Can anyone tell me how to wire a four pin cobra microphone to this radio? I have a spare 5 pin din plug and want to make a pigtail adapter to plug a 4 pin cobra mic into .
Thanks!
Thanks!
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Cobra 19XS
- Thread starter Van Lifeson
- Start date
Cobra standard 4 pin wiring is:
1. Shield (ground)
2. Audio
3. TX
4. RX
Cobra 19XS 5 Pin DIN wiring is:
1. Audio
2. TX
3. Shield (ground)
4. Shield (ground)
5. RX
So an adapter should be. (4 pin -> 5 pin):
1 -> 4
2 -> 1
3 -> 2
4 -> 5
You can double check that by searching for the 19XS schematic and the 40X schematic and comparing how the sockets are wired in each radio.
1. Shield (ground)
2. Audio
3. TX
4. RX
Cobra 19XS 5 Pin DIN wiring is:
1. Audio
2. TX
3. Shield (ground)
4. Shield (ground)
5. RX
So an adapter should be. (4 pin -> 5 pin):
1 -> 4
2 -> 1
3 -> 2
4 -> 5
You can double check that by searching for the 19XS schematic and the 40X schematic and comparing how the sockets are wired in each radio.
If you trace out where pin 2 connects one of the places it goes is the T/R pin (pin 20) on the PLL. High is receive, low is transmit. So any voltage that may be present on pin 2 of the DIN connector should go away when the push to talk button on the mic is pressed since you're effectively grounding it out.
Or at least I think that's what Andy was pointing to.
Yes, High - means RX mode - LOW - means TX - Low = Grounded.
So, if it floats - row with it.
Because the Service Manual shows 5-pin, but two pins are grounded - per schematic - but one is tied to the other - where? I believe the Mic socket - but this doesn't mean anything to anyone unless photos - for even the Service Manual cannot show this properly.
This is the HANDSET side (Plug)
Note - PIN 4 is not used
So, the Mic itself also needs to have 4-wire - but you really should short the same two pins - the socket would have to use for that SAME ground. That would be Pin 3 and Pin 4. In the Above graphic - they use PIN 3 on the PLUG side.
The Service manual isn't as clear on this - but to help....
The "MIC Audio" line heads to two spots. One to the main PC board, thru a RF Choke (RF201) 22uH - which is the LIVE wire itself - which feeds into a Limiter - Q106 - a PNP. It's tapped to the Collector, and also uses a Clipper D109 to help process the Audio so the limiter circuit sees positive going energy that can otherwise cause distortion.
The "other half" of these two wires is; what is interesting. It takes the AUDIO from the Receive Detect, up to it.
Why? Because of the way THAT wire is used.
Firstly 1 wire off of PIN 1 of the JACK side comes from the MIC AUDIO PLUG - PIN 1 - and routes directly to the main PCB. RF201 Choke
The 2nd wire heads up to the PA./SQ pot - which is used as a COMBINATION switch.
When the Radio is in RX mode, you power it up, ON/Volume - but you also have to make sure the PA/SQ control is not on PA mode. Anything above fully CCW is "PA OFF" - turning the PA/SQ knob fully CCW turns on PA.
The switch is a lot like the ordinary ON-VOL switch from other radio sets - but they use the switch contact side as the DPDT side that when NOT in PA mode - sends MIC audio to the RF201 Choke, and VOLUME knob then has RX on itself. SQ operates normally.
To keep the radio quieter, they route VOLUME thru R102 a 22K resistor - IN RX mode (PA off)
In PA mode - the RX VOLUME line is "Broken" - it's shifted from R102 - to RFC201 - raising the volume up - SQ is disabled so the person can control RX and MIC volume at the same knob. And you use the PA speaker jack for you to hear both RX and PA mode.
So schematically...
I'm just not sure how much help do you need?
Since @TM86 was working with you - I only wanted to inject a "yes" to help you and if you needed verification - the Service manual and all its data - schematic and drawings on where things go - is the only way to help you both in finding a common ground - here, on the forums - to do it.
Then we'd all jump in and have that sucker Cobra'd into a Cadillac - all pinstriped - plated in gold and decked out in rag-top - as a chick magnet convertible ready to roll...
So, if it floats - row with it.
Because the Service Manual shows 5-pin, but two pins are grounded - per schematic - but one is tied to the other - where? I believe the Mic socket - but this doesn't mean anything to anyone unless photos - for even the Service Manual cannot show this properly.
This is the HANDSET side (Plug)
Note - PIN 4 is not used
The Service manual isn't as clear on this - but to help....
The "MIC Audio" line heads to two spots. One to the main PC board, thru a RF Choke (RF201) 22uH - which is the LIVE wire itself - which feeds into a Limiter - Q106 - a PNP. It's tapped to the Collector, and also uses a Clipper D109 to help process the Audio so the limiter circuit sees positive going energy that can otherwise cause distortion.
The "other half" of these two wires is; what is interesting. It takes the AUDIO from the Receive Detect, up to it.
Why? Because of the way THAT wire is used.
Firstly 1 wire off of PIN 1 of the JACK side comes from the MIC AUDIO PLUG - PIN 1 - and routes directly to the main PCB. RF201 Choke
The 2nd wire heads up to the PA./SQ pot - which is used as a COMBINATION switch.
When the Radio is in RX mode, you power it up, ON/Volume - but you also have to make sure the PA/SQ control is not on PA mode. Anything above fully CCW is "PA OFF" - turning the PA/SQ knob fully CCW turns on PA.
The switch is a lot like the ordinary ON-VOL switch from other radio sets - but they use the switch contact side as the DPDT side that when NOT in PA mode - sends MIC audio to the RF201 Choke, and VOLUME knob then has RX on itself. SQ operates normally.
To keep the radio quieter, they route VOLUME thru R102 a 22K resistor - IN RX mode (PA off)
In PA mode - the RX VOLUME line is "Broken" - it's shifted from R102 - to RFC201 - raising the volume up - SQ is disabled so the person can control RX and MIC volume at the same knob. And you use the PA speaker jack for you to hear both RX and PA mode.
So schematically...
I'm just not sure how much help do you need?
We're here...
If You Need More Help...
If You Need More Help...
Then we'd all jump in and have that sucker Cobra'd into a Cadillac - all pinstriped - plated in gold and decked out in rag-top - as a chick magnet convertible ready to roll...
Last edited:
Feel free to inject any time. You've got a heck of a lot more experience than I do in the CB world.
FWIW, I happen to have a Cobra 19XS sitting here, and it has the DIN plug. I can see the wire running from pin 3 to pin 4. I'd send a pic but I have no way to jam a camera in there. These weren't exactly large radios.
No one should have a problem wiring up a 4-pin plug to dongle for the 5-pin DIN half-moon
But if TX "Dies" that is the 2nd half of that DPDT - so for some people I've know from my past that owned this radio often forgot about the PA/SQ function and many a hubby was woken up in the middle of the night with the squealing of the EXT speaker hooked up to the wrong "hole" in the back...
Mobiles, gotta' love them...
But anyhoo, the 2nd half of the switch routes power back to the Main Board from one of these Poles on the back of the SQ control. One heads off to the back panel, the other heads off to the FRONT "center" of the board and runs the regulator for TX POWER so the VCO can even send it to the TX Side. So, with the SQ control off its full - Counterclockwise Detent (Not in PA mode) - you'll see power on PIN 2 because R215 and Q201 are working - it's the only "true status" check so Q202 can even work.
The reason why I even knew this was due to getting invited over for "coffee and ..." which turned into a "Hey, take a look at this!" - which then turns into - "Did you forget to turn this SQ knob down - to the, er - not-so-far-OFF in OFF position?
Just Fun days...
But if TX "Dies" that is the 2nd half of that DPDT - so for some people I've know from my past that owned this radio often forgot about the PA/SQ function and many a hubby was woken up in the middle of the night with the squealing of the EXT speaker hooked up to the wrong "hole" in the back...
Mobiles, gotta' love them...
But anyhoo, the 2nd half of the switch routes power back to the Main Board from one of these Poles on the back of the SQ control. One heads off to the back panel, the other heads off to the FRONT "center" of the board and runs the regulator for TX POWER so the VCO can even send it to the TX Side. So, with the SQ control off its full - Counterclockwise Detent (Not in PA mode) - you'll see power on PIN 2 because R215 and Q201 are working - it's the only "true status" check so Q202 can even work.
The reason why I even knew this was due to getting invited over for "coffee and ..." which turned into a "Hey, take a look at this!" - which then turns into - "Did you forget to turn this SQ knob down - to the, er - not-so-far-OFF in OFF position?
Just Fun days...