A very effective video of HF portable ham radio, filmed in the Arctic with wood fires, snow, and ice all around. Quite a good argument for the modular raspberry pi computer and accessories as the go bag unit, too. It shows how the use of weak signal HF messaging/ HF networking like JS8call is changing the realm of possibilities for operators. QRP-level text networking communication combined with positioning and selective calling is a powerful combination.
Thanks Bonnie. It sounds so much better when you put it like that. There's still a lot of work to do. This field test was definitely a successful proof-of-concept. Now I need to do two more things. First a solar generator for the 817/818, a small one. One which fits perfectly under the rig, and is secured there with industrial velcro. After that, I'll turn my attention to an enclosure for the entire kit. I've ordered some leather for that. The goal is making a form fitting leather case, with a flap for front panel access to the radio. If this can be pulled off, it'll look like the integrated Comms kit I'm trying to achieve. I'll do this for the 891 as well. This will protect the wires between the radio, Raspberry Pi and 10 watt amplifier. It'll be less protection than the Pelican case, but it'll also be lighter and more portable. I can always put it in a dry bag. It's always awesome to get your feedback. It's like a motivation bomb to keep moving forward. 73 Julian oh8stn
The goal is always to make something interesting to a wider audience. Your comment was the best compliment you could have given. Thanks for that. 73 Julian oh8stn
The Rpi can suffer corruption when its power is interrupted. With its external power supply connections, what measures do you take to preclude power interrupt to the Rpi?
That's true. I addressed this in the first video from this series, but can explain here briefly. Firstly I'm suggesting we don't use the standard USB connector to power the Raspberry Pi. It's prone to being pulled out inadvertently, leading to the very thing you mentioned in your comment, card corruption. To rather than using that USB connector, we tap the 5 volts and ground pins from the headers, routing them through an RF quiet buck converter. From the buck converter, wires snake out of the rear of the raspberry pi, terminating with Anderson powerpoles. Next there is a soft button connected to the pin headers, telling the raspberry pi to shut down nicely. It will close all running applications, and shut down the Raspberry Pi. A few seconds after pushing that button, power to the Raspberry Pi can be removed. The next time power is applied to the DC input, the Raspberry Pi will start up automatically. That's how it's set up a my system right now. Now because I'm kind of a redundancy not, I also carry an identical copy of the SD card running on the Raspberry Pi. In the unlikely event the SD card is corrupted, I can replace the Raspberry Pi SD card in seconds, getting right back on the air. I'm also experimenting with a device called the PiJuice hat. It's a ups for the Raspberry Pi. It has its own power source, and detects when powers to the Raspberry Pi has been removed. It will close all apps running on the Raspberry Pi, shutting the Raspberry Pi down correctly, even if external power is abruptly removed. Great question. 73 Julian oh8stn
Have a look at Hardened Power Systems. I had a QRP Ranger with Solar, with an 817. it was a perfect portable kit. Keith and the crew at Hardened Power are always coming up with great gear. Sometimes you have to wait for stock, and shipping, but the gear quality, and customer service is amazing. check them out! portableuniversalpower dot com /our-products/qrp-ranger/
Thanks for the comment. I know HPS very well, having made the mistake of recommending them on the channel once before. HPS made excellent equipment for lead acid batteries and perhaps still does. Their first gen attempts into Lithium Iron Phosphate chemisty were a complete fail. No internal battery management system, cheap and unbalanced/unmatched chinese cells held together with hot-glue, RF noise, and poorly designed 3D printed enclosure were all enough reasons to put people off. Since then they are integrating Dakota Lithium cells in some of their gear. That was a good move for a company lacking lithium ion and lithium iron phosphate expertise in-house. This only leaves justification for the price. A good small capacity Dakota lithium pack comes in at around 100 bucks (starting) which is reasonable. Add an enclosure, chinese charge controller, some wire, switches, relays, most of which sourced from China ... and the HPS price is what it is. Personally, If I couldn't figure out how to build my on pack using many of the free online DIY Ham Radio portable power resources, I would just buy the Dakota Lithium pack, and put it inside a pelican case using my own switches, wires, fuse, relays, ... When one builds diy taking control of design, componet quality and component specification choices, it becomes impossible to justify the HPS price. HPS has beautiful gear, but they don't build reliable gear. Its not their fault though. Everyone is trying to compete with the Chinese invasion. Some compete through quality, others through higher price. 73 Julian oh8stn
Julian, a great post, as usual. One question: can you please tell us which model GPS module you plug into the Raspi's USB port? Thanks.
You are very welcome. It's a standard vk-172 ublox gps from Amazon, eBay, ... all the details and configuration instructions in this video. 73 Julian oh8stn
Julian, I love watching your video's, especially the ones in forrests and snow. I just love Scandinavia and its rugged environment! I was wondering if you ever experimented with battery packs without BMS. And I mean the types of BMS that balance the cells. I am currently setting up a PV and battery system for my off grid summer cabin (in the Netherlands, unfortunately) and I am planning to use a 12.8V LiFePO4 battery pack without BMS system, only using the low cut-off protection in the inverter for 230V loads and a Battery Protector (all Victron stuff, by the way) for 12V loads. The idea is to bottom-balance the cells all in parallel (discharge them to 2.5V), then connecting them in series and "be done with it". I will let the solar charger cut off at 3.55VPC and, of course, regularly check each cell voltage. And when designing this system, I thought about doing the same with my Yaesu FT-897D: throw out the NiMH battery packs and fill that space with LiFePO4 cells without BMS but use bottom-balanced cells. Theoretically I should be able to keep the cells connected to the 12V power supply input, ensuring my shack's PSU outputs no more than the float voltage of the 4 cells in series (3.3VPC). Any ideas about this? 73, Meindert PAøMHS
Another great quesiton. Yes I have, but won't ever show it on the channel. With the battery tutorials, I have found many operators can't won't follow instructions. Even worse, they don't do period checks to insure cells remain within spec and have an even discharge rate. The 20ah pack from my most recent video has no BMS. It was bottom balanced, but also has an active fail safe, which keeps the cells within ˜0.2v of each other. The active circuit transfer energy from higher voltage cells, to lower voltage at 1amp rate. Doesn't resitance bleed like traditional BMS. My shunt controls LVD through relays, while the Genason controller, mananges charge rate and prevents over-charge. It is very similar to your Victron system. These type of systems should not be ones first project imho. However, they can be very reliable and outlast/outperform any lead acid system. Initial cost is higher, but it will last forever. I left out the BMS from the 2+ah ld because of space restrictions. A good BMS (not the fake marked Chinese crap) can be a fail safe for your investment. You'll have to consider why you're leaving it out. Short circuit protection is a critical feature being left out of your system. Just saying Most Victron systems can be switched of for LiFePO4 chemistry. There is no need to run it on <lead Acid settings,. LiFePO4 don't need a float charge or any of the lead acid nonsense. So do your reading before you choose. I'm hoping to completely rebuilt the shack with Victron gear. It's nice to hear other are too. 73 Julian oh8stn
Julian, thanks for you exhaustive answer. I know the problem of users not following instructions. I run a small company and I design marine electronics (NMEA 0183 multiplexers and 0183/2000 gateways). I get indeed a lot of questions that could be found in my manuals. I always say: men don't read manuals. Yet those same men always complain that their wives don't come with a manual... ;-) This is indeed my first LiFePO4 setup but as I said, I'm an electronics engineer, know my sh*t and read about everything there is to find about BMS's and LiFePO4 batteries and their quirks. But I'm glad to hear some first hand experience from a "small battery" user. I had a lot of good tips from a ham on this forum who is very experienced in off-grid installations an EV's using those LiFePO4 batteries without any form of BMS. Just bottom balanced packs, decent LV and HV cutouts and regular checking of cell voltages, which I also intend to do. 73, Meindert PAøMHS
