Who Uses CB Radios?

[Industrial Toys]

Too bad you can't elaborate. You could have sent the spooks around in the black sedan.

 

[Looking4new]

My information on CB antennas is that the ideal antenna would need to be 27' long for the 27 mhz frequencies.
A coil, whether it is submerged in oil or not takes up the 21' of antenna that you cannot run on a mobile platform.
The oil coil is supposed to aid in cooling. So they say. The antenna, if one so chooses can run up to 1,000 watts through it and the coil would cool the antenna so you don't melt it. This is what they ( the people that make these) say. It may be a marketing ploy or not. I run them because one was recommended to me many years ago and that is mostly what I run. I get 'out' good and receive just as good, running a stock Uniden radio.

 

[Industrial Toys]

I wanted to buy a Uniden with scan function to find the yocals who drive around with CB antennas. But it became so complicated as to which version had the good finals, that I gave up for the time being. My new $3.98 rig does have up down channel buttons and I find that if I hold it down, I can hear if there is some activity on some channel, so I may just add a switch. Kind of a poor mans scan function.

 

[Jstpssng]

I stopped using coils because it's always where I snapped them while trying to sneak under a tree. Then again I run roads where the only sane people travel are Jeep people.
Oh wait a minute, that last might be an oxymoron.

 

[Looking4new]

I stopped using coils because it's always where I snapped them while trying to sneak under a tree. Then again I run roads where the only sane people travel are Jeep people.
Oh wait a minute, that last might be an oxymoron.

Trust me, some of the roads I take my tank train on (85' long) aren't much wider and we quite often are in 'older' gravel pits the M.T.O. owns with a goat trail in and lots of over hanging trees.

 

[k0ua]

My information on CB antennas is that the ideal antenna would need to be 27' long for the 27 mhz frequencies.
A coil, whether it is submerged in oil or not takes up the 21' of antenna that you cannot run on a mobile platform.
The oil coil is supposed to aid in cooling. So they say. The antenna, if one so chooses can run up to 1,000 watts through it and the coil would cool the antenna so you don't melt it. This is what they ( the people that make these) say. It may be a marketing ploy or not. I run them because one was recommended to me many years ago and that is mostly what I run. I get 'out' good and receive just as good, running a stock Uniden radio.

Hm... a 1/2 wave dipole on 27 mhz would be about 17.33 feet. There is a nice formula for building and cutting antennas. For a dipole the formula is 468/freq in Mhz. will yield the dipole overall length in feet. For a 1/4 wave vertical it is 234/freq in Mhz. These are rules of thumb, some trimming will be needed to achieve a good match to 50 ohm coaxial cable.

As for the loading coil making up the "rest of the length", that is a popular misconception. It is not even remotely correct. Shortened antennes exhibit capacitive Reactance at their feedpoint, the loading coil which is an inductor, adds inductance to cancel out the capacitive reactance to get a good match looking into the Resistive part of the equation. MANY MANY other factors come into play, here also such as ground losses, depending on where the antenna is mounted and the Q of the coil. Oftimes the better the match to the coax of the antenna, the worse the antenna efficiency is. Of course even a poor CB antenna with lossy low Q coil, will probably have far better efficiency as a percentage than the best ham antenna operating at a lower frequency say like 3.8Mhz or even 7.2Mhz.

Without question the very very best mobile vertical antenna you could possibly achieve on your vehicle at 27 MHZ is a 1/4 wave vertical. ANY loaded antenna will exhibit less efficiency. This is not to say they cannot work, and work well even. But they are compromised. ALL of them.

There is Much to know about antennas. I have been studying the subject for over 50 years. And I have a long way to go. There is more hype and downright lies told by manufactures of 27Mhz antennas than almost any subjects on the planet.

If you are to start down the long dusty road of learning about antenna theory and trying to understand the how and why things work or don't work, you will quickly discover you must discard all of those things you think you know now. For almost everything you have learned in popular culture or picked up from other users is wrong.

 

[k0ua]

If anyone would like to learn about antennas, a good place to start would be the ARRL antenna book.

978872599871 |

 

[charlton289]

I run a one of those new cobra with the color changing face I have who owns a CB shop and he tuned it up for me and I run a Wilson mini will magnet mount in the center of my roof on my S10 it works pretty good. When I was driving truck locally I had in there but being retired I just use it to talk to friends and it has weather band that is what I use for just used to having it it doesn't cost to have it so why not.

 

[Looking4new]

k0ua; Thanks for the info.

 

[skipperbrown]

K0UA (which looks a whole lot like a FCC station ID) is right. Antenna theory is extremely complex and antenna manufacturers use the complexity along with their version of snake oil and marketing to confuse the consumer and sell their products. They use terms like dBi to make you think you are getting something you are not. Throw in some misnomers like 'antenna tuners' which do nothing to tune your antenna, rather they make your non resonant antenna acceptable to your radio (and turn your signal into heat) and you have a recipe for a radio that doesn't radiate much power. The manufacturers sometimes hide the fact that a vertical antenna has 2 parts, the vertical element they sell and the other side of the vertical element which is just as important, the ground plane, which is generally your vehicle. As noted above, whenever you shorten an antenna, you are compromising something, usually radiated power and bandwidth.