Astron brand no matter what! I have a pair of Astron 50 Amp linear supplies with voltage and amperage meters (RS-50M) that I bought in 1982. They were online and loaded continuously from 1982 until 2022 when I dismantled the ham shack to move to another room. That was a total of 80 fail-free power supply years which is outstanding!
Admittedly, one of the supplies has failed this year (2023) in the new ham shack location. The failure mode is 60 Hz (AC) hum being heard on the transmitted signal of a 2 Meter 50 Watt base station. No AC hum is heard on received signals nor during squelched standby operations. Moving the same 2 Meter 50 Watt base station to the other power supply renders a clean transmitted signal at 50 Watts. Therefore the trouble is clearly in the first power supply which now sits on the test bench awaiting troubleshooting efforts. It saw a good life of 40 fail-free years and should be relatively easy to find the faulty component(s) once I find time to look at it. I’ll probably re-cap the electrolytics while I have it opened up too.
In summary, if I were to buy another 12 VDC power supply of any amperage, it will definitely meet two mandatory requirements:
1. It must be an Astron. Nothing else is acceptable even if Astron charged me double the MSRP and “Brand B” offered me double my amperage requirements and gave me their power supplies for free. I’m that serious about Astron power supplies powering my equipment!
2. It must be a linear design. A switching power supply inherently switches or oscillates. Yes, they have cut down on their “RF noise” that they generate but a linear power supply will still be quieter. But perhaps more important than that attribute, is the complexity factor. Switching power supplies have more complex circuitry than a linear power supply. That is important when it comes to troubleshooting a rare failure as in my case. The circuitry is so simple that it can be easily hand-drawn and easily understood. Try that on a “switcher”. You say that you’re not into troubleshooting? Circuit complexity in switching power supplies also equates to shorter MTBFs (Mean Time Between Failures). The more components that are involved or the more complex a substrate component is, that mathematically counts against long MTBFs that linear power supplies exhibit. While switching power supplies are doing better spec-wise, I don’t think you will ever see them meet or surpass linear power supplies. This is especially true in the Mil-Spec world where you simply don’t want things to fail at the wrong time. In many cases, lives are at stake and only equipment with extremely high MTBFs get selected.
Sooooooo… For those reading this thread, which type of power supply would you choose to protect day-in and day-out that nice, expensive ham station you’ve spent a few long years (if not more) building from the ground up?
73 es sleep well at night for those that leave their equipment on 24/7/365, Dave K4EET