Tip & How-To about Radio Communications

SWR Setting

Antennas for all radios need to have the SWR set, STANDING WAVE RATIO. Which means the antenna needs to be the correct length for it to work properly. Most people stick them on and start talking.. This is not good pratice to do. The lower the frequency the longer the antenna needs to be. The higher the frequency the shorter it needs to be. ie. 80m ham antenna needs to be around 67 ft long. and a wifi antenna needs to be just less than an inch. soo, Your CB is on 26.965ch1-27.405ch40 so ch1 is lower freq than ch 40.
obtain swr meter. inline with the radio - meter - antenna..
check swr first on ch1. then check 40 if there both good try to even out both so that there around 2.0 or less ideal is 1.1 to 1 or 1.5 to 1....
Now if ch1 is higher than ch40 = need to raise the antenna make it longer.
If ch40 is higher than ch1 = need to shorten the antenna.
some antennas have an adjustable whip. ie wilson, k40, predator10k, etc.
just adjust the whip to obtain low swr ...
some other antennas don't have whips to adjust. like Francis and OEM antennas on most trucks from the factory. these either need cutting like francis. or the oem style has a cap and wire wound under it. trim little bit at a time.1/8inch or less. if you never set swr before always try to find a good HAM operator to help you. or a decent cb shop. MOST will not charge you to do them. and Good Amateur radio operators and Good CB Shops will have an Antenna Analyzer made by MFJ.. This is what we Use here AnyMHz.com at our shop.There more accurate then a analog meter alone. And it will not interfere will people on the air like a swr meter.
Anyone that needs help please feel free to contact us. We're glad to help.

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When my calibration needle is all the way in the area my swr is really high


When your needle is all the way in the RED, your swr IS really high. That's what the meter is telling you. You need to clean all of the antenna connection points and adjust the length of the antenna to reduce the SWR (standing wave ratio) which is basically resistance to transmitting signals.

Oct 15, 2013 | Cobra 29 LTD CHR CB Radio Chrome Special...

1 Answer

how to set swr galaxy dx 949


you do not "set" swr.you cannot set it on the radio. the radio can tell you what yourswr is. it can take an swr measurement. swr has to do with the antenna system. in order for the radio waves to radiate from the antenna properly, the physical length of the antenna must match the length of the radio waves. if the antenna is too long or too short you will have a higher swr ratio. the higher the ratio the less energy will leave the antenna. but that energy needs to go somewhere, so it goes back into the radio which causes damage and can ruin a radio.

first turn the channel to 20. then switch the meter switch to CAL. then key the radio. while keyed, turn the CAL knob up until the needle in the meter gets right to the CAL Mark. next flip the meter switch and key the radio. where ever he needle is, is what your swr is.if it is more the 1.5 that's getting high. if its over 2 you are in the danger zone. if its over 3 you are damaging your radio. you must repeat the calibration proceedure for every channel.to figure out weather your antenna is too long or short, you compare the swr readings from channel 1 and ch 40. if the swr is higher in 1 then on 40 the entenna is too short. if its higher on 40 then 1 its to long.

Aug 05, 2011 | Galaxy Radios DX-949 40-Channels Base CB...

1 Answer

won't send out. I have replaced mike already.


if the Mic gain is up. and an antenna is connected. its possible that the transmit circuit is blown out. this is definitely the case if you have been operating the radio and the red ant lift has been lighting when you key up. that means your antenna was not tuned to the radio and your swr was too highroad. swr is standing wave ratio. basically if the antenna is not exactly the right length thenyou create a standing wave that does not leave the antenna and bounces back down the coax into the radio which destroys the transmit circuit. if when you key and there is no signal output then it is shot.

but make sure the cb pa switch is on cb.

Jun 15, 2011 | Cobra 29 LTD CB Radio

2 Answers

I don't understand how to adjust the SWR or how the built in meter works for my DX949.


Here is a basic instruction on how to adjust the SWR. When you adjust the SWR, you are not changing anything on the radio. You are actually tuning the antenna for best SWR. The lower the better. SWR stands for "Standing Wave Ratio" Or in layman's terms, SWR is energy that is reflected back into the radio. The higher your SWR reading, the more RF energy that is not leaving the antenna, and getting reflected back into the radio. This can cause damage to the transmit section of the radio. The length of the antenna is what will change this. The length of the antenna must match the length of the radio wave. The following instruction will explain how to take an SWR reading, and how to use that reading to ascertain weather the antenna is too long or too short.

Here is a quick explanation of the meter. There are 3 settings for the meter. SWR, MOD, and PWR. When you are not keying the radio the meter will show you your receive signal. How strong some ones signal is. When you have the switch on MOD and key, when you talk it shows you modulation. How much audio you are putting through the radio. When its on power, and you key the radio, it shows you your dead key wattage.

Tuning your antenna:

It is important to tune your CB radio antenna to the proper length. The length must exactly match the wavelength of the frequency you transmit on. Or be really really close.

All Cb antenna's have a way to adjust the length of the antenna. If it's a mag mount, the metal whip can be slid in and out of a metal collar. Usually a set screw. If its a fiberglass whip, the way to tune it is on top. It either has a small metal rod with a set screw to adjust the length, or it threads in and out to adjust length.

Either type you have it will need to be adjusted for proper length. Here is how to tune the antenna to lowest SWR.

Some radios have a built in SWR meter. Some do not. If yours doesn't have an SWR meter, then you have to use an external SWR meter. Radio shack carries one, and you can find them cheap on ebay.

If you have a built in SWR meter or external, the procedure is the same:

1. Turn the radio to CH 20.(This is the center of the band.)
2. Switch the meter switch to SWR
3. Key the radio. (Important. Do not talk while keying the radio.)

Where the meter falls after that point is you SWR reading. If its above 3, that is real bad. 2 is not gonna kill your radio but its not the greatest. 1.5 and under is a good place to be, but the lower the better.

If your SWR is high, Here is how to find out if your antenna is too long or too short.

1. Turn to CH 1
2. Repeat SWR procedure. You must calibrate every time you do it.
3. Remember the SWR reading.
4. Turn to CH 40.
5. Again repeat SWR procedure.
6. Compare the reading between CH 1 and CH 40.

Now if the SWR is higher on channel 1 then channel 40 your antenna is too short. You must make it longer.

If the SWR is longer on channel 40 then on channel 1, then the antenna is too long, you need to make it shorter.

Make height adjustments about an eight inch at a time, and take reading each time.

once the SWR is significantly lower and the reading on channel 1 and 40 are about the same, you a about matched. At this point turn the radio to the center of the band, channel 20 and take an SWR reading.

You should now have a low SWR reading, 1.5 or under. If you are 1.5 or under, you are good to go.

If you cannot get the SWR to an appropriate level, there may be an antenna problem.

Nov 16, 2010 | Galaxy Radios DX-949 40-Channels Base CB...

2 Answers

tunning the antenna on radio shack cb trc-447


After installing the antenna, follow these steps to adjust the
standing wave ratio(SWR).
1. Turn on the CB.
2. Set S/RF/SWR/CAL to CAL.
3. Key the Mic and rotate SWR CAL so the meter points
to CAL.
4. Unkey Mic.
5. Set S/RF/SWR/CAL to SWR.
6. Key Mic again and note the actual measurement on
the SWR scale. Refer to the following table to interpret
the reading.

1:1 - 1.5 Great
1.5 - 2:1 OK
2:1 - 3:1 Not So Good
Higher than 3.1:1 Terrible

The ideal standing wave ratio (SWR) is 1:1, or a meter
reading of 1 on the SWR meter's top scale. A SWR ratio
of 1.5:1 to 2:1 is excellent for most mobile CB antenna
applications.

Check the SWR on Channel 1 and Channel 40
If the SWR is higher on 1, make the antenna longer
If the SWR is higher on 40, make the antenna shorter
Most antenna's are adjustable. Make small adjustments at a time.

Oct 10, 2009 | Radio Shack TRC-447 CB Radio

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