Question: Re-wiring an adapter for an Astatic 636L mike for a Cobra 142 GTL Base Station

[glenn11209]

Wires, not "wites.." lol

 

[ThomasB3131]

I do not have a multimeter which is ine reason I posted this thread. What does help is your suggestion that I figure out which wites to alternate on the 4 pin side of the adapter alone.

I will reverse red and black and see what happens.

Yeah you should be good on the 5 pin side, just try and flip around some of the wires on the 4 pin side.

 

[glenn11209]

Thank you! I will let you know the results!

 

[ThomasB3131]

This is the normal mic wiring for most CB radios. It might not be the same for radio shacks

 

[ThomasB3131]

This is the wiring for the 142gtl. Now you can just match up the the wires to the right pins on the 4 pin side. I hope this helps. Let me know if you need any more help.

 

[glenn11209]

I don't know what else to do. I cannot figure out this whatsoever.

 

[glenn11209]

View attachment 79724

Thank you Thomas but that does not help. I need someone to be able to figure out which wire goes where on the 4 pin side of the adapter.

 

[glenn11209]

I am just going to but a stock mike that fits a Cobra 142 GTL. Its crazy I cannot figure out a three wire configuration no matter how many times I try touch each lead on the 4 pin end of the adapter! No transmit. I can get audio.

 

[K4EET]

glenn11209, a digital multimeter should be in your toolbox if you are going to do this type of work. Even an inexpensive one will suffice for continuity checking and basic resistance/voltage/DC current measurements that do not have to be super accurate. Here is one I found on Amazon that fits that bill for just over $10. With a multimeter, my question as to whether or not pins 2 and 4 of the Cobra's microphone connector are actually shorted could be answered. Looking at the schematic diagram of the Cobra transceiver indicates that the two are isolated from one another. Using the Adapter with those two pins shorted may cause the transceiver to malfunction.

Cobra 142GTL Schematic

http://www.cbtricks.com/radios/cobra/142gtl/graphics/cobra_142gtl_main_sch_b_size.pdf

Etekcity Multimeter Picture

https://www.amazon.com/Etekcity-Multimeter-MSR-R500-Electronic-Multimeters/dp/B01N9QW620/

 

[K4EET]

I am just going to but a stock mike that fits a Cobra 142 GTL. Its crazy I cannot figure out a three wire configuration no matter how many times I try touch each lead on the 4 pin end of the adapter! No transmit. I can get audio.

My post #16 in this thread is the wiring configuration for the Adapter although there is the question about shorting the ground and shield since Cobra has them isolated. The Adapter would need a minimum of 4 wires and 1 jumper per my post #16. There is no way that having only 3 wires inside the Adapter would work.

Let me ask, glenn11209 do you understand what I am saying in post #16?

Using that information, the Adapter would need to be wired to accomplish that signal routing. The only caution/concern that I have is connecting the shield to ground. I do not know how the Cobra transceiver is going to react to that configuration.

Dave

 

[K4EET]

View attachment 79724

This is the wiring for the 142gtl. Now you can just match up the the wires to the right pins on the 4 pin side. I hope this helps. Let me know if you need any more help.

Thomas, looking at the schematic for the Cobra 142GTL and the wiring for the Cobra microphone (page 18 of the manual), where you have "not needed" is actually the shield connection which appears to be isolated from chassis ground. Further, it appears that this signal path is required for "something" that is switched by the microphone's PTT button. You may want to take a look at that signal path too.

Schematic of Cobra 142GTL

http://www.cbtricks.com/radios/cobra/142gtl/graphics/cobra_142gtl_main_sch_b_size.pdf

Manual for Cobra 142GTL

http://www.cbtricks.com/radios/cobra/142gtl/graphics/cobra_142gtl_om.pdf

We need a multimeter to see if that shield is tied to ground. LOL!

Cheers! Dave

 

[glenn11209]

Thank you Dave. I will give it another shot tomorrow. Thanks for all your assistance.

 

[K4EET]

Thank you Dave. I will give it another shot tomorrow. Thanks for all your assistance.

You are very much welcome, Glenn. I would like for Thomas to take a look at my conclusion as well because I am not the smartest cookie in the world. LOL! I have had a bunch of mini-strokes and that severely affects my thought processes. I do my best... Dave

 

[glenn11209]

Ok that would be great. All I need to know is what color wires go where and what number shield and ground go together.

 

[glenn11209]

I found this in regards to the Astatic mike. I am not able to figure out how to properly attache the wires on the adapter on the 4 pin side. I need someone to figure it out for me since I do not have a multi meter!

 

[K4EET]

glenn11209, let's wait for ThomasB3131 to chime back in. OK?

 

[glenn11209]

Absolutely. Thank you.

 

[ThomasB3131]

You are very much welcome, Glenn. I would like for Thomas to take a look at my conclusion as well because I am not the smartest cookie in the world. LOL! I have had a bunch of mini-strokes and that severely affects my thought processes. I do my best... Dave

I'll have to check it. When I rewired my mic for my uniden grant it was not needed, but it might be different for the 142gtl.

 

[ThomasB3131]

The wiring on the four pin side of the adapter depends on what the wiring for the other radio is. How many wires are inside the adapter?

 

[ThomasB3131]

There needs to be at least 4 wires inside the adapter for it to work correctly. The other radio is a realistic trc-221 handheld radio, correct?