I like to travel and hike very light. I am using a QMX with a 650mAh LiPo battery, 50g. Recently I came across a charger that may be of interest to others. It’s small, 80g, and takes PD input - so if you’re traveling with a phone charger, you’re all set. The charge voltage can be set so the QMX gets its preferred 12V max. ISDT 608PD on Ali for 25 Euros.
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Given that after my last several activations my main thought is “How to make my backpack lighter”, I’m super interested in this.
So how does this work (I’m sorry if this is obvious) – the ISDT 608PD charges the LiPo battery at home, then on the summit the battery charges the QMX? And then during the hike if you want to charge the LiPo battery, you charge from your existing power bank → into the ISDT charger → into the LiPo battery?
Also, and I know I’m diverging from the topic here, how is the QMX working for you in general? How long can you operate the radio on this setup with your 650mAh battery on a single charge? My work is mostly SSB on 20 and 40 m, would that setup be good for me? I’m looking for something lighter than my ICOM-705.
Apologies for the barrage of questions 
I just got overly excited by what you showed, because I really need to reduce the weight of my backpack.
Adam EI8JEB
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I use something like this, mounted in a small case. Costs < £5
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Adam, the unit is a multi-function battery charger and it’s a lot smaller than many being used by SOTA people. Mine is 14x14x5cm requires either mains or 10-15V DC. This unit has a DC input or a USB PD input. PD is the magic expression, it means Power Delivery.
Originally USB sockets could provide 5v @500mA. Later an update to USB defined a number of extra power and battery modes and some USB sockets could provide 5V @2A . PD is a spec that lets the USB device tell the USB host what voltage and current it can use. So instead of just 5V there are high voltages such as 9, 20, 28V etc. My work laptop uses the USB C connector for charging and it tells the PSU it wants 20V at 3.3A. If you use this new battery charger with a PD capable PSU it will tell the PSU to set the right voltage. The benefit is one charger can charge your laptop / phone / electro-gizmo / battery charger. In addition, the options for LiPo etc. charging re much greater with this charger than old chargers.
At the summit, the battery (it’s Velcro’d to the radio in the picture) powers the QMX.
The advantage of this charger is its tiny so can be included in a QMX travel arrangement for not much space/weight increase. And if you already have a PD charger you’re laughing.
I have a QMX running off an Anker battery pack with a PD cable. I gave it a test over a weekend using the QMX as a WSPR beacon and it lasted about 9 hours or so each day (18-ish total over a Saturday and Sunday).
I use the same setup with my KX2 and haven’t had any issues running the KX2 at 10w with it connected. I have it as a backup to the internal battery as I don’t have the charging board for the KX2.
I haven’t used either radio for SOTA yet, but I’d happily take both, perhaps with the QMX as a backup, or run it as a beacon or run digital on it while doing CW/Voice on the KX2. I have an FT-891 as well but would sooner take the QMX and KX2 in a backpack up a summit for sure. The 891 is great for POTA, Beaches etc and you want to give it the slipper with 100w of pure Yaesu portable goodness!
QRP Labs makes a little amplifier kit for their radios that might be worth looking at if you want to give it some beans on a future SOTA. Or you can check Ali Express et al for some little amplifiers that might be good. I’ve not tried them though. I haven’t upgraded to the QMX SSB firmware yet either but reports I’ve read say it’s fairly juicy. I’ll give it a try soon enough.
It’s as Andy says, Adam. Works well a wall phone charger or a powerbank on the go. I just find it brilliant, therefore posted it here.
For me the QMX works great. I like it so much that it’s also my home shack (I admit I’m a bit extreme…). The 3S LiPo works for a quite a few hours, I have never run it to zero during my portable operations. Just in case, I typically take another 450mAh LiPo (30g) with me, but have never used it.
I am doing only CW, so can’t comment well on SSB operations. I have built a few mics for the QMX, just to prove it works well, based on the K6ARK model. With CESSB on and compression set to 7/8, the power out looks great, and the phone quality is clear and good.
As for QMX and light weight, my total setup for portable 15-60m weighs less than 500g: QMX, battery, L-match, 12.5m fishing steel wire, VK3IL paddle and headphones.
In sum, I love it. But that is just one vote, of course 
73, Peter
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Thank you @MM0FMF and @EI3LH , I’ll study your responses carefully later today and surely ask more questions, but for now just curious if, after buying QMX, the above charger gives me any benefit above the SmallRig 99 which I already have (for photography purposes). That SmallRig gives 3A to 12V and 3A to 8V (barrel-type sockets), has USB-C up to 20V (3A) and D-Tap (up to 15V at 14A). It has 6.7Ah nominal capacity.
It is quite bulky (see image compared to ICOM-705) but since that combines charger + battery, I wonder if that could be my only power source for my hikes – for QMX, phone, camera, etc.
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I also have these Digicam batteries that Zi have been looking to as kfo use for my QRP radios
Initial testing has been positive and I can attach it to the Peovi cage very easily
John ve3ips
Thank you @HB9EBE . Looks like I’ll definitely give QMX a try. I think I’ll go for this option:
- 80/60/40/30/20
- 12V
I just need to make sure it works reliably on SSB (I don’t know CW yet), and need to figure out reliable way of powering it… which is what this thread is about. I may need to keep it powered for longer, as I will definitely be on hikes that cover 2 or more summits.
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That appears to weigh 580g compared to 50g for the 650mAh LiPo battery. If you are carrying it anyway for your photography then it might be reasonable (except for eggs in one basket) but otherwise it’s a bit heavy.
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My understanding is @HB9EBE has 50g of the LiPo battery + 80g of charger + xxx grams of a powerbank, which brings the weight closer to SmallRig if it was to be the only thing I take. But I agree, it is quite heavy, I’m just reviewing the options here…
You only need to take the 50g battery to the SOTA summit. You have the 80g charger plus USB PD power supply back in your hotel room.
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As Richard says. I only take the 50g to the summit, may take another 50g Lipo for safety.
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Okay, got it now. That is indeed a significant difference. I want to travel this light, so yes, I’ll be looking into buying QMX + a battery (plus one for backup).
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I’ve re-read all the responses again. Very interesting. So you’re saying @HB9EBE Peter that QMX + 3S LiPo gives you a few hours of operation? That’s a lot with this small setup! And being able to bring down the weight of the whole HF radio setup to <500g… wow, I’d love that.
Okay, off to ordering QMX to give it a try… I suppose SSB which I do won’t be much more power hungry than CW, so I should be good.
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I have found this transformer, from USB to LiPo S3, even lighter on 4M4Z0N as “cables de carga USB de batería LIPO con conector XH-4P para Airsoft RC Car Drone Boats”. It does balanced charging
73, Mikel
I have tried those as well. Their charging isn’t very balanced and the LiPo deteriorates over time. But nice to carry for emergencies.
I used one of these for years to charge my KX2 battery (3S 18650) while traveling. I did have to add a balance lead to my battery pack, but it worked very well. It charges at a low rate, so to recharge my KX2 battery after a couple of activations was an overnight operation. I also cut some vents into the plastic case because the thing would get very hot. I didn’t notice any problem with the balance or that it caused the battery to degrade.
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