Does this PSU seem adequate for two KiwiSDR's?

While testing a new KiwiSDR + BBG, I've been powering it with this PSU:

https://www.amazon.com/gp/product/B07T44S4MV

The output amperage is stated differently in several places, but it appears to be 3.5A.

I'm planning to add a second KiwiSDR. Does the above PSU seem as though it would be adequate for two? I see it stated here that the receivers peak at about 1.5A each.

Comments

  • While that might work for two Kiwis, especially if they start at different times, some of us have turned to an inexpensive alternative. While these run from DC rather than mains AC and one has to provide that separately, and while they are SMPS so do have fast edges capable of QRMing a Kiwi, they run at ~ 1MHz and in practice can work very well.

    You might want to consider trying these, one per Kiwi, from whatever inexpensive ~12V DC supply you might have battery or otherwise before going the route you ask about. SUch a solution could be more flexible and cheaper.

  • Thanks, I've seen those mentioned, and they're certainly inexpensive to try.

    Are certain bands known to be affected more by noise from the buck converters?

  • PS noise is generally due to conducted, common mode noise current. The Kiwi is pretty impervious to differential noise so more C's or series L's don't usually help.

    These small, cheap supplies have a high switching frequency and because they are small and by design most circulating currents are contained within them rather than injected on the input and output lines.

    It's not uncommon to not be able to even find the ~960 kHz fundamental or its harmonics anywhere in an operating Kiwi. I use them on receivers that reach or exceed the ITU propagated noise floor.

    I suggest identifying the frequency of the line and verifying that it is not an impairment to Kiwi operation at first but other than setting the V to 5.25VDC or so ahead of time and perhaps shrink tube wrapping the whole thing (takes a larger diameter shrink to fit but they are pretty small so should be available) it's not necessary to do much.

  • edited April 7

    On the original PSU question, I have a similar (internal transformer) linear and it would run two standard Kiwi's without issue but as n6gn highlights, the issues are most problematic at boot so if you have a momentary power failure there is a small chance that one or more would not boot due to the strict power control on the BeagleBone.

    The UK listed version calls it a 25W PSU but says don't add anything else after 3.5A,5.1V (17.85W) which is more realistic (and fine for two BBG Kiwi's).

    I think I also went down the small DC-DC (MP1584 based) after seeing it mentioned on here and they are remarkable considering the cost and size. I fed them from "AnyOld" 12V linear supply or 12V lead acid from solar, knowing the supply to them can be up to 28V (I think) gives a nice level of protection.

    Don't be tempted to "Upgrade" to the larger DC-DC (LM2596) with multiturn pots and up to 35V input, 3.5A out as they are much noisier in my experience.

  • Thanks, I'll try using the 5V 3.5A PSU with the two KiwiSDR's for now, then work with the buck converters. It would be nice to consolidate all 12vdc and 5vdc devices to use a single power source.

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