Radios in pic: Left Midland 75-822(CB),Left Center Icom ID-51a(UHF/VHF),Top Right Yaesu FT-817(HF/VHF/UHF),Bottom Right SuperStar SS-121(CB). *See special notes at bottom of article*
Ham radio, Part 2
In the previous post, we discussed how we invested a little time and effort, and in return, we received a piece of paper from the FCC that gave us privileges to use UHF, VHF, and even some small slivers of HF spectrum.
What does all that mean? Well first, lets focus on the most frequently used segments of the electromagnetic spectrum: UHF, VHF, and HF. UHF occupies 1m (300Mhz) to 1dm (3,000Mhz), VHF ranges from 1m (300Mhz) up to 10m (30Mhz), and HF ranges from 10m (30Mhz) to 80m (3.5Mhz), and into 160m (1.8Mhz). Bands and frequencies will be covered in more detail in a future article.
UHF stands for Ultra High Frequency, which covers from 3Ghz to 300Mhz. TV’s ,cell phones, GPS, bluetooth, satellite radio, and WiFi, among other things, occupy this band. For the most part, consider UHF a “local” radio option. Typically, it performs better in urban environments, compared to VHF and HF. Buildings not only reflect radio signals, but they also absorb them. Ever notice that your phone may not operate as well in the center of a large building? Well, that is because your phone is a fancy UHF radio.
VHF is a lower frequency band that begins where UHF stops, at 300Mhz, and covers down to 30Mhz (almost into CB territory). It’s primarily used for FM radio, aircraft, marine communications, and land-based, mobile 2-way radio systems (law enforcement, business, military, emergency, and private use). VHF has less path loss (the reduction of power density of a wave or signal as it propagates) than UHF, and more antenna capture area, so it is a local to mid-range radio option.
UHF and VHF mostly rely on line of sight for range. We’ve all seen the little Motorola, Uniden, or other brand handheld FRS (Family Radio Service)/GMRS (General Mobile Radio Service) radios on the shelf at Wal-Mart or a sports stores with big writing on the package that reads something like, “30 mile range." Is their range really 30 miles? Probably not in what you or I would consider real-world scenarios. By law, the FCC limits the power on those radios to 0.5 watt, since they are for non-licensed individuals and can only transmit on certain pre-determined frequencies known as channels between 462, and 467Mhz.
Finding the required “Line of Sight” one would need for the distance these products claim, would require both parties to be on elevated positions with nothing in between. Basically, from one mountain top to another with no obstructions in between. Unfortunately, our everyday communications do not happen from mountaintop to mountaintop. Even the flattest place on earth has curvature, and line of sight around 7’ish miles, for two 6ft-tall radio operators.
Half a watt? Thats not much at all! There are groups of individuals in the ham community (Team RCO included) that enjoy the challenges of making contact on low power over long distances, a method called "QRP." However, operating on 0.5 watt because thats all you can legally transmit, can be frustrating.
These factors, compounded with the low-power and low-gain antennas, mean less than a mile and, usually, less than a few hundred yards communication distance.
When you become a Ham and receive your FCC callsign, instead of the 0.5 watt of the FRS, you are allowed to legally transmit at 1500 watts on much of the VHF spectrum. Most mobile VHF radios are less than 75 watts, and UHF units are slightly lower than that. Why not 1500 watt? I mean, it’s legal right? Most vehicle manufacturers recommend against going over a certain amount of RF power, to ensure interference doesn’t cause issues with the vehicle operating systems, or the vehicle's power. If you like 99.98% of vehicles on the road have a 12V system, it means you’ll need to be able to supply over 125 amps, with the 12V to cover the 1500 watts. To put that amperage into perspective, the recommended breakers in your garage or home fuse box on a circuit for a MIG welder are rated at less amperage than that.
Something to keep in mind when discussing frequency and its use is that, all else being equal, the higher the frequency, the shorter the distance you can communicate, effectively, line of sight. To communicate with UHF and VHF over long distances, you can use a repeater, which acts much like a cell phone tower. Stay tuned for ways to use repeaters for communications, with will be covered in a different article.
HF is reserved for the General and Extra class radio operators, and we will dive into this spectrum segment at a later time. However, Citizens Band or CB, as it is most commonly referred to, lies at the top of the HF spectrum and does not require a license for use. CB is a popular radio communication method that works great, provided you don’t have high expectations, and don’t mind hearing truckers running a linear amplifier that blows out 1 kilowatt (995 watts over max legal limit) of over modulated distorted audio, bleeding up and down the neighboring channels, making them unusable. The 11 meter band, which ranges from 26.965Mhz- 29.405Mhz, does not work well for off roading communications. The frequency is low enough that, at times, by accident, or intentionally (condition modeling if you’re so inclined), you can make longer distance contacts, but atmospherics and solar cycles come into play, and should not be relied on. One of the aggravating limitations with a channelized system like CB, FRS, and GMRS is that there are only so many channels that you can use. CB has 40 channels. FRS and GMRS share 14 channels, and, in addition, GMRS has 9 more channels.
Another downside of CB is it’s frequency. It is low enough that it does not penetrate well, and suffers losses to diffraction, and absorption. The wavelength is long enough, and so a decent antenna needs to be almost 9ft long. As you can deduct, the 3, 4 , and 5-foot antennas readily available are a bad compromise, at best. All these factors combined make this communication method unreliable and undesirable. I own more than one CB, not because they work great, but because it’s the lowest common denominator and very popular when on the trail. The audio clarity and definition difference in using a $30 handheld UHF/VHF radio and a CB is like comparing a movie in 1080p or 4k to a late 70s low budget film.
Is there something we really like about CB? It’s free to use, and sometimes you get what you pay for.
Check back for the next post covering bands and frequencies.
*The handheld Midland CB radio is used when we at Rock Creek Overland, need to communicate to non-hams at off road events. It's effective range is not very far. If the trail group is large, communication from front to back of the pack may be inconsistent. Out of the vehicles it is better, it's best best role is as a spotter's radio. The Midland can be hooked up to a external antenna that will greatly extend it's range(equal to a traditional mobile rig setup). The Icom handheld range in much better(both when using it as a handheld and when connected to an external antenna)and we can even use it on digital protocols through repeaters that are available to Tech Class Ham Radio Operators to talk to other countries, or back to our home towns from our destination. The Yaesu rig has been used on HF bands to talk as far as Russia using a homemade antenna, but has also been able to communicate all over the USA. The CB radio will reliably communicate a couple miles or less when in a typical off road oriented mobile setup(on the east coast trails more like .5 or less). The interesting thing about all these radios, is that they all transmit the same power output.
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