Cobra 29 LTD CB Radio Logo

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Anonymous Posted on Aug 29, 2009

I have a Cobra 29 NW LTD Classic I have power going to radio but no power when i turn on knob. i have looked inside for a fuse but can not find one.

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Anonymous

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  • Posted on Aug 29, 2009
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Did you look for power comming out of your power switch....
dont tell me that you hooked it up backwards. if you did check the imput diodes

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  • Posted on Aug 30, 2009
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Look at the power supply cord and the fuse should be there or you can straight wire it without the fuse if you can't get it to work or you can add your own fuse to the power cord if you need one.

I have a cobra too and mine is straight wired and it works just as good with out the fuse.

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Anonymous

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  • Posted on Apr 24, 2009

SOURCE: cobra 29 ltd classic antenna calibration ??

Wow. That's not at all a solution to what this guy is asking. And why all the caps??

The one point jm77437 has that is correct is that you do not set the radio, you set the antenna. The rest is blah blah.

Here is how you tune your antenna for you radio. First off it depends on what kind of antenna you have. most fiberglass antennas have a tunable tip to adjust the height of the antenna. Metal whips either have a collar at the base that the whip will either slide up or down in to adjust the height. The other type of metal whip's you have to physically clip to shorten the antenna, you must be careful with this type because once its clipped, that's it. You cannot add what you cut off.

I am going to give this example using a metal whip with an adjustable collar.

First after your radio is hooked up in the vehicle, drive to an open lot. Buildings and other structures can cause extra reflection. turn to channel 1. Flip the meter to CAL. Key the mic without talking. Now turn the CAL knob up until the needle reaches the little upside down triangle all the way to the right marked CAL. Now you have just celebrated your radio for your setup to measure you SWR. Now while still holding the key, flip the meter switch to SWR. The needle will move, and where it stops is your SWR reading. The lower the better. Anything under 1.5 is considered really good. But still, the lower the better.

Make note of what your SWR was on ch 1.

Now flip to channel 40. Repeat the SWR process. You must recalabrate each time you take a reading.

Now like jm77437 said. If your SWR reading is higher on 40 then 1, then your antenna is too long, and you must make it shorter. Loosen the collar and lower the antenna in the collar 1/4 inch at a time. check the swr each time you adjust the antenna.

If your SWR reading is higher on channel 1, then your antenna is too short. You must make your antenna longer. Do this by loossening the collar and pulling the antenna upward in the collar 1/4 inch at a time, again checking the swr each time you adjust the antenna.

What you want to achieve is having the same SWR reading on channel 1 and 40. then you have the best match you are going to get with that antenna.

If your swr is under 1.5 on all channels, you don't need to fuss unless you are a perfectionist. then by all means go ahead.

If your reading is higher then 3, or your ant light comes on, something is really wrong. Make sure your antenna is connected all the way, and the coax is not damaged.

Its important to have an appropriate SWR because if you do not, you are reflecting too much signal back into the radio, and eventually you will burn out your final transistor, and your radio will be toast.

Some tips: make sure you check the swr with the doors and windows shut. Make sure you are in an open lot. Remember to calabrate ecah time you take a reading. If you have had your radio peaked by a radio shop, and they have lowered your dead key, or have done a swing modification, then the meter in your radio will not work when taking an SWR reading and you will have to use an external meter.

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Related Questions:

0helpful
1answer

I disconnected and reconnected the cobra 29 nw ltd classic and now my voice is heard very low and slow it was working fine just before disconnection. can you help

How did you disconnect it?? Antenna wire?? Power supply?? Microphone?? May be that you have a short in your coax in back of radio. Try taking it loose and screw it back in. Try new coax. Turn up Mic gain knob or change microphone. Make sure power wires are connected RED to RED(+) and Black to Black(-). Try grounding radio to metal ; if inside house ground to metal water pipes, filing cabinet, breaker box or meter box or 8 foot rod into earth. Measure SWR it should read 1.1 to 1.5. Measure power supply with Voltmeter it should be 12 to 15 volts. Check antenna plug in back of radio is my guess or microphone itself.
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HI I AM TRYING TO FIX MY 29 COBRA LTD IT WENT OUT ON ME
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I want to calibrate my cobra 29 NW Ltd. Classic

Calibrate For SWR (Standing Wave Ratio) http://www.cbtricks.com/radios/cobra/29ltd_bt/graphics/cobra_29ltd_bt_om.pdf
The CAL is only to calibrate meter for a swr check of you antenna system it does not calibrate radio.
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Cobra 29 ltd classic will not power up

Hi pig pen, my name is John. Welcome to FixYa. Check that the in line fuse is not blowed. Make sure that you are getting power to the unit, and that it is grounded good. Let me know if you need more help from this point,and I will post the solution here. Thanks for choosing FixYa...John
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Where and what does the fuse look like for the Cobra 29LTD Classic, and is there a fuse #.

Hi, my name is John. Welcome to Fixya. You should find the fuse inside the fuse holder located on the red wire going to power source. Push and turn counter-clockwise to expose the fuse. the number and amps are stamped on the end of the fuse. Thanks for choosing Fixya.......John
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I have cobra 29 ltd has power going into radio but wont com on when you turn power knob

remove the outer casing, there is a glass fuse..( 1.5 amp )....it has probably blown
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I have a cobra 29 nw ltd classic i cannot hear or be heared

Start with the antenna that you have hooked to it, is it grounded, is the coax in good shape, is the connector in good shape. stuff like that.
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Cobra 29 issues

Check D23 and D28. They are polarity protection diodes. It could also be the power knob.
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Cobra 29 ltd nw classic

Yes, Do Not Turn Up Too 500's Way Too Dangerous, The Problem Might Be That Inside Some Cords May Be Rubbing Wrong Or, You Have A Short Cord, If Not Any Of That It Is Probally Broke
1helpful
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29 help

hi, sounds like you have a problem with the SWR' S Probably too high. Tumbleweed01
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