Thursday, June 24, 2021

More Research on USB Power Bank Use With QRP Transceivers: Qualcomm Quick-Charge

Good news, everybody!

No, this isn't Futurama, but sometimes I think it should be. There are wonderful things happening in the tech world in recent years, wonderful things that stagger the mind.

Even the small stuff is really, really cool!

In my presentation, I mentioned that the PD trigger boards I use for my "magic cables" can't help with non-PD power banks that have "QC", or Qualcomm Quick-Charge protocol instead. I proposed that it be the topic of yet another article, and that someone else interested in it might want to write it. Well, I take that back.

Because this is my article for just that!

I happened to check to see if QC could even be used for this, and found already-extant boards for Quick-Charge that pretty much do the same thing as the PD trigger boards. Moreover, there are pre-made cables in a variety of voltages! QC doesn't provide the high power that PD does, but the top voltage it provides is 12 volts, at 1.5 amps! This is perfectly adequate for all of my 5w QRP radios!

There's only one very small snag...if you even see it that way. The pre-made cables I've found have 5.5x2.5mm barrel connectors on them. Most QRP radios are sold with 5.5x2.1mm sockets, including the Elecraft KX3 and my HobbyPCB IQ32. So I looked for -- and found -- 2.5mm pin to 2.1mm pin adapters. I bought a couple of cables and a couple of adapters. The last piece arrived an hour ago. I plugged a cable into an adapter, plugged that into my IQ32, and checked my power banks for the QC legend on one of the USB-A sockets. Finding one, I plugged it in and flipped the switch on the radio.

It started right up. Turning on the external speaker, the 80m CW segment blasting from it. It works quite nicely! I haven't done any stress testing or timed operations, but it appears to work just fine. There are some very new versions of QC that will provide up to 22V if the source will deliver it, but 12V is a common top voltage for such applications. Some will go from 3v to 22V in .2v increments. I'm concentrating on the ability to supply 12V for the majority of QRP CW transceivers. I haven't seen a battery bank that supplies more than 12V under QC, because most QC power banks use USB-A sockets, and those are not rated for higher voltages.

The cables I bought were by JacobsParts, the same company I got my tiny Power Delivery trigger boards from only a couple of weeks ago. They also had a separate board, to which you can attach your own wire to connect it to your radio. It has a USB-A plug on the end of the board, and, like on the PD board, solder terminals for your wire. These options remove the need for a jumper cable between the power bank and the magic cable; you can connect it directly to the power bank and the other end to the radio. With the separate board, the board would plug into the power bank, and the wire would then run to the radio.

There are a LOT of power banks out there that don't support Power Delivery, but DO support Quick-Charge. These cables and boards will support QC 2.0 through QC 4.0, being forward compatible. As with PD, the power bank has to support the voltage you want, and some do not have 12 volts available, so you won't be able to use that power bank with these cables on 12v radios. If the top voltage it provides is 9v, you CAN get a 9v cable or board, and use it with a radio that will run off 9v, such as my QCX. 

So if you don't want to buy new PD power banks to take advantage of this option, check the ones you have to see if they have Qualcomm Quick-Charge at 12v. You may find that the old 10Ah power bank you bought for your phone supports QC, since it is an older protocol, and you'll be able to use it on your radios with this cable or the separate board and your own wire.

JacobsParts USB-A QC - 12v/1.5A 5.5x2.5mm coaxial plug:

UxCell 5.5x2.5mm female to 5.5x2.1mm male adapter:

JacobsParts USB-A QC - 12v/1.5A fixed voltage trigger board: (other voltages available)


  1. Hello. Just read your very interesting story about getting 12 Volts out of a power bank. Thanks! In my case, I am struggling with the same troubles. I bought an Omnicharge 20C+ but feeding my KX2 doesn't work :-( By reading your story I was looking on Amazon for the trigger board you're writing about and found something probably easier to use. But will it work? Whats your opinion about the Hilitant USB to DC boost cable Voltage converter?

    Thanks in advance!
    Greets Erwin PD3E

  2. Not the same thing. A boost voltage converter is doubling up on the boosting. The power bank has a specially designed boost converter in it on the Power Delivery standard, which is designed to reduce RF noise. A cable like the one you're looking at is a booster too, and it doesn't look like it's designed to avoid noise. You'll have birdies up and down the bands with that one.

    If you want a PD trigger cable for 12v, to go to the KX2, you'll need 5.5 mm diameter, 2.1mm aperture coaxial plug, and you'll want the other end to have a USB-C connector. That will go into the USB-C connector on the Omnicharge. I don't have the 20C+, I have the Ultimate, and it works fine. The voltage should be requested by the cable, so you shouldn't have to set anything on the power bank side, but check your manual for the Omnicharge and make sure you don't have to enable 12v on the USB-C for it to deliver it. (Seems counter-productive, as that's what the trigger circuit in the cable is supposed to do, but hey, there's weirder stuff out there.)

    Here's an example cable I found on Amazon:

    Jacobs Parts is usually reliable. I have a number of their cables and boards. Check your KX2 manual, page 5, for more information.

    Coincidentally, in your 20C+ manual, it's also page 5 that shows that it does have a USB-C control button. I suspect you might need to set the voltage for the USB-C port you intend to use. The device certainly has the right settings, it'll deliver 12V at 3A which is plenty.

    I hope you can get it working, as Omnicharge has been a good choice in my experience. But the cable I suggested should also work with other PD power banks as well.

  3. Ah, I noticed you're on the .nl Amazon site. I tried searching for the same thing there as the cable I suggested, and could only find a couple like this one:

    The only concern I have about this cable is the threaded locking nut on the coaxial plug. I don't know if it will fit on the KX2 well enough to engage with the radio's power socket. I'm not certain how deep it will have to be, as the KX2 does not have that latching connector. But that's the type of cable you want. Maybe Ebay will have one that doesn't have the locking nut?

    If you have a USB-C to USB-C cable, this device should work:

    It comes with a coaxial adapter for 5.5mm x 2.1mm, which is what the KX2 accepts. It also has the benefit of being less expensive.

  4. Hi Gwen, thanks for your answers! I allready ordered a couple of Power Delivery trigger boards. The one you described earlier. They will arrive in a couple of weeks, knowing that they will work for sure.

    I already have the adapter you are refering to, but it doesn't work.
    It's the
    Because of the wrong size I removed the dc-connector and soldered some anderson powerpoles instead. But as I said, it doesn't work.


    1. Just making sure..."doesn't work" means that the rig doesn't turn on? Do you normally run your radio from an external power supply, or from internal batteries? I don't have a KX2, so I'm unsure how that's set up. I have a KX3, and these PD devices all work fine.

      I'll experiment later today with my Omnicharge Ultimate and my own PD boards and cables and see what I come up with.

  5. The KX2 turns on with the internal battery, but it doesn't 'see' the external Omnicharge when connected. I know for sure because I can read it on the KX2 display.

    Normally the KX2 shows the amount of Volts of the internal accu, but when I connect the Omnicharge it should show the higher amount of Voltage of it on the display immediate.

    Thanks in advance for answering and helping me out!

    1. But does the KX2 operate? Can you receive and send signals?

      The circuit for determining voltage to display probably can't see past the trigger circuit. Remember, this isn't just two wires running from a 12v source to the radio, this is going through a filtered PD buck/boost circuit, the voltage and current being mitigated by the trigger circuit in the cable. The boost circuit alone would probably interfere with sensing the voltage correctly, but two abstractions, depending on how the voltage to display is determined, might simply not be able to determine it.

      I'd download the KX2's schematics and see if could figure out what it's using, such as a combined voltage divider and comparator-based sense circuit, or some other method, but even though I can rattle that off, and think I remember how that works, I don't feel I have the expertise to determine that from the schematics. I'm simply not that good with electronics.

      So does the radio operate, even though the voltage isn't shown on the display? That's the main question. Does it "turn on" like it does on internal power?

      IF not, I'd check the KX2 manual to see if the internal battery support has a menu setting that will allow it to run from internal power but NOT from external. I know my KX3 will run from external power, then pick up automatically on internal power so you see no noticeable interruption. That very thing caused a massive problem for me once, when the radio locked up while trying to update the firmware. The fix requires dropping supplied power completely, but the internal power was preventing internal power from being shut down. I wound up opening the radio and taking out the batteries to get it to finally power down all the way and reset the firmware upgrade.

      If I am feeling better soon (chronic pain from a broken neck that picked today to knock my feet out from under me and limit my functionality) I will try my Omnicharge Ultimate with my KX3.

      I just looked at the 20C+ user manual, and it's a very different beast from the Ultimate. The Omnicharge I have has an MR30 DC socket, for powering items with up to 60V. The MR30 connector is very popular with drone owners, I gather. But my Ultimate came with a short adapter cable, with MR30-M on one end and a coaxial SOCKET on the other. That way, you could set the voltage and amperage out on the MR30 port, and use a standard 5.5mm x 2.1mm jumper to go from the Ultimate to the device. The intention was to have a universal DC out that could be used, say, with older laptops that didn't have the correct USB port support. That socket could provide 20V or higher at up to 5 Amperes. But your 20C+ doesn't have it. The Ultimate also has an AC inverter, so you can plug in a device that operates on mains power. But the 20C+ doesn't have that, either.

      I'll experiment over the weekend and see what I can come up with.

  6. Hi Gwen,
    First let me wish you the best with your chronic pain, before we dive into technical less important stuff. All the best for you and a fast recovery!

    About the KX2:
    I tried a couple of thing to get things clear. First I switched on the KX2 with internal accu and saw on the display that the power was 11.9 Volts. Then I connected a 230V to 12 volt adapter (from an old internet modem) while the KX2 was still powered with the accu and saw the display changed it's Voltage to 12 Volts! So that worked.

    Then I removed the internal accu and tried to power the KX2 with the internet adapter again. That worked too.

    Next I tried to power it with the Omnirig 20C+ via usb-c, also without the internal accu. At first it powered on, but shut down after two seconds, without showing any info on the display. I don't know for sure but the reason must be that the KX2 turns itself of if the supply voltage drops below 7.5 Volts (page 136 book Fred Cady)

    Concluding overall that the Omnirig 20c+ isn't aware of the fact that it has to deliver 12 Volts Pd at 3A.

    That's why I ordered the trigger boards at AliExpress hoping that it will solve the issues. Buying another cable would be easier maybe, but I allready did and wasted my Euro's for something that doesn't work :-) So I will be very very sure before I would buy another one again.

  7. Hi Gwen, the triggerboards arrived and are working great at the moment! Thanks.