June 4, 2016

Backpacking Amateur Radio Power: Requirements

So how do you bring an iPhone and HT on a backpacking trip and use them without running out of battery before the end of the trip?  In this post, we explore this question and the related requirements.

We have been doing a lot of backpacking lately in the mountains of Northern California.  Backpacking is great exercise, physically challenging, and a great way to immerse yourself in nature.  A backpacker must carry everything needed for the trek including food, water, shelter, clothing, first aid, and personal items.  Our 3-day/2-night pack weighed in around 30 lbs / 13.6 Kg.  Weight comes at a big cost to a backpacker, so the objective is to minimize.

When trekking in the backcountry there is often no mobile phone coverage.  Mountain peaks sometimes provide a line of sight to a faraway cell tower which can yield one or two bars of signal.  In our experience, the valleys are barren of mobile phone signal.  We still carry our cell phones on backpacking trips because the phone provides a good camera and can also serve as a potential emergency communication device.  Being able to summon help when you need it most is invaluable.

Amateur radio VHF/UHF repeater coverage in the backcountry is more readily available than cell phone coverage in the places we have been hiking.  This makes the amateur VHF/UHF HT a valuable companion on a backpacking trip.  In an emergency situation, communication can make a tremendous difference in the outcome.

We programmed our Kenwood TH-F6A tribander radios with as many repeaters as we could covering the areas we like to travel and backpack in Northern California.  The TH-F6A transmits 5W on the 144 MHz, 220 MHz, and 440 MHz amateur bands. We also programmed them with the various simplex calling frequencies.  We bring them on every trip.  Sometimes we also use our TH-F6A with our TinyTrak4 TNC and GPS for APRS tracking.  The TH-F6A has a wide-band receiver which allows us to listen to broadcast radio in camp (AM/FM).

Kenwood TH-F6A hand held transceiver
Kenwood TH-F6A Triband VHF/UHF HT is perfect for backpacking

The challenge with bringing electronic devices on a backpacking trip is using them without running out of power before the trip ends.  We don't simply want to throw the devices into our packs powered off during the trip in order to save the battery.  So what are the requirements for the solution?  We defined our requirements in the form of a user story with acceptance criteria:

USER STORY: As a backpacker, I need a way to use my TH-F6A radio and iPhone 6 during my backpacking trip and not run out of battery before the end of the trip so that I can have fun with the devices during the trip and have them ready for use at any time during the trip in the event of an emergency to call for help.

  • Must allow the backpacker to use the device a little or a lot as needed.
  • Must be flexible enough to allow the backpacker to use the solution regardless of duration (our typical backpacking adventures range from from 1 night to 15 days).
  • Must not add significant weight to the pack (< 1.5 lbs/0.68Kg).
  • Must be able to maintain power for an iPhone via the USB connection (5Vdc USB power).
  • Must be able to maintain power for a Kenwood TH-F6A via the 12Vdc connection.

Now that we understand our requirements, we are ready to explore potential solutions in the next article.

Good DX and 73, NJ2X

Articles in this series:

© Michael W. Maher and NJ2X.COM, 2016. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Michael W. Maher and NJ2X.COM with appropriate and specific direction to the original content.

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