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2 Days Off Grid with PowerFilm, Ham Radio and a Raspberry Pi

Discussion in 'Amateur Radio News' started by OH8STN, Jun 9, 2018.

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  1. OH8STN

    OH8STN Ham Member QRZ Page

    Hello Operators
    Topic of the day is off grid solar and battery power for ham radio and our Raspberry Pi.
    During March 2018 I took a short trip to 66 degrees North, to field test the solar powered ham radio field station. I had the 120 watt PowerFilm solar panel, the Yaesu FT-891, and a Raspberry Pi running WSJT-X and FLDigi. The entire station ran off grid for the 2 day excursion, completely powering itself, despite operating QRO, which I don't normally do out in the field. I suppose the goal was to finally throw caution to the wind, just get out there to see what happens.

    In this video we discuss off grid, man portable and pack-able power. We also discuss the PowerFilm FM16-7200 120 watt folding solar panel, measuring its performance and ability to power the QRO field station. Finally, we discuss integration of the Raspberry Pi 3B+ into the field station, and address some mods to reduce its shortcomings.
    Julian oh8stn

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  2. KQ6XA

    KQ6XA Ham Member QRZ Page

    As an avid HFpack operator, I've gotta say, that Julian's station in this video looks like a lot of fun to put together and operate!

    That's an impressive strategy for a backpackable HF 100W field unit, with the large fold up solar panel and modern Lithium battery system.

    It is proof that we need not be limited to low power in the field anymore; especially important during poor propagation conditions.

    Using the "local remoted" tiny Raspberry-Pi computer for digital modes and rig control, with that small on-board battery backup is a brilliant solution.

    The video: Fabulous scenery in the forest clearing where Julian set up his station.
    Julian's signature voice-over narration work is informative, descriptive, and documentary-quality.

    I subscribed to the OH8STN youtube channel... which is high praise, since I rarely subscribe to anything on youtube.

    and I just added the OH8STN blog to my favorites. Julian's blog is an excellent reference for cutting edge lightweight HF station tech, and it dives deeper into some of the stuff on those videos.

    OH8STN has really become a prime source of inspiration for modern HF field comm techniques.

    Screen capture of the OH8STN youtube channel:


    Screen capture of the OH8STN.ORG blog:


    -Bonnie KQ6XA
    Last edited: Jun 10, 2018
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  3. OH8STN

    OH8STN Ham Member QRZ Page

    You're too kind Bonnie.
    There is so much more to learn and share.
    Julian oh8stn
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  4. WA2LXB

    WA2LXB XML Subscriber QRZ Page

    Great video, thanks.

    That solar panel is $1,200, so let me ask a few questions:

    • What was your average current consumption during QRO operations?
    • What was your average transmit power?
    • Did you operate at night, and did you carry a tent and camp gear?
    • What was the weight of your kit, all-in including backpack, food, water, tent, etc.?
    • Do you think you could have used a smaller panel for 48 hours of operations? If so, how much smaller...maybe 60 watts instead of 120 watts?
    • What antenna did you use?

    I've installed my IC7300 into a PortableZero backpack, and everything for QRO operation including a 20AH Bioenno LiFePo fits with room to spare-with no solar panels yet-but considering two of these. If I'm going to add tent, food, and water I'll strap that pack to an Eberlestock external frame pack.

    Thanks for the details...they matter.

    Hugh WA2LXB
    Last edited: Jun 11, 2018
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  5. KQ6XA

    KQ6XA Ham Member QRZ Page

    annual_solar_insolation.png solar_insolation_date.png
    Hi Hugh,

    Considering Julian's arctic circle location, he needs roughly twice the solar panel rated capacity than we do in continental USA.
    It also depends a lot on cloud cover and sun exposure time (length of day).
    When I was operating on expeditions close to the equator (Borneo and Peru) I was amazed at the "improved output" of my solar panel, compared to California.
    Using the same solar panel, in the arctic circle it would have about 40% of the solar power we would get compared to the equator.
    The greater thickness of the atmosphere at higher latitudes, due to lower angle of sun, attenuates the sun's rays.

    -Bonnie KQ6XA

    The peak energy received at different latitudes changes throughout the year. This graph shows how the solar energy received at local noon each day of the year changes with latitude. At the equator (gray line), the peak energy changes very little throughout the year. At high northern (blue lines) and southern (green) latitudes, the seasonal change is extreme. (NASA illustration by Robert Simmon.)


    The total energy received each day at the top of the atmosphere depends on latitude. The highest daily amounts of incoming energy (pale pink) occur at high latitudes in summer, when days are long, rather than at the equator. In winter, some polar latitudes receive no light at all (black). The Southern Hemisphere receives more energy during December (southern summer) than the Northern Hemisphere does in June (northern summer) because Earth’s orbit is not a perfect circle and Earth is slightly closer to the Sun during that part of its orbit. Total energy received ranges from 0 (during polar winter) to about 50 (during polar summer) megajoules per square meter per day.
    Last edited: Jun 11, 2018
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  6. OH8STN

    OH8STN Ham Member QRZ Page

    • What was your average current consumption during QRO operations? Great question but impossible to answer accurately. I didn't have the meter inline all the time. Next time out, I'll measure both incoming and outgoing current and give that answer.
    • What was your average transmit power? 75 watts.
    • Did you operate at night, and did you carry a tent and camp gear? I carried my Nortent Tipi 6, a yoga mat, JetBoil, 2 liters of water, dehydrated jambalaya, ... I would have used my Halti expedition pack but the weight didn't justify it. I was perfectly comfortable in this pack, so I didn't measure pack weight. I only cared if I could move effectively with the weight in the pack. I didnt operate at night.
    • What was the weight of your kit, all-in including backpack, food, water, tent, etc.? Redundant question.
    • Do you think you could have used a smaller panel for 48 hours of operations? If so, how much smaller...maybe 60 watts instead of 120 watts? Actually it's funny you mention 60 watts. I definitely think a 60 watt panel would have done the job and probably have been a better gear choice. I chose the 120 because I live so far north it's ridiculous. Choosing the 120 was a "better to have it and not need it, than to need it and not have it" choice. In hindsight, two 60 watt panels would have been a wiser choice. For the record I'm not promoting that panel, the video is simply showing what I used.
    • What antenna did you use? I used two different antennas during the weekend. In fact, antenna testing was the secondary reason for being in the field. I had a PackTenna Mini 9:1 random wire , and Chameleon EMCOMM 3 Portable, also a random wire. I didn't finish those tests, but I will next time out during July with videos to follow.
    It's important to point out this is a series. This first one was just a test to see is it possible, what are the logistics, how it's going to work out, ... it's nothing I haven't done before, but the challenge is documenting it all. The only thing I'm missing now, is my hiking trailer. My previous one isn't up to it. That may very well be the MonoWalker, but let's see. I have planned for 4 excursions during July. Then repeat during winter. The series is called "X Days Off Grid with (insert gear & goals)".

    Julian oh8stn
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  7. WA2LXB

    WA2LXB XML Subscriber QRZ Page

    Thanks Bonnie and Julian. I hadn't even thought about the reduced sunlight at Julian's general location, as my brain saw "sunny spot" and "northern woods" and didn't think at all about latitude because the area in the video looks similar to my QTH.

    After the ARRL Field Day this year I'll continue to develop my pack-portable gear. I appreciate the tent and antenna references. Please let us know how you like the two antennas, especially the EMCOMM 3 in its various configurations. Hopefully empirical testing will show that it's as advertised...a flexible antenna system if you keep a cheat sheet handy for how it needs to be deployed for various capabilities...from NVIS to DX.

    I want to develop an ultra light weight 160-6 OCF or Carolina Windom for 150watts PEP max. I'm working with a friend to model it, but we are just getting started with EZNEC.

    73, Hugh WA2LXB
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  8. KB9RDS

    KB9RDS XML Subscriber QRZ Page

    Maybe i missed something but here goes. This setup may be good for off grid fun in the field but if you use wsjt it seams worthless for Emcomm and you can not pass critical traffic using wsjt. So why do you state use in Emcomm, i do not understand this concept. Only thinking of Emcomm. My home station is 100% solar and i can and have passed traffic. What are the limits on your station using SSB or Winlink etc. Just mine and a general thought.

    Steve Wendt USN (Ret)
    Indianapolis, IN
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  9. KC8VWM

    KC8VWM Ham Member QRZ Page

    Unless you can get the 160m antenna high enough above the ground, it will just function like it's laying on the ground even when it's installed at a height of 30'.

    An inverted L and large tophat verticals are much better choices for this band.

    160m is a bit of a challenge for most portable setup operations. I have a portable wire dipole reel antenna that gets me down to 80m, but quite frankly I rarely operate on that band while portable.


    Most of the time I only need an antenna to operate on the "daytime bands" while portable anyways. Usually 10m - 20m is quite sufficient. 40m being a band used later in the evening while sitting by the campfire sort of thing.

    In terms of solar power, I have around 85 watts I can take along...


    I am using much cheaper "CIGS solar panel technology" which is mil spec. and made for the U.S. military by the Global Solar Corporation. They work perfectly fine as an alternative to the much more expensive PowerFilm panels.

    folding panel.jpg

    You can get them here:

    I'm also using the same Genasun controller Julian is using and quite frankly, it's highly recommended.

    These controllers are FCC certified and they generate no RF noise in your radio receiver unlike many other cheap solar panel controllers on the market do.

    These are also true MPPT charge controllers which put more energy into your battery when measured on a power curve chart over a day of charging. So what this means is they work to maximize your solar panel charging capabilities even during cloudy overcast and low light conditions. Well worth the cost considering the idea they actually help to increase your solar panel output capabilities!


    Always enjoy watching Julian's videos and what he's doing with portable off grid radio operation. Seems like Julian is doing all the hard work testing everything so we don't have to. :) Always looking forward to watching his videos for some great helpful tips!

    Thanks for another great video Julian!
    Last edited: Jun 11, 2018
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  10. OH8STN

    OH8STN Ham Member QRZ Page

    Steve, this was a field test! The only limitation with the setup is ones imagination. WSJTX w<s shown in the video, since I used it for Anttenna testing (secondary reasons I was out there). The Raspberry Pi can run FLDigi, PAT Winlink, FSQ, FT8CALL, APRS, as well as all the other modes FLDigi offers. If you're searching for something, It does not play well with WIndows (thanks goodness)-
    Your station is 100% solar and can and has passed traffic. This station is man pack-able, completely self sustained, and can do most things your home station can. One thing your home station can't do it be carried 30 clicks into the foothills.
    Julian oh8stn

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