|The more the better cb information|
|go to www.geocities.com/jesusglow
GOOD EXAMPLES OF BAD INSTALLATIONS
When it comes to installing 2-way radio antennas, CB, cellular phone, 2-meter, 10-meter, marine radio, etc., you need to shelf nearly everything that you have ever done with an AM/FM radio antenna. You can run a receive only radio, scanner, AM/FM, short wave, etc., without any antenna at all, one made from a coat hanger, one laying in the trunk or even drug behind the vehicle without damaging the radio. But, if you do not mount a 2-way radio antenna with care you can probably kiss your radio goodbye. Transmitters require a tuned antenna, mounted in a free space area and fed by a reliable piece of cable. There is little room for a "what-ever" attitude. Here are some examples of bad installations we have seen and helped people fix. If any of these are similar to your installation, fix it before you expect it to work properly.
Antennas mounted so low on a motorhome that none of the antenna is above the roofline.
Two-foot antennas mounted on the front corner of a pick-up bed.
Any antenna nicely sandwiched between the window of a pick-up and a camper or cap in order to make sure that none of the energy can escape the antenna.
Ground plane reliant antennas mounted on vehicles without any ground plane.
Ground plane reliant antennas without grounded mounts.
Antennas mounted to ungrounded pick-up truck toolboxes.
Co-phased antennas that have no line of site between the top 2/3's of the antennas.
Single antenna installations using RG-59 type coax cable
Dual antenna installations using RG-58 type coaxial cable.
Installations whereas the presence of shorts or opens was never tested.
Installations that never had the SWR tested, let alone adjusted.
Coax cables spliced as if it were a common 12-volt feed line.
Coax cables with the insulation rubbed totally off.
Coax cables that are severely pinched in doors, windows, hoods and trunks.
Improperly installed stud mounts.
Short antennas mounted on the bumpers of SUV's so they will fit into the garage.
Glass mounted antennas that "look cool".
Glass mounted antenna on windshields with laminated deicer circuitry.
Cheap, low-grade coaxial cable used on any installation.
Antennas mounted too close to other antennas, effectively altering their operation.
No-ground-plane antennas used with regular coaxial cables.
Regular antennas used with no-ground-plane coaxial cable assemblies.
Antennas sawed off at the top so the vehicle would fit into the garage.
No-ground-plane antenna installations with the coax grounded at the mount.
No-ground-plane antenna installations where the coax has been altered.
Insufficient wire gauge used to chassis ground an insulated mount for ground-plane antenna.
Expensive radio … cheap antenna.
If there was ever a time to read BEFORE taking action … than it is BEFORE doing a CB installation. The "modern" world of "plug-n-play" and/or "point-and-click" has literally sucked the common sense out of society. Come back to the real world please. Installing a CB isn't the same as putting together a swing set. You do something wrong and you might just burn out your radio in a matter of seconds. GO FORWARD WITH KNOWLEDGE!
Mobile CB never has been, nor can we ever foresee it as being plug-n-play equipment. I don't care what you have ever been told … you cannot just put a CB system on a vehicle and expect it to be ready to go. It doesn't matter if you put the exact same radio and antenna set up on the exact same type of vehicle ... if you don't put an SWR meter on your set up … you are flirting with an expensive lesson. Remember this ….
THERE IS NO SUCH THING AS A UNIVERSALLY PRE-TUNED CB ANTENNA . PERIOD!
If you read on a package that the antenna was pre-tuned … that only means that it was checked on a manufacturers test bench to verify that it was within the frequency tolerances set by the manufacturer. Ground plane dependent antennas MUST have counterpoise (ground plane) and unless you are driving a car that is shaped like, and has the exact same metal mass as the manufactures test bench … YOUR ANTENNA NEEDS TO BE SWR CHECKED AFTER INSTALLATION. And finally, if the packaging of one antenna hanging on the wall says that it has a tunable tip, that DOES NOT mean that the one next to it that doesn't have a tunable tip doesn't need to be tuned. The one with a tunable tip is just easier to tune.
This is a sensitive matter and you MUST get it right. How sensitive is this SWR thingy? So much so that if you move your antenna from one location to another location on the same vehicle … there is a very high likelihood that the SWR is going to change. Do not second-guess this process.
The reason you adjust the antenna is because you don't have a way to adjust the rest of the things that the SWR meter is seeing. I suppose you could take a sledge hammer and beat the vehicle up so much that the SWR would change but that is not something I would recommend or even try. The antenna is adjusted to compensate for all of the flaws that feed it and surround it. You wouldn't believe all of the silly things we have seen over the years. We get to hear all of that stuff because the antenna always gets the blame for bad SWR.
And something else … SWR meters are every bit as dumb as rocks. Too many people give them way too much credit. That is, some people actually think that an SWR meter can ignore everything except the antenna. Wrong! When your SWR meter is being used it is "seeing" everything in the area. This includes connectors, coaxial cables, antenna mounts, antenna stud mounts, the vehicle itself, and of course the antenna. And if your mother-in-law is standing close to the antenna, or your door is open … the SWR meter WILL see that and take it into consideration. There are two great forces in the universe … one is gravity and the other is magnetism. CB antennas can radiate a magnetic field that can be absorbed and deciphered by another transmitter that is thousands of miles away. So if your goat is sleeping on the roof of your car … or if your neighbors are throwing a block party in the bed of your pick-up … you're gonna have to throw 'em out until you get your SWR adjusted.
Common sense rules! If we had the choice of packaging a cubic foot of common sense or a cubic yard of intelligence with our products … we would chose the common sense. Don't let the size fool you … it has more mass!
Where to spend your cb dollars
Over the course of thirty plus years in the communications business we have repeated a statement so many times that we feel that it needs to be put into print. Its not that is hasn't blessed the pages of every communications publication that ever existed; it just seems to be something that needs to be readily available at any time. Here it is…
When you are putting together a system for your vehicle, whether on a budget or not, plan on buying the best antenna system (coax, mount, antenna stud and antenna) that you can find and go buy a radio.
Aside from a bunch of fancy options that do little to improve the performance of your system, all radios are pretty much the same. The manufacturing of CB radios is a government-regulated process. The final output power, by law, is regulated to a maximum of 4 watts. Some manufactures try to fool you by using words such as "5 Full Watts of Power". That does not refer to transmit power … they are talking about audio output power. Granted, 5 watts of audio is better than 4, but that only pertains to what you hear, not to what you send. We're sure you've heard the saying. "A chain is only as strong as its weakest link". Don't ever forget that whether buying chains or assembling a radio system. The truth is, for basic communications, it is our opinion that anything beyond a squelch, RF gain and maybe a mic gain control is an extra feature you can definitely do without.
Of course, there is absolutely nothing wrong with having all of the features, but not if the extra cost means that you are going to skimp on the antenna system. It is a bad trade off and one that is all to often exercised. The best radio with a lousy antenna system will NEVER outperform a cheap radio with a good antenna system. If anyone tries to tell you otherwise … run for the door. Cheap antenna systems are cheap for a reason and that almost always means lousy components throughout.
In many cases, it isn't always just the antenna that is bad. In way too many instances you get a piece of coax that would be best utilized if it were used to tie your dog to a tree. There is a lot of junk cable on the market! If you were watering your yard with a hose that was literally full of holes you would better understand the problem of poor coax cable. Unfortunately, you can't see RF energy pouring out, or interference pouring into a piece of bad coax, but that is what you can often end up with.
Another part to watch for is the stud mount. The stud mount needs to be mechanically strong and electrically superior. Those in the know about electronics, RF or otherwise, will tell you that the majority of problems in an electrical or electrical-mechanical device will involve poor connections that cause opens, shorts or high resistance. The stud mount is an electrical-mechanical device that must support the antenna and act as a bridge between the antenna and the coaxial feed to the radio. Again, if you are looking for cheap ones, you can find them. They are made of aluminum, or they use non-stainless steel washers that are sure to corrode, or they have cheap plastic insulators that crack or collapse under normal conditions. And some of them have all of the above!
When you shop … shop smart and you will only need to do it once. Give the majority of your time and money to the antenna system and you will be making the right moves.
Getting a Radio
THE RADIO PURCHASE
Over the years we have gravitated to simplicity. It stands to reason that the more features the radio has … the more problems you can have. Since the FCC regulates power output of production CB radios, what separates a $200 radio from a $70 radio is not much more than "bells and whistles". It is not uncommon for a person with an inexpensive radio and a thoughtfully installed and tuned antenna system to enjoy performance that far exceeds the fellow with the $200+ radio and a mediocre antenna or questionable antenna installation. Insofar as performance is concerned, it is the antenna that makes the difference … not the radio.
Every radio has a few common features … a dial or switch for changing channels, an on/off/volume control and a squelch control. If the radio has PA capabilities, a switch to go from the radio function to the PA function will be present. There is one additional feature that we like in a CB, and that is "RF gain." RF gain is a receive only adjustment that allows you to control incoming signal strength when strong signals are present and over-powering. Once we find a radio with those features, we are done shopping. Radios with the basic features are generally compact and it is easy to find a nook or cranny to place them. If your true intent is functionality, bigger does not mean better (and chrome does not make a radio perform better).
As you move up in price range, you will find features such as ANL (automatic noise limiter). When this feature is turned on, the receiver (not the transmitter) is attenuated to cut out lower level noises on the airwaves. Keep in mind that the radio doesn’t know the difference between a hissing sound or your friend saying "Come back … I need help" from a marginal distance. The ANL is okay for short distance communications, but then again, we prefer to just use the squelch and allow the radio’s receiver to have the capacity to gather up all that it can.
As far as built-in SWR/power meters are concerned, we prefer that the antenna system be tuned and tested with an external meter. Our confidence in the accuracy of the built-in meters is, at best, weak. The most valuable part of having an internal SWR meter is to offer the user the ability to spot-check the antenna system. That is, after it is set up and functioning, random checks will point out possible flaws that might occur because a coax cable got pinched, a connector came loose or the antenna hit something that may have caused damage. For more about SWR, read the SIDEBAR ON SWR at the end of this article.
One of our least favorite add-ons that started showing up in CB during the 90’s is weather band reception. Weather information is typically broadcast from major metropolitan areas and at a fairly low power. You don’t have to travel far to be out of range. Your chance of getting current information is much better from a vehicle installed AM/FM radio. We would much rather see those interested in these frequencies put the money towards a mobile scanner that will pick up the weather bands and much, much more. And if you want to maximize the features, a dedicated antenna is a better option.
SIDEBAR ON SWR
The SWR meter’s primary function is to gauge the radio’s output potential and compare that to the antenna system’s ability to absorb the radios maximum output potential. It is a simple process. First the antenna system is isolated from the transmitter and the user activates the radio transmitter by "keying up" the microphone. A calibration control allows the user to "swing the needle" to the meters calibration line. Once calibrated, a switch is repositioned and the meter opens a gate for the energy to enter the antenna system. The resulting "number" indicates how much of the radios potential is being absorbed and radiated by the antenna system. The more … the better. Please take note that when we say "antenna system" we are not just talking about the antenna itself. The SWR meter "sees" everything beyond the antenna connection as one unit. Bad coax and/or connections, improperly installed mount components, poorly located antennas, insufficient counterpoise and untuned antennas can and will create conditions that will prevent the antenna system from absorbing and radiating the radios energy. The SWR meter "sees" the whole picture.
If you do not gain anything else from this article, at least note that ALL antennas MUST be tuned to the transmitter after installation. The chance that a non-tested system is going to work properly is very slim. There are several articles in our library that offer more detail on SWR and we encourage you to read them.
|Master CB Links|
|Back to main page|