The Hum in My Receiver Went Away When I Changed One Box

The hum showed up about a week after I set up the bench. I would tune across 40 meters and hear it under every signal, a steady whine that never quite went away no matter where I landed the dial. At first I blamed the radio. Then I blamed the antenna. Then I unplugged the power supply and the hum vanished, and I felt a little foolish, being a retired telephone company lineman and all. The fix was a different box on the bench: the Tekpower TP30SWI 30 amp DC 13.8V switching power supply.

I came up in the telephone world, so I know a little about dirty power. I spent thirty years climbing poles and tracing trouble, and half of what we chased was noise. A bad transformer, a corroded connection, a charger left plugged in somewhere it did not belong. It is the same story on a bench. Every radio needs clean DC, and not every box that makes DC makes it clean.

I got my Technician license in 2009 and upgraded to General in 2012, so I have been at this long enough to know what a receiver should sound like. The supply I had before the Tekpower was a switching unit too, cheaper and older, and it worked fine for years. It worked the way a screen door works: it kept the bugs out, and you did not ask it for much else. Somewhere along the way it started letting its own switching noise leak into the receiver. The radio would hear the band, and it would hear the supply, and the supply always won.

I bought the Tekpower about two years ago, when I rebuilt the whole setup after my old handheld finally gave out. That 2009 handheld had been my only radio for a long time, and when it died I took the chance to do things right. New radio for the truck, new antenna, and a proper supply for the bench. The Tekpower TP30SWI was the piece I had the least doubt about, and it turned out to be the piece I noticed the most.

The hum did not just get quieter. It went away. I can sit on 40 meters now and hear band noise and stations and nothing else. That is the whole story in one sentence, but let me back up and tell you how I use the thing, because the way it sits in my setup is the reason I would buy it again. The long-term review has the details if you want them.

I can sit on 40 meters now and hear band noise and stations and nothing else. No whine, no hash, no hum.

The practical details are simple. It puts out 13.8 volts, which is what my AnyTone AT-778UVII wants, and it is rated for 30 amps, which is more than that radio will ever draw. I run the mobile radio on the bench off this supply whenever I want to operate from home instead of the truck, and the radio's current meter barely moves. The supply does not strain, and the fan does not run constantly, which matters more than it sounds like it should when you are trying to hear a weak signal.

The feature that sold me, the noise offset, is the one I was most skeptical about. Switching supplies make their own radio noise by nature, and the Tekpower lets you nudge the switching frequency off the band you are listening to. I figured it would be a knob I turned once and forgot. It is, but that is the point. The whine I used to hear sits somewhere else now, and I have not touched the adjustment since the week I installed it.

I will say this about the cheaper supply I compared it with. The Pyle unit is a perfectly honest box for someone who just needs amps and does not care about the noise floor. It puts out the same 13.8 volts and the same 30 amps, and it is cheaper. But the noise offset on the Tekpower is the difference between hearing the band and hearing the supply. For the kind of listening I do, that difference is worth the extra money. If you want the full breakdown, that comparison is written up separately.

Storm season is when the Tekpower earns its keep. When the weather map shows something ugly coming, I pull the AnyTone out of the F-150, bring it inside, and run it on the bench off this supply. Joan keeps the handheld charged on the kitchen counter, and I have the higher-power station set up in the spare bedroom, both of us ready. The 2020 ice storm taught us that a county can go dark for four days, and we do not treat that as a scare story. We treat it as a reason to be ready.

I have owned the Tekpower for about two years now, and nothing about it has changed my opinion. It sits on the bench, it does its job, and I do not think about it, which is exactly what I want from a power supply. The radios are the interesting part of this hobby. The box that feeds them should be boring. This one is. If you want the plain-language reasons a 13.8V supply belongs on a ham bench, I have those written down too.

What I'd Tell You If We Were Sitting at My Kitchen Table

If we were sitting at my kitchen table, I would tell you this. Do not buy the cheapest supply that lights up, and do not buy the most expensive one either. Buy a clean 13.8V supply with enough amps for the radio you actually run. If you hear hash in the receiver that moves when you touch the supply, try a noise offset before you pull your antenna down for the third time. A power supply is a ten-year purchase. It is worth getting one that does not hum.