Tip & How-To about Radio Communications

ALL ABOUT RADIOS

Radios especially AM bands are simple to work with. Its mostly about antenna adjustments, microphones,Swr, grounding. Check SWR on radio to say 1.5 ratio, which is good. Ground the heck out of it. Drive 8 foot copper stakes into earth,also to water pipes,metal filing cabinets,chain link fences...Connect all these to your radio metal, or black ground. The better the ground stronger the signal. Make sure Antenna is off the ground 15 to 35 feet. I use Tv pole on mine.Use big supergrade coax low-loss 50 ohm. All Am radio is 50 ohm loaded. Internal adjustments to radio is not needed.. But, if you do, make sure you chart what you did and mark your IF canisters with nail polish(setting factory). Clip diodes for Modulation or turn up a VR4 or VR1 or so. Each model has different setting Variable Resistors(VRx). Make sure you read all about it on DEFCOM RADIO MODS or SNAKE DOCTORS RADIO MODS--Before attempting internal adjustments..Use micro screwdrivers only. Remember the best antenna for CB frequencies is "102 inches" 8.5 feet. Build your own and have fun.

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I have a galaxy dx48t it has no calibrate on the SWR meter, how do I check my SWR?


Best way to check your SWR is with a separate SWR meter installed between the radio and the antenna. Be sure to check the input and output sides of the meter. With the meter in-place, key up your radio and adjust your antenna for max output / minimum loss. This may require that you change the length of your antenna and repair any questionable connections. Also, be mindful of the fact that CB radios broadcast in AM. That means your antenna should be well grounded to your vehicle. AM radios rely on "ground plane" antennas, which means that your entire vehicle (with good grounding) becomes apart of the antenna system. Hope this helps.

Jul 09, 2014 | Radio Communications

2 Answers

Got it peaked and tuned and hooked up a new coax and mirror bracket and my swr is at 4. Before I did all this I had the stock coax and swr was under 2. What do I need to do to get the swr down?


The antenna needs to be tuned. The reason all of a sudden your SWR is a 4 when it used to be a 2 is, after a peak and tune, the radio is putting out more power, there for more RF energy is being reflected back into the radio. That is why the antenna has to be tuned.

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 CAL. (CAL stand for calibrate.
3. Key the radio. (Important. Do not talk while keying the radio.)
4. turn the CAL knob up until the meter hits the CAL mark.
5. Now while still keying the radio flip the meter switch to SWR.

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 17, 2010 | 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

I hooked up my radio and when i push the mic the red antenna light came on so i grounded the radio better still did it changed the braket for the antenna still same thing changed antenna still samr thing running out of things to do what is the problem?


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 CAL. (CAL stand for calibrate.
3. Key the radio. (Important. Do not talk while keying the radio.)
4. turn the CAL knob up until the meter hits the CAL mark.
5. Now while still keying the radio flip the meter switch to SWR.

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 10, 2010 | Uniden GRANTLT 40-Channels Base CB Radio

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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