Enough is enough. I tried about every brand and model. I tried (really hard!) to modify/silence them. That worked, to some extent, but it just wasn’t enough. I still can hear these things buzzing on various frequencies. We’re not talking loud signals here, but still enough to make the life of a SWL miserable. Most people who visited me were puzzled, as they didn’t notice the interference at all. Of course they didn’t – as soon as a signal is stronger than, let’s say, S1, you won’t notice it. These people only listened to signals way above the band noise floor. I don’t. I try to detect minimalistic signals which probably would escape to the attention of most other people.
The ones I have now
The power supply I really like (if it would be silent) is the Alinco DM-330MVE. Versatile, powerful and looking great, too.
You can already spot the first hint of trouble when you unbox this PSU and take a look at the front panel. One pot, marked ‘Noise offset’ was put there for a reason – this PSU isn’t quiet. You can’t kill the interference itself, but you can move its frequency. That works, but you keep switching back and forth between the receiver and the PSU in order to get a clean signal. The interference frequencies aren’t stable either, especially when the load changes.
Personally I would like to relabel the text of this pot to ‘WCMSPS’ (We Can’t Make Silent Power Supplies). Although there are some mods available, the outcome still didn’t meet my strict requirements. Yet I won’t sell this one, as it makes a great PSU for my work bench.
The other one I own is the ‘no-frills’ Samlex SEC-1233. Samlex doesn’t try to hide the shortcomings of switching power supplies. A quote from their website:
“Switched mode power supplies (SMPS) employ high frequency switching and thus, are a source of radio interference, a recipient of radio interference and a conduit of radio interference. (Older linear type transformer based power supplies do not employ high frequency switching voltages and will be quieter as compared to switching type of supplies).”
Noise wise, this one is better than the the Alinco, especially after some mods and proper grounding. Still not good enough though. I will sell this one to someone less critical, or someone who is active on VHF/UHF only.
Back to basics
I still have an old fashioned Yaesu FP-800 power supply here, which I use now when operating on HF. I will order a Diamond GSV-3000 later this week, and put my Samlex up for sale. The Diamond isn’t perfect either – the standard rectifier diodes are not up to the task and tend to blow up after a while. Easy to fix when that happens, but I will replace them in advance.