On October 18, 2019 I published an article TEOTWAWKI – Comms Challenge and many of you chose to play and for that I thank you. Now is the time to put forth an answer to the challenge which I will attempt to answer using by bag of tricks and some suggestions from those who participated in the challenge.
A catastrophe has happened in your AO so devastating the only thing that survived was some other humans and one of your transceivers. No shelter, no electricity, no food…You get the idea. Since communication is vital for survival after you take care of water, food, and shelter; describe how will you get that one transceiver ready to send (TX) and receive (RX) communications.
Let’s get started
Power will be your first concern and with a bunch of useless vehicles laying about that means a bunch of 12-volt batteries are ripe for the taking. As most of the readers know, most transceivers use 12-volt power to operate. Transceivers typically work best around 13.8-volts however you will be able to easily get by with 12-volt batteries down to let’s say 11.8-volts. Also keep in mind that receiving (RX) takes far less power than transmitting (TX). You can put those batteries in parallel which would give you a deeper power source not unlike having a 35-gallon truck fuel tank vs. a 15-gallon car fuel tank.
To keep the batteries charged, I loved Matt in Oklahoma’s idea of borrowing solar panels that keep batteries topped off that powers state and local municipalities signs.
Regardless of the devastation there will be wire lying about. Heck there may even be coax and ladder line about from TV installations available. I would start out making a ground wave antenna to receive communications. Below is a simple ground wave antenna that I wrote about is a previous article, Your Comms In A Grid Down World. Grab six non conductive poles 2-inches width and about 4-feet long. Tree branches would work too; pound into the ground in a square configuration, hang the wire on the poles with the two bitter ends going back to your transceiver. One wire can go into the center of the chassis SO 239 of your rig and one wire can be attached to the outside (Threaded) SO 239. Viola! You can now scan the bands listening for information. This serves two purposes. 1) You can get immediate information, and 2) You know what frequency to cut your TX antenna too.
For kicks & giggles I am going to assume your transceivers will not have a built in tuner. The best way to set up to TX without a tuner would be to cut your antenna wire to band length. Remember that the different bands, 10, 12, 15, 17, 20-meters et cetera are just that. For this exercise I will pick one out for building an antenna. I heard a lot of communication on 20-meters using my ground wave antenna. So that is the band I will start with. 20-meters x 39 inches = 780 inches then divide that by 12 (Feet) and the wire length you need is 65-feet (32 1/2-feet per side of the dipole antenna) plus 2-feet or so for the ends of your antenna. If space is an issue you can use half that length or 32 ½ feet. Divide this length in half and each side of your ½ƛ (half-wave) 20-meter antenna will be 16 feet 3 inches plus 1-foot for attaching and trimming if necessary. Now you need a non-conductive center for the two wires. I would look for a piece of PVC pipe. Saw, burn, et cetera a length of 3 to 4-inches or so and drill holes at both ends for the antenna wire to pass through. Drill a hole in the top to use for a suspension point and in the middle on the bottom 2 additional holes about 1-inch apart for your coax or ladder line to pass through.
With that done you could use the scavenged TV coax or ladder line to bring the signal down to your transceiver. If you do not have the scavenged TV coax or ladder line, no worries, you can build your own ladder line. Let’s go with the TV coax and or ladder line first.
Put the 17 feet 3 inch (16-feet 3-inches plus 1-foot for wrapping) hank of wire through the two pre-drilled ends of the PVC pipe and stretch out on the ground then through the two center pre-drilled holes feed the center of the TV coax to one of the wires and the braid to the other. Similarly, with the ladder line feed one of the wires to one of the wires and the other to other wire. Put up the now completed antenna in a inverted “V” configuration as high as you can get it. Anywhere between 16 (1/4ƛ) to 32 feet (1/2ƛ). Tie off the two wire bitter ends at a approximate 45-degree angle from the center (90 degrees total). Once done put the center wire from your coax into the center of your radios chassis SO 239 connector and the braid to the outside (Threaded). Fire up your radio and start communicating.
No TV coax or ladder line available, build your own ladder line. You will need two pieces of wire (insulated would be best) 41-feet long and 90 or so 1/4 to ½-inch in diameter and 6-inches long wood or plastic ladder steps. Fasten the ladder steps every ~5.33 inches while keeping the wire separated at a constant of ~5-inches. When the antenna is hung, do not let the ladder line touch the ground. It is Okay if the ladder line looks like a serpentine to your transceiver though. Again, put one of the bitter ends of your ladder line in the center of your radios chassis SO 239 and the other on the outside (Threaded).
If you have a mic great! Go for voice but if you do not have a mic build a CW key. I have never done this however, here is a great home brew CW Keyer by Sarasota Emergency Radio Club called a Hackey.
This is what I would do in a pinch if I was left with just a transceiver post a catastrophe.
Freedom Through Self-Reliance®