Question about Cobra 29 WX NW ST 40-Channels Base CB Radio

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Matching c b antenna with c b radio

I have been trying to match my new cb radio with an antenna that is only 24 to 25 inches tall it is a magnet mount mounted in the middle of the roof of my 1998 toyota king cab pick up. The radio is with a built in SWR meter. The problem is I have tried many times to match it according to the manufactures instructions but I have had no luck. I have tried to transmit after matching it . With no come back I hope I haven't damaged the radio. Oh yes the antenna has a center load. RG58 U is the type of cable I'm using.


Ed Courtright

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  • riverrat047 Aug 06, 2008

    To all C B'rs

    Especially those just starting out or over like me. I had a problem when I started out with a c b radio that not only had the regular 40 channels but also had 7 weather channels as well. I was trying to run 2 bands on a one band antenna. To use both you have to use a two band antenna. And if your radio has a built in SWR meter do not use it you have to have an external SWR meter between the receiver and the antenna. That was my other problem I was using the built in SWR meter when I should have used an external one. I hope this is of some help.



  • Dean Pitts
    Dean Pitts May 11, 2010

    When you are trying to set your SWR's, are you using an inline SWR meter, or are you assuming you are setting the SWR with the radio's meter and the SWR knob on the radio?

    You can only set the SWR with an external meter and moving the stinger up and down on the antenna. The only thing that the SWR CAL on the radio is for is setting the meter to what the actual antenna SWRs are, which is used the same as a dummy light on a car.




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Here is some information that will help you test SWR with an inline watt meter. To get proper results you need to use an inline watt meter. Here is a really good site you can go to for help

Equipment needed: SWR meter, short jumper coax 3 foot.
matching c b antenna with c b radio - midland.jpgProcedure: The SWR meter needs to be placed in line between the antenna and the CB. Connect the antenna (normally connected to the back of the CB ) to the connector marked "Antenna" or "Ant" on your SWR Meter. Connect one end of the short jumper coax to the "transmit" or "Xmit" on the SWR meter. Connect the other end of your jumper coax to the CB.
Assuming you have a standard SWR meter the switches should read as follows: REF or SWR, FWD, and there should be a slide switch marked "set" or "Adjust". If different consult your meter's owners manual.
With the radio on the lowest channel (1 on CB) and the SWR meters switch in the Forward (FWD) position, depress the transmit switch (key up) located on the microphone. While holding the unit in this transmit mode, adjust the meter needle to the set position using the Set or Adjust knob on the meter. As soon as the needle is in alignment with the corresponding mark on the meter face, flip the switch to the Reference (REF) position. The meter is now showing your SWR on channel one. Note the value and quickly release the microphone switch. Record this reading.
Repeat the previous step on channels 19 and 40.
How to read your results: If SWR on channels 1, 19 & 40 is below 2.0, your radio can be operated safely.
If SWR on all channels is above 2.0 but not in the "red zone" (normally over 3.0), you may be experiencing coaxial cable reaction (bad quality, wrong length, etc.), insufficient ground plane, or have an ungrounded antenna mount.
If SWR is in the "red zone" on all channels, you probably have an electrical short in your coax connectors, or your mounting stud was installed incorrectly and is shorted. Do not operate your radio until the problem is found, serious damage can occur to your radio.
If SWR on the lowest channel is higher than it is on the highest channel, your antenna system appears to be electrically short. Your antenna length may need to be increased.
If the SWR on channel 40 is greater than that on channel 1, your antenna is considered to be "LONG" and reduction of physical height and/or conductor length will correct this situation.

Posted on Aug 15, 2008


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