Question about Cobra 29 LTD CB Radio

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Swr meter doesn't work. speaker pops

I PULLED THIS OLD RADIO OUT OF ANOTHER VEHICLE. EVERYTHING SEEMS OK EXCEPT THE SWR METER DOESN'R BUDGE. ALSO, WHEN I KEY THE MIC, THERE IS A LOUD POP WHEN I LET GO. ANY IDEAS?

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Replace the meter and speaker.

There is always a bump kind of noise when you unkey. If its popping, then the speaker is probably blown. Plug an external speaker into it and see if it is still a pop, instead of a bump.

Meters go. If tapping it while keying doesn't release it, then just replace it or just don't worry about it and get an external meter.

Posted on Apr 24, 2009

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Have a new cobra 29lx. Everthing works fine except for the SWR meter. Can't use the meter to adjust SWR. No matter what I do the meter stays the same. Sent to factory but they said nothing was wro


The SWR cannot be changed by rotating this knob. The SWR function allows you to determine the SWR or "match" of the antenna system and transmitter on a specific channel. The entire process must be performed whenever you want to know what the SWR is on a different channel. The SWR/CAL button toggles the meter between the CALIBRATE and SWR modes.
Set the radio to CH1. Press the SWR/CAL button. The radio CAL(ibrate) mode is now selected. Press and hold the mic PTT (or push to talk) button. Rotate the SWR knob as needed to adjust the meter indicator until it is on the SET mark on the dial. The meter is now calibrated for this channel.

While still holding down the mic PTT, press and release the S/RF SWR CAL button to the SWR setting to read the SWR on the meter.



This entire process should be done for Ch 20 and Ch 40. You must go through the CAL procedure for EACH channel before attempting to read the SWR.


Changing the SWR requires that the antenna be lengthened or shortened until such time that the SWR can be reduced no further. Typical SWR across the band may be:


CH1 - 1.5:1, CH20 - 1.1:1, CH40 1.5:1


or


CH1 - 2.2:1, CH20 - 1.7:1, CH40 2.3:1


The "dip" in SWR on CH20 is typical, as the antenna is the perfect length on only one channel - it will be come slightly too long or slightly too short as you tune up or down from CH20. The further away from CH20 you go, the poorer the SWR will be. You can "slide" the dip to any channel you prefer - say CH8. If you tune for lowest SWR on CH8, You might see CH1 with a 1.2:1 SWR, CH8 at 1.1:1 SWR and CH40 at 2.5:1. All are acceptable - sort of. Many manufacturers say up to 2.5:1 or even 3.0:1 matches are ok, There's no reason a quality antenna can't be tuned for optimum SWR in the middle of the band (CH20) to have less than a 2.0:1 SWR on CH1 or CH40, unless there is a ground issues or bad cable / antenna / connection somewhere.


You can view the manual here. I hope this helps & good luck!

Nov 30, 2012 | Cobra 29 Lx Full-featured Cb Radio

1 Answer

It says cb atanna warning when i key the mic. i have a new cable and new atannas as of 20 min ago. what is the problem


The problem is you need to tune the 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 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.

Aug 10, 2011 | Cobra Radio Communications

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 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

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

2 Answers

My Meter Won't Move


weather can effect your meter .Those meters are not very accurate just a base line get a good swr meter and then check it.If your getting good radio checks it could be the potentoimeter is dirty . Radio shack sells contact cleaner and lube try cleaning it . That might help

Jan 08, 2008 | Cobra 29 LTD CB Radio

2 Answers

SWR calibration waaay off the chart


You are using an inline swr meter to set your swr right, not looking at the meter on the radio? Here is the process to set swr on an antenna:

You must have an inline swr meter, which can be purchased online or from a truck stop. The ones at truck stops are cheap ones, but will do the trick for the most part.

You connect your antenna 18ft coax to the antenna plug of the swr meter, and a jumper coax (any length) to the transmitter plug of the swr meter and then to the radio.

Close all doors and make sure no one is messing around with the vehicle or antenna. You must be set up as you would normally be transmitting.

Now set your cb radio to channel 40 and your swr meter to fwd. Key up your microphone1.gif and at the same time turn the set knob on the swr meter until the needle is at the line that reads set. Unkey your mic and set the the swr meter to ref. Key up again and note what your reading is. Now leave the swr meter in ref and turn the cb to channel 1. Key up and take your reading. If the reading on ch 1 is higher than ch 40 you must raise the stinger on your antenna. If ch 1 is lower than 40, you lower your stinger. You are trying to get lower than a reading of 3 and as close to 1.5 as possible. If you lower your stinger as far into the antenna as it will go and you need it shorter, you cut the bottom of your stinger no more than 1/2" at a time, and recheck your swr reading after each cut.

Once you have gotten the best reading you can, connect your antenna directly back to the radio.

The setting of your swrs is to make your antenna as efficient as possible, by trying to get it as close as you can to a 50ohm impedance. THE ONLY PART OF YOUR SYSTEM THAT CAN CHANGE YOUR SWR IS YOUR ANTENNA, not your coax and not your radio. Your radio and coax can give you false readings, but only the antenna can actually change the swr.

On the swr meter, the fwd/ref switch stands for forward (power that is being transmitted out) and reflected (power that is reflected back into the radio.

Just for information sake, the swr cal switch on your radio is used to set the meter to reflect the swr that your antenna is set at. The meter on your radio is like a dummy light on your car. ONCE AGAIN, YOU CAN NOT SET YOUR SWR ON YOUR RADIO, only the antenna.

Dec 29, 2007 | Connex 3300 240-Channels Base CB Radio

3 Answers

Connex 3300hp radio


Hi,

Based on your post/description:

1. how do i set the swr
Normally SWR are calibrated on your operating channel (where you usually stand-by). This is to maximize transmit power and receive sensitivity. To set SWR, switch to channel of your choice, switch SWR control to CAL, key or press PTT, while pressing PTT rotate ADJ knob until max deflection of needle on meter, release mic, switch control to SWR, key/press PTT, needle reading/deflection is SWR for that channel.

I would suspect that your SWR will vary from your current 1.4. This is because you have too big excursion of channels (240 channels).

2.reading a 1.4
This reading is good enough and should do. However as earlier stated, you seem to have 240 channels which would mean that your radio + antenna moves in a wide bandwidth and since the antenna tuning is affected by frequency, your SWR will also be affected by channel.

Best if you can further lower it down.

3. some cb cant get me
This is because the standard CB radio is only 40 channels. The next would be a 80 channel and then 120 channels.

4. is it my radio
Yes, you have a wide coverage radio almost an extended 10 meter rig.

5. do i have to set my radio on high or low to set my swr
I will assume you are referring to power output, set it to HIGH when doing SWR calibration

Hope this be of some help/idea. Pls post back how things turned up or should you need additional information.

Good luck and kind regards.

Nov 08, 2007 | Connex 3300 240-Channels Base CB Radio

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