Question about Cobra 29 LTD CB Radio

1 Answer

I have a 29 ltd classic I calibrated it, I can receive but cant transmit. when I key up the Mic. it swings all the way to the right. My ground and ant. are both good any help is appreciated.

Posted by on

Ad

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Master
  • 438 Answers

I`m not certain how you calibrated your unit but being that i have extensive knowledge regarding radios my guess is that you do not have the necessary test gear to execute this procedure, also there is for the most part no reason to re-calibrate the RF circuit once they have been calibrated from the factory unless service has bin performed to the RF circuits ,possibly you might have tried to unlock additional channels capable bye your type unit and modified it incorrectly and your receiver frequency is not the same as the transmitted frequency, restore any modifications that you executed but and if you adjusted any coils pots,trimmers you must have some way to measure your adjustments
a calibrated signal source, a calibrated signal analyzer and RF measuring device such as a
RF what meter and field strength meter maby a oscilloscope depending what was done to the unit is necessary to perform calibrations

If you have thees or most of thees items let me know the model of your device and i will try to help you further

good luck from unit 99, power master base, Vancouver B.C 19 70s to 1978. VE7-ICV now.. Falco

Posted on Oct 15, 2013

Ad

6 Suggested Answers

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

Ad
  • 3 Answers

SOURCE: Cobra 29 LTD Classic not transmitting or receiving

ant. light should only come on if you have a high vswr a bad thing did you check that cb/pa switch is set to cb check your swr this is not a good place to mount ant. as it is close to metal of back of cab

Posted on Dec 24, 2008

  • 1 Answer

SOURCE: Cobra 29 LTD Classic not transmitting or receiving

As I understand from a tech friend of mine, most truck beds are not grounded well enough. Perhaps you could borrow/purchase a magnet mount antenna and locate it on the roof, for testing. Then you would have it narrowed down to the location.

Posted on Jan 07, 2009

  • 773 Answers

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.

Posted on Apr 24, 2009

  • 773 Answers

SOURCE: cobra 29 ltd classic antenna calibration ??

You should not calibrate the antenna before you install it on the car!! the antenna needs to be calibrated on the vehicle that it is going to be on. Type of vehicle, different mounts, and many other variables can change the amount of reflection you will get.

j0hn9999 did a much better job but left some info out.

Take your SWR readings on channel 1, then on channel 40.... NOW, if your SWR is higher on ch 40 then ch 1, then your antenna is too long and it needs to be shortened. Refer to the antenna instructions on how to shorten the antenna.

If your SWR is higher on ch 1 then on ch 40 then your antenna is too short. You must lengthen the antenna. Again refer to your antenna instructions on how to lengthen your antenna.

You must calibrate each time you take a reading.

Make sure your doors and windows are shut when taking a reading

Make sure you are in an open lot when taking a reading as buildings, trees and other structures can cause reflection and give you an inaccurate reading.

If you adjust the length of your antenna on another vehicle and then put it on yours, the SWR will be off. It will need to be tuned again.

An external meter is better then the one in the radio, but will need to be hooked up in the vehicle you have the antenna on.

If you are not running any kind of power, or do not have a swing kit installed, and the radio is stock, the meter in the radio is more then enough to get a correct SWR reading.

Posted on Apr 24, 2009

riceski
  • 1851 Answers

SOURCE: 29 ltd classic wont transmit

Hi,
Great radio when it works.
If you have your settings on CB - not PA - -be sure that your Cobra has that setting selected.
If CB -is selected and still nothing - be sure you have a working mic. These wires are fragile and can break internally. One easy way to check is to borrow a cobra mic or even drop by a CB repair shop and ask them to do a mic check with the mic - it is free.

If you have a bad mic replace it and all should be well.
If your mic is good and it still doesn't transmit you will need to replace the finals in the unit. It is common that these burn out of you got too close to someone with too powerful a radio. The CB shop will need to look at it further and repairs should not be over about 40.00.

Good luck with your Cobra.

Posted on Mar 31, 2010

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

Cobra 29 ltd classic year 2004. rf gain problems.


Put SWR meter between your antenna and output, test wave length receive/transmit, might need a ground plane or center loaded stick.
Could be transceiver relay, try clicking mic fast, it should click out as fast as you key the mic.

Oct 26, 2016 | Cobra Radio Communications

1 Answer

The calibrate needle wont move to the right to set whe trying to calibrate on cobra 29 ltd classic new radio


You have to press the transmit button to get the radio to send a signal that you can calibrate the SWR meter to. If you are pressing the transmit button and nothing is happening then it could be a blown final transistor, a bad switch, bad microphone connection etc.

Jul 05, 2014 | Cobra 29 LTD CB Radio

1 Answer

When i try to calibrate my cobra 29 ltd classic the needle will not go to the right


make sure you have your radio set on CAL and then adjust the knob that says adjust .Turn it all the to the right then bring it back to the set point on the dial then un key the mic,move the switch to SWR , key the mic and that is your reading. Do this on channels 40 - 1 then 19. Make sure you write down the readings for each channel. The adjust your antenna from there.

Jul 05, 2014 | Cobra 29 LTD CB Radio

1 Answer

I can hear everyone talk to me but i cant transmit to them,they can hear me key up but no voice to them.i have checked all connections and grounds,still the same.


Mic may have audio wire broken in cord at mic plug wire solder connection.
Stock
1- Shield
2- Audio
3- Transmit
4- Receive

notice the numbers on the black plug after you pull it out of the radio.

Sep 12, 2011 | 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

I have a cobra 25 ltd and when i key the mic the gauge of the db barley goes up. is something wrong ? also the gauge says its measuring tx power what does that actually mean/ do


TX means transmit. There are 3 settings for the meter. The top one is to measure your TX/RX that's transmit and receive. CAL is to calibrate the meter to check your SWR.

Reasons your needle may not be moving much when you key while on TX/RX. The dynamic is probably all the way down. That is your mic gain. If you turn that up when you talk the needle will swing more. If the radio is stock and not modded, you can turn this all the way up and leave it.

Also there could be something wrong with the mic. If people can hear you then its not the mic.

If people can hear you fine when you transmit, it may just be a bad meter. Not a big problem, you will just need an external meter to make sure you swr is not high.this is important because if it is over 1.5 you run the risk of blowing the final transistor.

Oct 11, 2009 | Cobra 29 LTD CB Radio

1 Answer

Cobra 29 ltd classic cb not transmitting


Check the ground. Make sure its grounded well on bare metal. To see if the ground is bad, or not making good connection, disconnect the antenna and turn it on. if it does not power up, that means your ground is bad, and it was grounding only through the antenna.

Make sure not to key up with out the antenna connected.

Dec 24, 2008 | Cobra 29 LTD CB Radio

1 Answer

Cobra 29 LTD Classic not transmitting or receiving


ant. light should only come on if you have a high vswr a bad thing did you check that cb/pa switch is set to cb check your swr this is not a good place to mount ant. as it is close to metal of back of cab

Dec 20, 2008 | Cobra 29 LTD CB Radio

1 Answer

Cobra 29 LTD Classic not transmitting or receiving


As I understand from a tech friend of mine, most truck beds are not grounded well enough. Perhaps you could borrow/purchase a magnet mount antenna and locate it on the roof, for testing. Then you would have it narrowed down to the location.

Dec 05, 2008 | Cobra 29 LTD CB Radio

Not finding what you are looking for?
Cobra 29 LTD CB Radio Logo

58 people viewed this question

Ask a Question

Usually answered in minutes!

Top Cobra Radio Communications Experts

AnyMHz.com
AnyMHz.com

Level 2 Expert

500 Answers

Steve

Level 3 Expert

3287 Answers

Brad Brown

Level 3 Expert

15628 Answers

Are you a Cobra Radio Communication Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...