given a cobra 19 DX II - need more info, rcvs fine cant xmit

[thebanjoman]

OK, Newbie has some very simple questions but can't seem to find the answers for.

I was given a Cobra 19 DX-11 with a Cobra model HG M77 mic and a no-name antenna. Its no prize I'm sure but I need a radio for short distance communication between vehicles during interstate drives and on the trail.

The price was right anyway

The radio receives fine but when I try and transmit the red TX light comes on but I can't seem to transmit anything, not even 25 feet away.

can somebody point me to some manuals or offer guidance to where to start testing to tell if there is something wrong with the MIC or the radio itself.

I cant even tell if this mic is wired correctly for this radio. None of the mic diagrams I have found list the 19 DX so I can't tell if it is right or not.

The package of the mic says

1 ground
2 audio out
3 transmit
4 receive

Any help would be greatly appreciated.

[BigBopper]

Cobra that you have in the attached chart is wiring#9

[thebanjoman]

thank you for the reply but the mic connector is only a 4 post, not a 5 post so it can't be diagram #9.

[jcollins]

someone must have changed the
microphone connector to a 4 pin.
it is supposed to be #9 sorry
i cant be more help
jon

[thebanjoman]

thanks for the reply.

I do not believe that the connector has been changed from a 5 pin to a 4 pin.

The radio says right on the front 19 DX II in the lower right hand corner of the face.

I'm sure the connector that came with the radio from the factory is a 4 pin. And the mic that came with it APPEARS to be wired properly

When I key the mic, the red TX light comes on so I 'THINK' that it is wired correctly, but I don't know why no sound is sent.

[Phaze91460]

Do you have a friend with a cobra radio that is working that you can borrow their mic for a test ?

[thebanjoman]

I was given 2 microphones with this radio.

The stock mic that came with it and the Cobra M77 mic. The M77 was new in box.

Both exhibit the same response.. the only thing I get out of the radio is the red TX light comes on in the front panel and that is it.

[oknaz]

Maybe it's the final's .......i would start looking around for a tech that you can trust and see what's really wrong with it .

[Phaze91460]

I would still try to rule out the mic issue. Take both of your mic's and try them on another Cobra radio and see if you can borrow a known good working mic and try on yours.

I have a D104 mic that is wired correctly and will trip the red "TX" light but wont broadcast at all. With a mobile in the same yard you cant even see a key up. Tryed it on 4 radios with the same responce.

[BigBopper]

A Royce mic will trip a cobra TX, but won't transmit,,,,just a thought

[thebanjoman]

Since I don't have anything to lose at this point I will try and take the cover off and see if there is anything that looks disconnected, discolored or broken.

Sure wish that I had more information on this radio, a schematic or anything.

For what it would take to have it looked at I would probably be better off to just get a new one.

[LordDragr]

I would reccomend that you do get a better radio. I have a Cobra DXIII in my closet and for some reason one day it just didnt work like it used to it was wierd all of a sudden the speaker got real quiet and you can barely hear anything so I go me a new and better radio.

[thebanjoman]

I'll continue to research the problem, pull the cover an see what more can be done. All I will have lost is time at this point.

The solution could be simple.

Another thing that may move me toward another radio as well is that this radio has a VERY ANNOYING QUIRK.

You power it up, it defaults to ch 9,

You change the channel, power off the radio, turn it on again...

BAM.. back to Ch 9..

Very irritating


No wonder this radio was given to me!!

[Phaze91460]

Could be !

[thebanjoman]

I spent some time this afternoon fiddling again with the radio.

1. I got 2 mics with the radio.

Aries A520 MIC - the only thing I can find out is that this is called a "cheap replacement for cobra radios"
Cobra M77 - The packaging says nothing about any "19" Cobra series radios on the box, only 21,25,29, and 148 series radios.

None of the info can tell me if I have the right wired microphone.

2. The S-RF/Power meter will display when recieving

3. When trying to transmit, ONLY the Red TX light will turn on and none of the S-RF/Power meter leds will light.

4. I had an old Radio Shack 8 Ohm PA speaker and hooked it into the radio and set the switch from CB to PA. When I key up the MIC I get a large SQUEAL out of the PA horn and I can't send hear anything out of the PA speaker. I should expect to be able to have my words come out of the speaker if the MIC is working.

I have found some info on the Net about mic wiring

[Please login or register to view this link]

This is the next step, to see if I can dig up an meter and see if I can make any more headway.

Something tells me that nether mic is wired properly for this radio and once I find out the RIGHT wiring of the mic I may be in business.

[BigBopper]

My bad it was a 4 pin from factory, you were right

[5H Outlaw]

I hope this works out for you. I've got one that's doing the same thing, waiting for my tech to get back from holidays. Keep us posted.

[thebanjoman]

Turns out the problem was the COAX cable I was using. I swapped out the COAX with a new one and radio is transmitting and working OK.

Something with the cable was allowing the radio to receive but was blocking all ability to transmit. It isn't perfect, but it is sending a decent signal.

[thebanjoman]

Turns out the problem was the COAX cable I was using. I swapped out the COAX with a new one and radio is transmitting and working OK.

Something with the cable was allowing the radio to receive but was blocking all ability to transmit. It isn't perfect, but it is sending a decent signal.

This whole story just gets better and better. I put in the new Coax cable and was transmitting OK.

FOR THAT INSTANCE.. I took the truck out on the trail and BAM.. transmit stopped working again.

I got flustered and turned the radio off when I took the truck home and forgot about it all. The truck and radio problems sat for a few months. I had other things to do and wasn't going to fight with this.

The next time I had the truck out on the trail and knew that my radio wasn't working a friend looked at the back of my truck and saw something that was very odd looking.

It looked like 'GLITTER' over the back of the truck and I never saw it before.

Well MYSTERY of the CB RADIO that would not transmit ANSWERED..

That 'GLITTER" was actually the ground up pieces of the unsheathed wick type cable that was inside the large spring at the base of the antenna.

The spring had been pulled past its limit sometime and the inside wire stretched too far and snapped itself. It then spent time being caught in the spring when it whipped around on the trail and eventually ground the wire end into dust and that is what we saw around the base of the antenna.

I can only think that somehow had the wire was making contact when it was sitting in the garage and transmit worked then. The movement of the antenna on the trail broke contact again. NO TRANSMIT

My changing the COAX cable was not the true answer to the problem. Replacing the spring with a new one and radio is working perfectly.

PROBLEM SOLVED.. So now I have a spare COAX cable, A Spare MIC and a working CB radio in my truck.

Now I can get that spot in my forehead to heal after banging it against a wall for so many months....

[Rex_foxhound]

LOL.

Glad you got it fixed.