(7 January 2016, 15:46)Tartar Horde Wrote: These threads have been fascinating and I understand the importance of good comms during any shtf scenario but admittedly I still remain a tad confused. In a power outage would these sytems still work?
My ideal unit would be handheld, capable of twenty to thirty mile send and receive with the ability to charge by solar if no mains leccy, does anything exist with those specs, plus no licence to operate, but in a shtf I don't care about licences.
Hi TH. Good that you know what you do not know, so to speak.
Radio communications without mains power: The first criteria of the radio systems I have discussed here is they continue to function in an electrical grid down situation. These devices are intended for use after the mobile and fixed line telephone systems have failed as well.
This particular solution can be powered from anything from 9v to 13v. In the real world this means that usunf one of the little oblong PP9 batteries, or 12v from your Solar cell charge regulator, or a car battery etc.
Now it gets more complicated.
A handheld with a 20 to thirty mile range is not just something you want, its something that everyone wants. And in that criteria we all want to be able to talk to everything at all distances out to that maximum range as well. Such a solution only exists in the minds of film makers and novelists.
I have achieved totally reliable communications by handheld radio over more than 50 miles. My 4 watt handheld UV5r when attached to a wire that disappears up the side of the chimney of my house can reliably reach radio repeater more than 60 miles away. Both of these examples are rare exceptions to the rule.
And the rule is, that generally speaking, for a handheld walkie-talkie radios do not expect more than 3 to 5 miles range, and in the case of license free PMR446 radios expect the range to be from hundreds of meters to a maximum of 3 miles. The reason is that this sort of radio generally operate on frequencies that almost only travel as far as you can see ( literally, if you can see it your signal can reach it) and when the transmitted radio waves reach the horizon the carry straight out of our atmosphere into space.
The kind of radios used by radio amateurs, military etc can also produce frequencies that behave differently. At the special ( lower frequencies) the transmitted radio waves get reflected back to earth from the higher levels of the atmosphere. This extends the range of this type of radio significantly. In fact on the right frequencies and at the right moments in time the range of these radios is global. These radios can perform this longer and ultra long range communication at relatively low power. Again all of the radios that I am discussing on the SUK site can be powered from 12v or less power sources.
Sounds too good to be true? Well there is a snag, and it comes in the form of the antennas needed. While handheld radios have antennas up to say 1ft long, the antennas needed for over horizon communication are much longer, in the region of 15 to 120 feet long in fact. These antennas can be scaled down to the size of CB radio whip antennas, but that scaling down adversely affects efficiency both of receiving and transmitting. So a scaled down antenna hears less and requires significantly more power to perform its task.
On the face of it CB radios, and in particular SSB models most closely match your requirement (SSB = Single Side Band which is a MODE of transmission, as are FM and AM with which you will be more familiar) These radios have the same out to the optical horizon capability as the handhelds listed above, but the SSB varieties are sometimes able to be used for local communication out to 20 miles or so. This longer range generally requires a larger antenna around 15ft long , and mounted high up, like on the chimney of a house. Not good for Opsec. Their frequency is such that at certain times of the year and certain times of day ( summer early afternoons are best) Their radio waves are also reflected from the atmosphere, coming back to earth for reception around 300-400 miles from the transmitting station. Everything between the 20 mile local horizon range and the 300-400 mile landing range will hear nothing at all. This might or might not meet your needs only you can say
Brining us back on topic the little radio we are discussing here The Pixie II is an ultra simple device that, connected to a matched antenna will communicate from your doorstep out to 40 to 60 miles, and allow monitoring of transmissions from across the continent.
Boxed up they are tye size of a large pack of cigarettes. They operate on afixed frequency, so no dials or swtches to worry about. Antenna is a 62ft length of light wire that is thrown out over bushes and non metallic fences, ideally at a height of 6 to 10 ft above the ground. They power from anything from 9 to 13 volts and sip minimal amounts of power. The communication MODE is Morse code only. When I say morse code I mean dah and dit code….the code itself can be of you own device to keep things secret between your group. Heir simplicity makes for reliability, their low cost and small size make for viability as preps, their meagre energy consumption makes for efficiency in grid down situations.
The frequencies that they operate on are in the Amateur band so to transmit with them in the here and now requires a license…… but they can be legally used to listen to radio traffic by anyone at all, no license is required for that. In my opinion they should be considered final fall-back communication devices for use when all else fails….. and that’s exactly what we are doing with them in my personal group.
I’ve tried to keep this simple and avoid too much specialist terminology.
If you need specific advice drop me a PM and I assess your specific situation off the public forum
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