Cobra 29 ltd wont transmit correctly It puts out signal but the sound it transmits its all fubared The pa works Im thinking its the output modulation or an RF transistor or a bad tune Please help me check voltages Thanks

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.

look into buying a new radio. If you had researched further you would have found out that unless you are on cb your radio will not operate . If you are on PA the you can only transmit through the PA system not the cb. If you changed the audio IC then you probably did a cold solder on it. You need an external speaker to operate the pa mode and an external speaker to operate the CB mode .If you decide to fix it more it will cost you more then buying a new radio.

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.

If you're using the RFX-75 amp section. Then you'll need to make sure your transmiter section is tuned for full output. The last last unit I installed in a Cobra 29 LTD, the radio modulated right at 100 watts output.
Hope this helps,
J.R.

If the receive works ok,sounds like a mic
problem,try another mic if you can find a
buddy who has a Cobra that may let you
try it most all Cobra mic will work but not all.
Good Luck

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

Hi and welcome to FixYa,

Initially, pls confirm that there is modulation (transmit audio). The reason I asked is if IC4 (TA7222P) is blown, then the radio would have no audio amplifier which would explain no receive audio. Additionally, the final and pre-final (TR15 & 15) gets is modulated TX+12 through D8 from T1 which in turn is the output of IC4 through C48.

Perhaps a schematic diagram may be of further help.

Good luck and Thank you for using FixYa. Happy Holidays.

Hi and welcome to FixYa,

Initially, pls check the final and pre-final (TR15 & 15) and that it gets modulated TX+12 through D8 from T1 which in turn is the output of IC4 through C48.

Perhaps a schematic diagram may be of further help.

Good luck and Thank you for using FixYa. Happy Holidays.

Bad switch. It's that simple. The factory switches are crimp together junk. You may be able to use a pair of needle nosed pliers to softly squeeze the case of the switch together to correct the poor contact in side of the switch, but, if it gets a lot of use you may need to replace it altogether. Or try adjusting

Thanks!
Dodgem

http://dodgem250.angelfire.com

It sound to me like it could be your finals, as its heating up its slowly cooking itself, but you my want to to check the c12 cap as if it is not emiting the correct voltages it could be over working your finals, or under driveing it.