by Tunnel Rabbit, Survival Blog:
(Continued from Part 1. This concludes the article.)
ANTENNA SELECTION ADVNTAGES
For COMSEC, it is always the best policy to use the lowest power setting that still allows reliable communication. Using the best antenna for a particular situation is often overlooked as it is much more convenient to increase the power until we can be heard. If our equipment is low power then we can use a high-gain directional, or omnidirectional antenna to compensate. And using a better antenna to listen to weak signals increases our effectiveness.
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In a communication circuit using common 1/4-watt FRS transceivers, I can reliably communicate up to 4 miles in my terrain using these very low power transceivers by using one high gain directional antenna, and a scanner, or a modified FRS transceiver as receiver. Normally, the range might be only 500 yards. The range can be greatly increased if both stations used receivers connected to high-gain directional antennas. As a receive-only antenna, it does not need to be tuned using an SWR meter, but only cut to the approximate length. Common 59-Ohm coaxial cable from a satellite television system can be used. This antenna can be constructed with minimal amount of effort, materials, and skill. Yet it will greatly improve our communications. We could lose most of our equipment, yet find the material just about anywhere, and get back on air. Perhaps I’ll discuss how, in the future. Using common off-the-shelf equipment, and our knowledge and skills makes us more effective as “Indians”, and more resilient.
Knowledge of antenna construction can also be used to improve COMSEC by reducing the output of a transmitter. As an example, we could get the same advantage of low power when using a transceiver that has a low setting of 1/4 watt instead of one watt by reducing the efficiency of any antenna. We could reduce the Effective Radiated Power (ERP) to 250mw (1/4 watt), or less, out of a directional or omnidirectional antenna, yet the antenna would still be an efficient receiver of weak signals. We could also choose to use a separate receiver and antenna.
A more in-depth look at techniques of constructing and using antennas should be a part of the discussion. The best countermeasure for a SIGINT effort is not to being heard at all. Very low-power UHF transmissions scatter the least, and an FM signal drops off at a certain point, and can be somewhat limited to within a relatively, and known shorter range by the use of these techniques as discussed. An intercept station would have great difficulty detecting these signals. We can also use VHF, and methods of scattering to our advantage. The best use of antennas would greatly improve COMSEC, and be a key advantage for the guerrilla operator, or average prepper. Unfortunately, these skills are underdeveloped, because they are currently underappreciated.
SOLAR CHARGING DIRECT
I would like to report that my field testing during the last month of a device detailed in my April 2023 article Commo for Family, Group, or Community of a home made solar charger for Baofeng and Midland handhelds. It has exceeded expectations. It deserves its own article, yet I may not have time for it.
This is an important DIY innovation for preppers as it eliminates the need and expense of deep cycle batteries, a charge controller, cables and wiring, and provides the most efficient use of available PV panel power. It is more efficient than solar systems that use MPPT charger controllers and lithium batteries. And it can be a part of a very lightweight, and packable recharging station, or as a part of another contingency plan, as well as a means to enable neighbors to charge their own radios.
To my knowledge, there is no voltage drop-down device on the market that is suitable for Baofeng UV5R or Midland transceivers that require 9 to 10 vdc for their charging bases. Fortunately, you can easily manage to cobble together our own charging device by use of my instructions for as low as $10 each, or less. I made 25 of these, and a few for good neighbors who will likely not be fully prepared. For those who belatedly realize that they were too slow in their efforts to prepare, I’ll trade for ammo, since it can be used as a substitute for a small $500+ PV system with storage batteries.
With this device, as tested in northwest Montana during the rainy/cloudy months of spring when insolation (sunshine) reduces PV panel output to 10% to 20% of it’s maximum rate output. Using a single 100 watt panel, 4 Baofeng UV5R transceivers with 1800aH batteries can be kept operational 24/7, and 4 others charging, or fully charged. The number of radios that could be charged might have been higher, yet for the purposes of the test, the limit was determined by the actual amperage output of the panel as installed in a less than ideal setting, where the maximum amperage of the nominal 12 volt panel did not exceed 4.0 Ah. VOC (Voltage Open Current) was 21.5vdc. I surmise that during long summer days, perhaps up 16 transceivers could be charging, with 8 operational on standby (receive) 24/7 with only one 100 watt PV panel. I have not tested the limits, but kept to conservative, or realistic expectations, and the results exceeded expectations. Results will vary at different locations and weather conditions. A Baofeng UV5R 1800mAh battery, when completely discharged, draws no more than 0.180mA when charging, and quickly tapers down. The UV5R is a power-efficient receiver as are some scanners, drawing only .075 watts, when turned on.
In another test, a 10-watt panel easily kept one transceiver operational 24/7, and another charging, or fully charged during this spring during variable weather conditions. A 10 watt PV powering this voltage conversion device will also operate Argent Data Systems repeater 24/7 attached to a Baofeng UV5R without a dedicated storage battery. In fair to good weather, a minimum of one 20 watt panel would be needed to operate a cross band repeater comprised of two Baofeng UV5Rs using 3800aH batteries, versus the standard 1800aH batteries.
Extrapolating from these results and data obtained, it would like be possible to keep at least 2 transceivers, and therefore two stations operational, a base station and a lookout post, during the darkest winter months in northwest Montana when there is, on average, only 1 hour of insolation per day. For this scenario, I would use 200 watts of PV power and 8 chargers charging 8 Baofeng UV5R transceivers. Or better yet, install a 100 watt panel near the lookout post so that it can provide a small sustained amount of power for a charging station. Midland FRS/GMRS transceivers have the same voltage specifications, yet lower power requirements, and could be charged with this set up with similar results. None of my Baofeng or Midland radios using their factory charging bases were damaged during this month-long field test. Given this field testing, I can now assure experimenters that they will be pleased.
In an austere setting where there may not be available a standard PV system, and when storage battery capacity is taxed, or limited, and declines within a few years, and where a lightweight portable system is required, this is a must-have device.
CONCLUSION
In this day and age of cell phones and satellite phones, we are habituated to that paradigm, and too often are looking for a ‘buy one and be done’ solution. We are accustomed to buying one, whatever the item, and considering ourselves safer for the purchase alone, be it the latest in knives or guns, or some promising gadget to make ourselves feel more secure. Unfortunately, we are not placing enough emphasis on knowledge and skills needed to live with sustainable technology that happens to be low tech that is also the most appropriate tech for a dystopian future. Fortunately, we can buy radios that are relatively simple to operate, or very complex and versatile. In the end, keeping it a simple as possible to accommodate the lowest common denominator, or the least capable person in a group, is the best policy. Leave the complicated stuff to your radio ‘nut’, or resident expert.
