140 gtl has no dead key no tx audio and no tx light pa works,all works. No ssb or am tx plz help

Cobra 29 LTD doesn't have SSB. You must have a Cobra 146 GTL or one of the Cobra 148 GTL's.

final

OK bare with me now i have no idea of your knowledge level with CB/ SSB radios.
Lets make sure our setting on radio face is correct before we decide this is an mechanical problem.
Set the following

• Volume knob 12 o'clock
• Dynamike knob 12 o'clock
• Squelch full counter clockwise
• Rf gain full clockwise
• Select S/RF position on the SWR/CAL switch
• Select AM position on the USB/AM/LSB switch
• Select CB on the CB/PA switch

Now there will be some critics with opinions on the next instructions. Place a small screwdriver or test lead from a multimeter in center conductor of antenna jack listen for onair noise or radios operators to verify RX is working. Now remove the antenna/screwdrive/testlead. Then key mic just long enough to notice if the meter is swinging do not hold the mic button long this can damage the final. I tell you to do it this way rather that connected to your antenna system so we can eliminate the question if it is you antenna sytem or the radio.
If the LSB or USB was selected when you keyed the mic you would see no meter movement this is due to the lack of a deadkey or carrier for SSB which is a much more efficient method of transmitting on AM.
There are few things that affected the rx and tx together.

Hi
try replacing the transistor just before the last on the rf pa output.

Hope this helps

Ray

Hi and welcome to FixYa,

Initially, the speaker of course has been checked?

Offhand, would partial schematic of the mic and speaker section help?



Good luck and thank you for asking FixYa.

How are you testing the audio out?
Are you using another radio?
If so, are you REALLY sure the other radio is ok?
If the other radio is ok, how do you know the mic is ok? have you tested it with another radio?
If the mic is ok, id have a look at the mic socket to check that all the pins are still there. Then open the radio up and check the socket is still connected to the main board.

Let me know how you get on..
M3ODQ

make sure that the rf gain is turned up all the way.Check diodes D-12&D-13.

check voltage regulator

Your problem is a faulty changeover relay on the circuit board. It is a small black device , and may have the brand name MRATA
etched on it (the switchover contact points are stuck together)
WORTH A TRY GOOD LUCK
[email protected]

No audio out / low audio out....This is a constant problem with the COBRA 148 gtl....to get a good level of volume replace the
electro caps ...start around the two speaker wires and work back from there. I'm in the process of rebuilding a 148 gtl and have found caps that are leaky and dried out...after replacing nine the volume went up to a good level...now i need to fix the distortion
and background hash. Did you know that there are many posts
on FIXYA about this same problem I.E. great TX , great PA but poor , or no audio out. these sets have been made in sevetal countries...The sets made in Taiwan or China have poor quality
front panel pots (the carbon track is micro thin and simply wares through to the material the track is printed on) This has the same effect as removing a wire from a pot I.E. no audio. The good news is that 99% of parts in the radio are freely available and that includes the front panel controls. ONE WONDERS IF THE SET IS WORTH THE EFFORT !!!

CHEERS GUYS / GIRLS.