As part of my job, I run the occasional electro-magnetic interference (EMI) sweeps. I was curious about the Supernight power supply, and so ran a conducted and radiated emissions sweep. Here are the results:
So this is the conducted emissions, the stuff on the output of the power supply. The power supply was fed 120V 60Hz, adjusted to 13.85V output, and loaded with a 2-ohm load.

This is the radiated energy, from 150kHz to 60MHz.
From these I would guess that these units, while useable, will still raise the noise floor a bit. I plan on using them with some additional filtering. They certainly are a good deal for the price.
73 WD4LUJ
| DL4NO | 2020-09-23 | |
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| A 12-Volt 30 Amp Power Supply -- EMI Sweeps | ||
| There are several remarks needed: * RFI is important for a load of 1-3 A. when the rig is in receive mode. During transmit the question mostly is if the power supply creates 150 kHz sidelines in the TX spectrum. * A 30 A power supply implies some bigger antenna system. To a large extend, RFI is wire-bound and can be removed from the RX input by common-mode yokes and other means. I have experimented a lot with switching regulators. If you implement them reasonably, they are quite silent. | ||
| VE3WGO | 2020-07-27 | |
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| A 12-Volt 30 Amp Power Supply -- EMI Sweeps | ||
| you would need to keep this supply well away from your HF radio and antennas. Isn't s9 = 34 dBuV? (conducted) so these birdies every 27 kHz or so are well over S9 well into the 160 through 20 meter bands near the supply. I am tired of birdies from switching supplies for my HF radios; I just use a nice linear Astron, and I use the switchers for my FM rigs. | ||
| K6JRW | 2020-07-12 | |
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| A 12-Volt 30 Amp Power Supply -- EMI Sweeps | ||
| I'm running a TS480HX (200w) using an old Kenwood PS-30 + a who knows 20A power supply to provide the 40A max required. I rarely push the rig to 200w so do think this power supply would work ok? | ||
| WD4LUJ | 2020-07-03 | |
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| Re: A 12-Volt 30 Amp Power Supply -- EMI Sweeps | ||
| The radiated measurements were taken at the 1 meter standard for DO-160. Reply to a comment by : NX0E on 2020-07-02 You may have measured the "radiated" near fields but I doubt they are actually radiated, especially at frequencies below 30 MHz or so. Your measurements were likely taken way too close to the EUT to actually be radiated. Most radiated emissions testing I've seen were taken in 10m chambers at 30 MHz and above. | ||
| NX0E | 2020-07-02 | |
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| A 12-Volt 30 Amp Power Supply -- EMI Sweeps | ||
| You may have measured the "radiated" near fields but I doubt they are actually radiated, especially at frequencies below 30 MHz or so. Your measurements were likely taken way too close to the EUT to actually be radiated. Most radiated emissions testing I've seen were taken in 10m chambers at 30 MHz and above. | ||
| NA6O | 2020-07-01 | |
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| A 12-Volt 30 Amp Power Supply -- EMI Sweeps | ||
| Nice to see someone do some actual testing and show the results. Offhand, I'd say this particular one looks fine on the output and probably won't be a significant RFI source unless your antennas are extremely close. Among the switching supplies I've evaluated, output EMI is often less of a problem than conducted emissions at the AC line input. I post detailed reviews with pre-FCC Part 15(b) compliance test on my RFI website. There's a review of the popular and very cheap HP 12/750W server supplies there. One issue that is often ignored: It's difficult to adjust any of these supplies to the more desirable 13.8 V range, which significantly reduces IMD in all modern 100W transceivers. http://wb9jps.com/Gary_Johnson/RFI.html | ||
| KJ4DGE | 2020-06-30 | |
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| A 12-Volt 30 Amp Power Supply -- EMI Sweeps | ||
| I think the filtering of a 24.00 power supply sounds cool, please let us know what you do to achieve this. I have been using one of these on the Xiegu G90. | ||