Field Day – 200 QSOs with a Flashlight Battery

Field Day was an experiment this year. I ran my operation for nine hours using a 5V 18650 battery. I made 200 QSOs before calling it quits.

I operated on the deck with an MTR 4-B designed by KD1JV. The antenna was an 88 foot doublet up about 45 feet. I used the ZM-2 tuner. For power I used the Powerfilm Lightsaver. This is a 5 watt roll-up solar panel that charges a 3.7V 18650 battery rated at 3.2 Ahr. The battery inside the Powerfilm product is commonly used in flashlights. The combination of the rig and the power supply is crucial.

The MTR rigs will operate from 6 to 12 volts. The Powerfilm puts out 5V to a USB socket. The secret ingredient required to bring the USB voltage up to the operating voltage of the rig is a Baofeng USB charging dongle. This device takes a 5V input and outputs 10.3 volts… perfect for the MTR transceiver. With this voltage the MTR puts out a little less than 3 watts.

The Powerfilm Lightsaver is designed to charge cell phones for hikers and campers. It weighs only about 5 oz. and rolls up into a tiny package. Any USB 5V cell phone charging battery could be used with the Baofeng dongle.

This year my whole station operated on 5V. I used a Samsung tablet for logging.

In New Hampshire it was cloudy for most of Field Day, but fortunately the amorphous solar panel provides some charging even when it’s cloudy. I’m guessing that after 9 hours of operating the battery was down to about half capacity. The beauty of this system is that one could operate indefinitely with moderate sunshine.

I’ve been experimenting with this setup during hikes and bike rides for the last couple of months with a view to using it for Field Day. This year’s emergency exercise proves that it is viable for an extended grid-down power outage.

Jim Cluett, W1PID, is a regular contributor to and writes from New Hampshire, USA. Contact him at [email protected].

7 Responses to “Field Day – 200 QSOs with a Flashlight Battery”

  • Richard KWØU:

    Now that is impressive. What mode and frequency were you operating on? And how far away were you able to contact people?

  • bob.c k1qed:

    Jim, an outstanding example of emergency operation! I’d call this “proof of concept” for sure. I’ll bet the whole station comes in at a pound or less. FB!!!

  • Thanks for the note. I operated on 80, 40 and 20 CW. I remember
    working California, and AZ and a couple of Europeans.

  • Thanks for the note. I usually use this station in a small
    backpack for hiking. It’s pretty light, but I never weighed it.

  • Bill K8TE:

    Your antenna was better than many home antennas in use today, Jim. It and CW were the key. I operated 21.5 hours, K4, OCF 80m dipole at 40 ft. All 1,710 (plus 80 dupes) but four 2m contacts were on CW. 20m was the money band from NM although I did make many on 40m and some on all the others. Your station would be great for SOTA.

    73, Bill, K8TE

  • Bill – Thanks for the note. Yup, antennas are the secret.
    Wow… What an awesome total you had! Congrats OM. 73 Jim

  • Barry Bogart, VE7VIE:

    Thanks. I just ordered that Baofeng device. BTW Home Depot sells solar garden spotlights that use these batteries. I’ve been running one for a year, meaning to get to a radio application.

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