Cb Question (rookie)

If your radio has a built in SWR meter, I would just use that one to tune the antenna! Done deal

That's what I do, I've just heard the external meter is more accurate

Shouldn't make a bit of difference. Use Bullwinkle's numbers and you will be just fine. CB radios only have a 2-4 mile range anyways. An extra 100 feet won't matter!

Shouldn't make a bit of difference. Use Bullwinkle's numbers and you will be just fine. CB radios only have a 2-4 mile range anyways. An extra 100 feet won't matter!

Yes a properly tuned antena does make a difference. I have a Conex3300 high power and I get out 10 easily. 12 to 15 on flat land. All 3 of my radios,1 in truck and 2 at home, are all above a standard truckstop radio and I don't intend to burn out the finals due to an unturned antenna

Troubleshooting the inline SWR Meter Problem

If you're going to use an inline SWR Meter for testing set your radio controls as they would normally be set for regular operation. Don't set the radio in CAL Mode.

Is the inline SWR Meter designed for CB radio operation? 27Mhz or (11 Meter Amateur Radio Band ) is the frequency range of a CB. Somewhere in the SWR Meter instructions it should tell you what frequency it is for or it may just say hey this SWR Meter is designed for CBs

If you purchased a more sophisticated SWR Meter they have interchangeable "slugs" that will set it up to operate on different frequencies so you can use it on radios that operate out of a CB's frequency range. Check to make sure the SWR meter is setup to operate on Citizens Band.

If the SWR Meter was designed for amateur radio operation it could be setup to operate out of the CB radio frequency range and can cause you big headaches.

Also check the coax "jumper Cable " you're using between the radio and the meter to make sure it's the right impedance match for operation in the CB frequency range. You want to use coax rated at 50 ohm impedance. It should have writing on it that says something like "RG58/AU" and may even have the impedance written on it "50 ohm" Is this cable in good condition? Connectors attached firmly, hopefully soldered on not the twist on kind. If its a factory manufactured 50 ohm cable you should be in good shape

Was the SWR meter purchased new in a factory sealed box? It could be defective. Something is a miss when you have it plumbed into the feed line that's for sure.

Testing with the Radios Built in SWR Meter

Remove the inline SWR Meter and attach your antenna feed line directly to the radio.

When you use the built in SWR Meter inside the radio do you go thru a calibration process before you check your SWR?

With the built in SWR Meter in your radio properly calibrated what are you getting for an SWR reading?

If the SWR is 1.6 / 1 or lower 95% of your signal is getting to the antenna. Call it a day unless you're up for a project and want a learning experience in tuning an antenna. (Not a bad thing if you need something to do, hahaha)

A bit of Radio Theory

Keep in mind the SWR Meter does not tune your antenna. It only checks what is called Standing Wave Ratio. An SWR Reading of 1.6 /1 is saying that 95% of your RF ( Radio Frequency ) power is getting out onto the antenna and 5% of the power is being reflected back towards the radio. Think of SWR as the back pressure in an exhaust system.

An antenna is tuned by either making it physically longer or shorter. Antenna turners can also be used to accommodate an antenna that is not cut to the right length. They are impractical when operating in a very narrow range of frequencies. CBs operate between 26.965 MHz and 27.405 MHz which is a very narrow band. Ham Radio operators use a tuner so they can make 1 antenna work over a wide range of frequencies.

Guy's radio in stock configuration runs at 50 watts output and is not a standard radio you could buy off the shelf. Most stock radios run at 4 watts output. I'm sure he is also running with a good quality antenna system. He's getting extended range but is also paying the price with more expensive gear which is not a bad thing in the least. What type of antenna are you running with on the truck? You are getting excellent range!

Also keep in mind that unless atmospheric conditions are right to "skip" signals off the ionosphere that surrounds the earth radio communication is limited to line of sight. This is the brick wall that really determines your transmit range. In theory (not necessarily in practice) an antenna mounted on a 100 foot tower has a capability of transmitting about 15 miles. Because of the curvature of the earth you can see this far before the horizon drops off. Another term for this is called your "Radio Horizon" Add another 1000 watts of power and guess what you may be able to transmit a few more miles but not much farther. A radio operator from the military once took me "If conditions are right, give me 5 watts of output power and I'll talk around the world"

If you can transmit 5 miles from an average mobile CB radio you are doing great. If you need more range get the antenna higher off the ground which is impractical in mobile operation.

Antenna Theory in the frequency range that CBs operate in (27mhz) is not cutting edge science and has been around a long time. One of the best configurations for Large Semi Trucks with a trailer is the dual mount antenna system on the left and right mirrors. This is by no means the best or only configuration however this setup is ideal for communicating with other people in front of or in back of you. It also works pretty good to work other stations that may be on your sides because the truck is often blocking your signal and the other antenna may have a clearer path.

If you drive flat bed, tanker or some other configuration that will not block the signal of an antenna on top of the tractor a roof mounted antenna is a good setup. This type of antenna works equally well in all directions.

Well Boys and Girls that's radio theory class 101 for the day. Keep the questions and comments coming in!

BJ Moose