Do Switch-Mode Power Supplies have a place in your shack?

I decided to give switching power supplies a go. Figured what the heck, i’m tired of this beast of an Astron when I have to take my radio to...

I decided to give switching power supplies a go. Figured what the heck, i’m tired of this beast of an Astron when I have to take my radio to portable events, or when i’m just travelling period. Last I lugged it to a beachhouse @ South Padre Island… never again I said! The Astron weighs 26 pounds, the Alinco DM-330FX pictured below? 4! I drilled through review after review trying to find out if it would introduce hash or interference to my SDR waterfall, I found a few reviews, but there were so few online, I wanted to add my own, and with a video to show just how much interference this switching power supply produces. Each SMPS i’ve encountered is just a bit different than the last in the amount of interference it can produce & the spacing of said RFI.


I had such a good experience with a switching power supply built for my Elecraft KX3 by Pro Audio Engineering called the KX33 that I decided to give this one a go. Note that it says ‘Low RFI’ and not Zero RFI (I was never able to detect the interference from the KX33 though). The  Alinco DM-330FX produces a slight high pitched sound drifting up and down in frequency, and produces some very slight vertical lines in the SDR waterfall about every 35kHz or so. Nothing too noticeable though, heck it took me forever just to find the lines in the first place! But now I know what to listen & look for when i’m using the Alinco. The noise offset feature does work on this thing, if you’ve never had to use it before, that’s great, you probably just haven’t ran into that small sliver of RFI.

Anywho I made a video on it just to show what i’m talking about, but you’ll note that it’s hard to detect in the video, so I gave this little guy 4 stars over on eHam. 5 still goes to the Astron. It may be a beast, but functionally speaking it’s absolutely quiet.

Astrons usually run quite hot, the Alinco runs much cooler, but has a fan on the back that’s a tad quieter than the fan on my Kenwood TM-V71A. I’ve seen other folks throw a small computer case fan on their Astron, maybe I should give that a go!? I threw an Anderson Powerpole pig tail on the back, and had all the features I need now on one little compact unit. I think for normal base station use, the Astron will probably be my goto power supply because i’m on the waterfall quite a bit, now if i’m just leaving my station in monitor mode (which has been quite a bit lately!) I use the SMPS.

Just my .02 🙂

Happy Monday!


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  • Lowell KM4QEG
    5 March 2017 at 7:41 PM

    I have the DM-330 MV (slight variation on a theme) and have never needed the ‘shift’ knob. It appears quiet across the entire HF spectrum. It does stay connected to two 35 AH batteries all the time which would filter any noise on the output leads. Seems to be a good piece of gear. Doesn’t sag under load and has excellent ripple reduction in the output.