Question about Cobra 29 LTD CB Radio

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Just want know how to peak the power back up on my 29 ltd classic. its only putting out 2 watts on ch. 20 I suspect someone had a linnear on it prior.

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  • p_w_man81 Oct 09, 2009

    Im ok id say but i have some things off the web but just want be sure about what im doing. So do i adjust those with a power meter attached to see what it is doing. And will it effect the clearity of the radio? And what kind of power can i expect out of it

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  • 23 Answers

Just tune L10,L9,L8 for maximum.

How electronically able are you?
I can tell you how to do what most call the super modulation mod, it isn't too hard and isn't very expensive. (Unless you take it to a CB shop!)

Posted on Oct 09, 2009

Testimonial: "Please give more info on this. I would like to know all i can before i do anything to it and do i adjust these with a meter attached. Please advise"

  • davegunman Nov 04, 2009

    It can be done with a good power meter, but to do it "properly' takes some expensive equipment and the technical service manual.

    If you put a good power meter on it and adjust those components I indicated, you will see the results on the meter. When I used to do this I adjusted for maximum and then came down just a bit so as not to "stress" the components in the circuit and burn something out.




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2 Answers

Got a cobra 29 ltd classic dead keys 10 watts and swings back to 6 watts on an external meter any answers


Hi you have to make sure your antenna has 1:1 SWR reading improper use of antennas deplete the Effective radiating Power of Transmitting equipment such as the CB radio.

Mar 15, 2016 | Cobra Radio Communications

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Is there any video that i could view how to calibrate 29 ltd classic


Unless you have access to a signal generator, frequency counter and watt/modulation meter or know someone that has this equipment, do not try to do what is called an ALIGNMENT. This kind of work should only be done by someone that holds a radio-telephone repair license. A ham operator holding a technician class license or higher can also do this.

Jan 08, 2012 | Cobra 29 LTD CB Radio

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Cobra 29 ltd classic has no key watts


Not sure why you removed a resistor, but apparently it was needed in order to make the radio transmit properly. Put the resistor back in, or a new one of the same value. If you don't know the required value (because it was fried, etc.), I'd recomend bringing it to a shop, as there is most likely something else wrong with the unit.

If you really want to try and repair it yourself, and don't know the value, check out the schematics at the link below; just be sure that you are looking at the schematics that pertain to your radio, as there are a number of different versions of the Cobra 29.

Cobra 29 - CBTRICKS.COM

Oct 27, 2011 | Cobra 29 LTD CB Radio

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Not enough audio and i dont want a power mic i


Take off the cover, you will need a watt meter or mod meter to do this. On the circuit board, part side up, look for D11, and cut one end of it, hook up meter, key the mike and with a peaking or tuning tool, while saying aaahhhhhhh in a long and steady voice, tune L12,L13,L14 for highest peak, you can get the tool there also..put cover back on and enjoy.....hope this helps...

Jun 03, 2010 | Cobra 29 LTD CB Radio

1 Answer

Cobra 29 classic "swing kit" ?


A swing kit is nothing more then a Cap and a resistor. There really isn't a different way to do a swing kit, unless you do variable power, which you don't need unless you are going to run a linear, and even then you can just set the dead key with a swing kit.

you need a watt meter, preferably one that reads peak and average watts. If not, average will be find.

Open the bottom cover of the radio. Hook the radio up to the watt meter, use a dummy load or have it hooked to the antenna. Never key the radio with an antenna or a dummy load.

Find VR4. Its toward the back right of the radio. Turn it all the way to the left. That increases your modulation.

Next find L14. it is at the back in front of the final resistor. While making a steady sound into the radio, just make an ahhhhhhh noise. Back the slug out of the tank until the needle hits peak. Don't move it out any more or you will over bias the final.

Now you will need a 220 uf electrolytic cap, and a 100 ohm 1/2 watt resistor, both of which you can get from radio shack. (this is your swing kit.

To the right of the tank slug is a jumper maked JP36. Us soldering wick to remove the solder and pull out the jumper. Now put the cap in it with the stripe facing the back of the radio.(that is very important. the other way you will blow the radio.) Solder it in place and cut the extra leads off. Now on the back of the board were you soldered in the cap, solder the 100 ohm resistor in between the 2 points.

The amount of resistance determines you dead key. you will be at about a 2 watt dead key which is good for swing and if you want to run a linear. The higher the resistor the lower the dead key, and the lower the cap, the higher the dead key.

That is your basic peak and tune with a swing kit.


Dec 23, 2009 | Cobra 29 LTD CB Radio

2 Answers

How do you tune and peak a cobra 29 ltd classic and how many watts will it put out after it is tunned and peaked


i would highly suggest you take it to a cb shop to get a cb tuned and peaked. before you do that though, make sure you have a good antenna system. a good antenna will have a much greater effect on your cb than tuning and peaking. as far as output, who knows? it all depends on the skill of the person doing the tuning. be warned that any output over 4 watts is illegal and you could recieve hefty fines if caught with an illegal radio.

Sep 23, 2009 | Cobra 29 LTD CB Radio

2 Answers

I also have another cobra 29 ltd classic and it works fine but i cant talk or hear what other factory cb's can hear, it is supposed to be tuned and peaked and i have a wilson 2,000 antenna, and i cant talk...


nearly all problems are caused by poorly tuned or untuned antennas. a good antenna system with a cheap stock radio will out perform a great tuned radio with a bad antenna system any day of the week. if you dont believe me, check the firestik antenna website's tech notes. or wilson's tech notes.

Sep 23, 2009 | Cobra 29 LTD CB Radio

2 Answers

Cobra 29 ltd classic ant light


Your SWR is probably NOT fine. You need to use an external meter if you have had work done to the radio. Especially if you have had a swing mod done to the radio. When you do this, the dead key of the radio is lower then the calibration knob on the radio can adjust for. It will always come up lower then it actually is.

Your radio might have been fine before the work was done on it because it was putting out very little power. Now you are most likely putting out 50 watts or more. Big jump from 4 watts.

When your raise the power in a radio, you will notice more when the antenna is not properly tuned.

In most cases with a stock CB, even when the antenna is not even near tuned, you will get a reading less then 1.5 anyway.

the more power you put out, the more important it is to have a good match.

But an external SWR meter, and check it. be careful if the ANT light is on.

You might also want to check your coax, connections to it, and your antenna for anything wrong.

Apr 22, 2009 | Cobra 29 LTD CB Radio

1 Answer

Cobra 29 Ltd


Hi,

Appreciate the direct "Ask Me" again.

The initial posting would still hold true, best would be:
  • remove TR18;
  • replace 2SC2069 with 2SC1969; and
  • adjust L12, 13 & 14.
Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.

Good luck and kind regards. Thank you for using FixYa.

Sep 07, 2008 | Cobra 29 LTD CB Radio

2 Answers

Cobra 29 Ltd Classic


In most cases just turning up VR4 is more then enough. Replacing the final, tr14 with another transistor requires changing many more parts to get it to work.

With a new 29, there is no need to change the final. Just turn vr4 all the way up and you will see around 20 - 25 watts. L13 won't gain you a single watt. L12 will raise the dead key, and usually you want a lower dead key for good swing. L14 will gain you a few watts, but don't adjust this unless you have a watt meter. You turn it out to increase wattage, but too much will over bias the final and shorten its life.

You hook it to a watt meter with a dummy load. Then say a steady AHHHH into the mic while keyed. Turn the slug out until the needle stops going up, then back it down to where it stopped.

The easy thing to do, and you will be pleased is just to turn VR4 up. Now, Up is counter clockwise. Its a variable resistor, so the less resistance, the more modulation. So you want to turn the VR down.

that will be more then enough.

Sep 06, 2008 | Cobra 29 LTD CB Radio

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