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Instructions for a swr meter/cb radio

I have an odl micronta swr meter.Has swr/cal switch,cal addjust knob and a selector switch for 1-2 antennas.I have on operating info

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An SWR meter is used to see how well your antenna is matched to your transmitter output, just like using the correct speakers with an amplifier.

There are usually two readings. FORWARD and REFLECT
or FWD and REFL

Firstly, make sure the antenna selector is in the correct position and set for the antenna you are using.

Next, switch your meter to FWD (FORWARD). Switch your transmitter to low power and press the microphone key.

Next, adjust the CAL knob for the maximum power reading, but not so far that the meter exceeds maximum!

Keep the microphone key pressed and switch to REFL (REFLECT). If your antenna is matched, the meter should now give a low reading. If the reading is very high, you must match your antenna by making adjustments or by using a matching unit.

A poor match will mean a poor signal. A very poor match can damage your transmitter and cause interference.

When you have a good FORWARD reading and a low REFLECT reading, your system will be reasonably matched and you can then use higher power. Remember that you will need to reduce the CAL knob to a lower setting when running high power.

Posted on Mar 06, 2008

  • Palmbeach
    Palmbeach Mar 06, 2008

    Oh boy....I forgot to tell you how to connect the meter.

    Connect your antenna to one of the antenna sockets on the SWR meter. Then using a short patch lead connect your transmitter to the TX (Transmitter) socket on the SWR meter. The patch lead must be made from 50 ohm coaxial cable with the correct plugs on each end.

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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

Which pots do I use to calibrate swr and rf meters on 29classic to match extral meter?


VR5 tx power meter VR6 antenna warning light
There is not pot for swr cal internally. I guess the cal knob broad range pot or variable resistor. Swr readings after user calibration knob on front of radio, for meter should be close. Obviously not as good as external with larger scale meter. If you can not calibrate meter on face with this knob your radio may have less than 4 watts deadkey.
Just to be on the same page. Understand that SWR is a reading of antenna system condition or tuning of antenna to vehicle mounting location. This is a brief description.

Jul 07, 2011 | Cobra 29 LTD CB Radio

1 Answer

I just got a cobra 29ltd army edition and i cant get the SWR right


Takes some time to get it down if you are new to it. Here is a step by step instruction on setting it.....



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 12, 2010 | Cobra 29 LTD CB Radio

1 Answer

I just need to know how to use it for conversations and what every turn dial means.


you need to hook this up to an antenna. If you are putting it in a car, you need a mobile antenna, if in a house, you need a base antenna. The antenna needs to be tuned for best SWR or you will damage the radio.

Starting from the left of the radio.

Knob 1. Volume/ squelch. The little knob does the volume of what you hear. Big knob squelches out static noise.
knob 2. Dynamike. This is the volume of your voice transmitted. Its how loud people hear you.
Knob 3. RF gain. This is the receive sensitivity. The higher you turn this, the further you can hear. There is almost no reason for you to have this anywhere but full.
knob 4. Delta Tune. This knob should be in the center. If you encounter some one transmitting off frequency, you can move your receive up and down frequency so you can tune that person in. It does not effect your transmit frequency.
Knob 5. CAL. This is to calibrate the meter for taking an SWR reading off the antenna.

Switches starting form the left.

Switch 1. Meter switch. S/RF - will show on the meter, Your signal going out when transmitting, and the signal coming in while receiving. SWR - will show on the meter, your SWR on that channel after you have calibrated the meter. CAL - This is used to calibrate the meter in conjunction with the CAL knob.

Switch 2. ANL - Automatic noise limiter. - This gets rid of electrical interference noise from the vehicle, or other interference sources. ANL/NB - This is the same as ANL, but with NB "noise blanker" This function blanks louder noises that may make it hard to hear people. It's kind of like an automatic squelch, but not nearly as effective as the actual squelch. Also, NB will lessen your receive in that, really low signals will be blanked out.

Switch 3. CB - the radio is in CB mode. This is the normal operation mode of the radio. You can transmit and receive as normal. PA "Public Address" - If you hook a PA speaker to the PA jack in the back, you can mount the speaker on the out side of the vehicle, and talk over it (Its loud). Also, anything you receive over the radio when not holding the mic key, will come over the PA speaker. This is useful when you are not in the vehicle, and need to hear when some one comes on the radio.

Switch 4. BRT and DIM - this is the brightness of the meter light and channel display. BRT stands for bright.

Switch 5. Normal and CH 9, When the switch is in the normal position, everything is normal, but when you flip it up to CH 9 it instantly puts you one channel 9 with out having to turn the dial. CH 9 is the international emergency channel. So it lets you go to Channel 9 quick. when you put it back to normal it will put you on the channel you were on.

Meter explanation. - You have 3 horizontal lines on the meter. the top line is your SWR (only when in SWR mode on the switch. The next one down is you Signal going out. And the bottom one is your signal coming in, in DB's. ***Also noted that part of the SWR line has a CAL )calibration mark. When you have the switch in CAL, and key the mic, you turn the CAL knob up until the needle is at CAL triangle, and then put the radio on SWR and key it. where the needle falls, on the top line is your SWR. If it is in the red your antenna is not tuned, and you can damage your radio.


HERE IS HOW TO TUNE YOUR ANTENN:



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 12, 2010 | Cobra 29 LTD CB Radio

1 Answer

I lost my manual and I don't know how to calibrate my CB its a cobra 29Ltd chrome edition


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.

Oct 21, 2010 | Cobra 29 LTD CB Radio

1 Answer

29 LTD CB Radio: Calibrate cb radio...


The CAL is to calibrate meter for reading SWR (standing wave ratio) which is reflected power when transmitting back to receiver(radio) from antenna system.
This CAL switch position when selected and mic keyed uses the CAL knob to align the meter needle with inverted red triangle next to cal on meter. Then when you select SWR switch position meter will display accurately when mic is keyed for that channel. Now notice the difference when you go between channels 1 and 40. The ant led light will act as idiot light if it is not lit then you are most likely safe to transmit.
I say system because your vehicle, antenna and coaxial cable are all part of this system. When you have a high reading and have to trim you antenna this is really calibrating the antenna to the vehicles body which acts as a ground plane.

May 16, 2010 | Cobra 29 LTD CB Radio

1 Answer

How to set SWR readings to my K40 Antenna without a meter


If you have a cobra 29 then you have a meter. There is no way to Tune an antenna without a meter. You need a device that can read the reflect, or Standing Wave Ratio.That is a standing wave of RF energy that instead of leaving the antenna, is going back down the feed line to the radio and in time hurting the radio.

If you have a cobra 29 LTD, it has a build in SWR meter. It is not as accurate as an in line meter, but it will get it close enough not to hurt the radio. Here is how to do it.

Turn on the radio, with the antenna hooked up. Never key with out an antenna hooked up.

Set the switch all the way to the left(S/RF SWR CAL) to CAL. this stands for calibrate.

You will notice there is a knob right next to the channel selector knob marked SWR CAL as well. Start with the knob turned all the way to the left.

Put the radio on Channel 20. This is just about the middle of the band.

Key the radio and hold it. While holding the key on the mic, turn the SWR CAL knob up until the needle on the meter hits the mark "CAL". there is a triangle, and a gap in the line. The needle needs to be at the point of the triangle in the gap.

NOW, while still holding the mic key, flip the switch from CAL to SWR. You should see the needle immediately swing back. What ever the needle is on at this point is your SWR reading. use the set of numbers on the top of the meter, that's for SWR measurement.

If the needle does not swing back, and is in the rad, the antenna is WAY off. There are some reference points on the scale. The first gap in the line is 1.5 SWR. if the needle is there or less that is fine. then you have 2 and 3. 2 is not so great, but not extremely bad, but you should try to get it lower. 3 is really bad. Anything past 3 is considered infinity, and is really really bad.

If its high, then your antenna is either too long or too short. So how do you know which?

Here is how.

Turn to channel one and repeat the SWR process from above. Make note of the reading.

Then turn it to channel 40. Repeat the process again and take note of the reading.

Now, if the SWR is higher on channel 40 then 1, then your antenna is too long and you must shorten it. If the reading is higher on 1 then 40, then your antenna is too short, and you must lengthen it.

Make adjustments in length about an 1/8th inch at a time until you have either the same reading on 1 and 40 or real close, and or the reading on channel 20 is really low.

If you get it so that the reading on 1 and 40 are the same, then the SWR reading on 20 will most likely be almost nothing, unless there is either something wrong with the antenna, coax, or its just a crappy antenna.

K40 should be able to get a nice low SWR.

Apr 04, 2010 | Cobra 29 LTD CB Radio

3 Answers

Dont know how to use the swr meter on my radio


With radio turned on

1. Switch the first switch (S/RF SWR CAL) to CAL setting
2. Key mic up &
3. Turn SWR CAL knob while still keying mic until the needle is on the red CAL arrow at the far end of the meter scale. Unkey mic.
4. Switch the first switch back to SWR setting.
5. Key mic up again and record SWR reading and adjust as needed.
6. When done adjusting put switch back in the S/RF setting for normal operation.

Do not flip the switch with the mic keyed up.

Jan 19, 2010 | Cobra 29 LTD 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

2 Answers

I need the manual/s for a Cobra CB radio, 29LTD Classic,ser#105129711,manufactured 5/01. Thanks for any help you might have, This radio has a built in SWR meter and I need to know how to tune it or do I...


1) push the button marked S/RF / SWR / CAL to CAL

2) Hold in the button on the mic

3) Turn the SWR CAL knob until the needle is over set to the far right of the meter

4) flick the switch (in step 1) to SWR

Your SWR reading will be displayed. The more to the left the better..

Jun 22, 2009 | Radio Communications

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