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)

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