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Linear Power Supply

Looking in the FAQ ...

We have tested two classes of linear supplies with good results:

There is a group of people who care about quiet power supplies for their digital devices: the audiophile community. And for this purpose there are transformer-based, 5V linear supplies available on Ebay and AliExpress. We have evaluated one of these units and it worked great. All have IEC 60320 C14-style AC input connectors so you can use a mains cord specific to your region.

Jan 2019 update:

We've had a couple reports of the supplies from Ebay above showing up DOA or unable to meet the Kiwi current requirement such that the Kiwi doesn't power up (even though the supply puts out 5V under no-load conditions). The supplies were replaced by the seller, but caveat emptor..


Contacting the Ebay vendor, they say the max current for this psu is actually 1.5 Amps at 5v DC ... and they've just corrected the eBay listing with this information. (Previously it said 4.5A which didn't make sense as 4.5 * 5 = 22.5 Watts ... more than the 15 Watt in the description). This might explain the couple of reports in the "Jan 2019 update".

Comments

  • Interesting.... wonder whta the limter is.... a regulator? Transformer?

    The Acopian 5EB250 isn't plug and play, but DOES handle the current, and often isn't too expensive on ebay. I've seen them mentioned here before for other Kiwis... I've had experience with this style Acopian supply at work, they are fairly bulletproof...


    I know the Bel ones are decent, too. Again, not plug and play though.

    -Nate

    N8BTR

  • edited April 3

    Hello,

    just my experience. After several tests, I chose two Condor HBB512-A+ power supply (SL Power Electronic). The regulatory tests are excellent. It delivers 5 Volts for 3 Amperes (KiwiSDR) and 15 Volts for 0.5 Amperes (active antenna). The two Kiwis each have their own power supply. It is an industrial power supply, it can remain on 24 hours a day without overheating. The two power transistors are well cooled.

    Toleance : the mains voltage (230 Volts AC in France) can vary up to 10%. In any case, the entire installation is on a OneLine inverter (230 Volts at 1%).

    Best regards


  • I know you get what you pay for but these supplies are very expensive here in Australia. Shipping makes a huge difference.

    Im looking for something a bit more economical, any suggestions please ?

  • try the Meanwell MDR-60-5

  • Watch out if you are suing brushless fans connected to the DC supply feeding the KiWi.

    I have just built some linear supplies and found a couple of things.

    There was significant RF noise from the DC regulator (yes really) at frequencies below 1MHz. This is due to noise that is present on the regulator's internal voltage reference source. In one case, the noise was worse than that produced by a good quality switching supply.

    The fan (Sunon Maglev) produced large amounts of RF noise at frequencies below 100kHz. These were harmonics of the internal fan motor driver, and the fundamental frequency varied from a few hundred Hz to >1kHz depending on the motor speed.

    Adding a 10,000uF across the DC rail helped to reduce both noise sources, but the motor noise is difficult to fully suppress.

    Regards,

    Martin

  • Just received a linear power supply from https://www.ebay.com/itm/113160740684

    Works well

    The one thing to watch for is that plugging everything up, then switching on the power supply ... the Kiwi doesn't boot up. You need to switch the PSU on first, then plug in the Kiwi.

    The same thing happens with a iFi SilentPower switch mode plug top supply.

    Whereas the Apple switch mode supplies do boot the Kiwi on a power up. ("They" being a 12 Watt USB-A, 20 Watt USB-C or 61 Watt USB-C).

    I've also been powering the Kiwi on a USB from the iMac and/or a Dell laptop and that's worked fine too.

  • I run my V1 at 5.4v output under load.

    This compensates for the cable, connector, and PCB resistive losses.

    There is 5v when measured at the Beagle header, and it starts on the application of mains to the linear PSU.

    I'd set the PSU volts to give 5v at the Beagle.

    Regards,

    Martin

  • Seems to be more the time it takes for a smoothed supply to get to 5 volts from switch on.

  • Yes, the PSU ramp up / settling time can be an issue, as others have found.

    I have built several linear supplies and the KiWi's always seem to start up OK, despite having a somewhat slow rise time.

    I just wanted to mention the output voltage setting, as I've found it to be almost as important, in case it was a contributory factor to your problem.

    With all linear supplies, make sure there is some type of overvoltage protection. One of my linear supplies was recently subject to a mains surge, which caused the series regulator transistor to go short circuit and output the full unregulated DC voltage. A simple SCR crowbar circuit that I had added on the DC output, tripped and blew a fuse, before any damage was done to the KiWi.

    Switched mode supplies tend to fail to zero output voltage, so they are a lot less risky, but usually generate much more RF noise.

    Regards,

    Martin

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