Linear Power Supply
Looking in the FAQ ...
We have tested two classes of linear supplies with good results:
- Audiophile power supplies
- Ebay https://www.ebay.com/itm/113160740684
- Cable with 2.1mm plug, ask for 5V output and 110 or 220 VAC input
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
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
I put together a 7805 regulated supply to power a KiwiSDR from a 12v accumulator. Standard circuit with 220nF bypassing of regulator input and output, and 100uF across the output.
As John has warned, the BeagleBone Black draws high initial current, and shuts down if the voltage drops. That seemed to be a problem for mine. Replacing the 100uF capacitor with 1000uF fixed that, but only if the supply is connected to the accumulator BEFORE the BBB.
Oh, and after frying a 7805 with reverse voltage, I added a 1N4004 on the input!
YMMV
Cheers -- Ross
Ross, you could additionally put a schottky diode in forward direction into the 7805's GND line. This would slightly rise the output voltage and give better margins to compensate for losses on traces etc. (Assuming that ~5.3 .. 5.4 V is still okay for the kiwi.)
I recently got the GST25A05-P1J SMPS from KIWI electronics in the Netherlands, added a extra netfilter I found in the junkbox on the AC side and some ferrites on the DC side and AC side and it look pretty clean on the waterfall when on a dummy load.
Also make sure the gauge of your DC power cable is sufficient for the length of the cable and load. Voltage drop can be a problem, especially during peak current draw during startup. May read 5 volts at the output of the power supply, but once 1 or 2 amps are being drawn, you may have something closer to 4.7 volts at the Kiwi.
If your power supply doesn't rise fast enough, you can implement a time delay-on relay to switch the output on a few seconds after the power supply was energized.
Good evening everyone,
exactly.
I would like to add a few ideas. Be careful with power supplies intended for analog audio electronics and HiFi, whether they are made for professionals or amateurs (power supplies for audiophile). In order to protect analog audio circuits, it is common for the designer to voluntarily provide for a gradual increase in the DC voltage. I work with a lot of devices that are like this (electronic tubes, but also transistor circuits guaranteeing great sound dynamics).
For microcomputers, it's quite the opposite. The power supply must provide the requested voltage as quickly as possible (a rise time well below a millisecond. In the world of computing, we therefore prefer switching power supplies, which are faster and whose regulation dynamic range is significantly larger.
But for the Kiwi, I agree that a high quality linear power supply is necessary. We always gain in noise.
I chose 5 volts under 3A (linear) with a regulation rise time of 100 microseconds, for my two Kiwis. And above all, independent power supply for every Kiwi.
——
Your sector filtering seems effective to me. It must be checked with the connected ground of the antenna, in order to ensure the absence of a ground loop, with regard to the power supply. Sometimes it's a real headache.
Best regard, Philippe
Hello,
My homebrewed PSU seems a little bit oldschool and oversized. Transformer 120 VA and a regulator IC µA78H05SC, in a TO-3 housing and mounted on a 0.5°/Watt heatsink.
The heatsink temperature reaches 35° Celsius on an ambient temperature of 27° Celsius without cooling fan.
Sometimes you need for power cycling wait a few seconds for discharging the 10000µF/25V condensor and the 470µF/16V condensor on the output. Or, if Kiwi does not start immediately, 5V plug remove and plug in again. That works.
Best regards
Adding some pictures. Main problem was, to get an appropriate metal case, which does not produce an extra acoustic hum by magnetizing caused of housing sheet iron
And the remaining noise spectrum is caused by the internet access router itself, LAN cable and so on. If router is switched off, the QRM between approx. 7 and 14 MHz disappears instantly. (On local operation mode that interference is no more there either.) Conclusion: Antenna needing be placed more outside the "disturbing fog", and router and LAN cables needing better screening, too. I'll keep still busy on that issues.
Acopian VA5H3200 5vDC 32A regulated linear power supply. APC Line-R AVR on the AC side. A couple of ferrites on the KiwiSDR power cable. An USB cable with integrated ferrites to a cheap USB hub for powering various accessories, which at the moment is connected via an USB cable with integrated ferrites feeding a TP-Link TL-WR802N for bridging the Kiwi to WiFi. 75-ohm CATV terminator on the main antenna port. GPS antenna connected. Waterfall down to -150dB.
Pretty much flat from LW to 30MHz. If looking very close the noise profile *slightly* increases under 20KHz, but "whatever" IMO.