A Tale of Two Power Supplies

21 Feb 2022

Generic PS Spectrum

KiwiSDR waterfall with generic SMPS

Generic PS

Generic SMPS

I’m a bit startled at how difficult it is to find old-fashioned, linear power supplies these days. While I have acquired a couple of 5 volt, 3 amp units specifically for use with the KiwiSDR, I still have some work to do to get the needed wiring and plumbing done.

In the meantime, while pawing through my junk box, I came across a switch mode power supply (SMPS) that I recall was the one that came from Seeed Studio with my KiwiSDR.

As an experiment, I swapped out the generic SMPS I’d been using with the KiwiSDR for the original SMPS provided with it.

Kiwi PS Spectrum

KiwiSDR waterfall with Kiwi-provided PS

Kiwi PS


Kiwi-provided SMPS

I was kind of startled at the difference: The original SMPS is much better below 10 MHz, and especially in the area between MW and 7 MHz, but it is a lot worse in the 15 - 30 MHz range.

I’m anxious to get the linear 5 volt supply hooked up to see what kind of difference it will make. As per the advice at the KiwiSDR site, getting a quiet power supply seems to be a key factor in reducing “self-noise”.