put about 10 KiwiSDR into service over the years and here's a few thoughts on PSU

  • "wall warts" are varied, as there as older linear ones, simple chargers, switchers with actual filtering for RFI/EMI
  • assume warts to be suspect and test them thoroughly for both radiated and conducted noise
  • Linear PSU are almost always a safe choice but are inefficient and their power consumption impacts your electric bill and any UPS run-time
  • Industrial Switcher Units are usually quiet and usable
  • I am using Meanwell DIN Rail mounted PSU in a few installations and they are available on Amazon, reasonably priced, and appear to be quiet.


  • I used switched mode supplies nearly all the time these days.

    The only problem I occasionally find is that despite lots of filtering it is very difficult to entirely remove the switching noise on the VLF bands, typically <100 kHz that is produced by older designs.

    More mosern deigns with switching frequencies in the region of 1 to 2 MHz are a lot easier to filter and are also generally more efficient.



  • After starting a new receiver on short waves, I received interference from a switching power supply. Partially they were reduced by a power filter in front of the 220 volt outlet. I'm thinking of using a 12 volt transformer power supply and a 5 volt switching converter with a high frequency of 1.5 MHz. I remember someone already sharing this idea here on the forum. But I can't find this thread. Can someone remember? Thank you!

  • Search the forum for MP1584



  • edited March 10

    Martin, this is exactly what I was looking for. Thank you for experimenting with the power supply!

    In most of the ready-made modules, a 100kOhm resistor is installed on the MP1584, which sets the frequency of PWM operation. You can reduce its resistance and raise the frequency from 1 MHz to 1.5 MHz. Perhaps this will further reduce interference.

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