Constructing a Backpack VHF Field Radio, by Ed S.

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Constructing a Backpack VHF Field Radio, by Ed S.

Much has been written about life after TEOTWAWKI. Looking at all the different scenarios leaves one thinking that,with so many things that could happen, how can you prepare for all of them? Obviously, you cannot. However, many of the preparations we make can be used across the spectrum of possibilities. One thing that groups need to be able to do is keep in contact with each other. Small hand-held radios, or “walkie-talkies” work for most needs but are limited by range and crowded bandwidth. Both the GMRS and FRS systems are in use 24 hrs a day and, since they are relatively cheap and easy to obtain, you can count on them being heavily in use after most any event. Citizen’s Band (CB) radios while limited in range, will face the same problems. [JWR Adds: Using a crowded band will decrease your chances of making a successful contact and increase the chances of unintended interception. For this reason, I recommend using lightly-used bands, such as the MURS band.]

One area that is most always overlooked is Marine Band VHF radios. Since the FCC requires these to be used only on vessels actually on the water, few people are familiar with them outside the Marine work and pleasure fields. They have many positive traits that can be utilized in the event of a TEOTWAWKI. For that an event that is that serious, I feel the FCC restrictions can be overlooked.

The Marine Band base units are 12 volt DC, they offer a choice of 25/1 watts of transmit power and are usually small, lightweight and sealed against harsh elements. The handhelds (walkie-talkies) are also small, rechargeable, offer a 5/1 watt option and are also weather sealed. An average base unit can be had for around $100 to $120 and the handhelds can be had at most any boating or sporting goods dept for about $55 to $90. That makes them relatively affordable.

Using an attached small boat base antenna, in the described setup we have achieved 20+ mile range. Here is what you do:

Materials:

  1. A military surplus large ALICE pack.
  2. Your choice of base station set.
  3. A small boat or so-called “sailboat” base loaded whip antenna,
  4. A piece of marine grade treated plywood, sized to fit the inside dimensions of the pack you choose (we use ALICE packs for their durability, but any sturdy pack [with a stiff frame] will do.),
  5. A small 12 volt battery of at least seven Amp hours. (We use the [gel cell] batteries sold at places like Wal-Mart in the toy dept used to power the kids electric cars and such.),
  6. Coaxial cable for the connections.
  7. A DC power cable of at least 10 Gauge.

Assembly:

  1. Connect to the pack board your radio at one side of the top and your antenna on the other so it protrudes out of the pack as high as possible using three wing nut screws. (The sailboat rig that I purchased comes with a L-Bracket that is perfect.)
  2. Next mount your battery in the middle at the bottom to balance the weight.
  3. Connect to your battery another set of power leads and run them out the bottom of the pack for recharging.You can also add a one or two pigtail “cigarette lighter plugs” [or Anderson Power Pole connectors], for an easy 12 volt source to power other items from your battery,such as a powerful spotlight, charger for other items etc.
  4. Check your connections and you are ready to patrol your perimeter, travel to visit other groups, set up LP/OP sites, and most anything that you feel the need to do that causes you to leave your camp.

Conclusion:
We have had luck with this set-up as it also allows your party to send out scouts, et cetera with handhelds because it gives them more range also. At your night camp or break, using the wing nut attachment system, the antenna can be dismounted and moved to a tree, structure, or high bush for more range if needed, since VHF is line-of-sight.

Other items can be attached to the board, as your situation calls for, such as a small scanner or a CB. You are limited in this only by the weight and space factors.

JWR Adds: The foregoing is presented for educational purposes only. Operating a Marine Band radio in circumstances not permitted by law is subject to some very hefty fines!

Be sure to properly insulate any exposed power terminals. Shorted terminals can result in some spectacular unintentional arc welding for a few moments! A large glob of RTV silicone sealant on each terminal usually works well.

Adding a five to 15 watt amorphous (foldable) photovoltaic panel and a compact charge controller to the rig that Ed described will provide greater flexibility and self-sufficiency.