I have a Cobra 148GTL that does not want to work with any power mic. I did get a Workman DM5000 to work for a little while. The Workman is a 4 pin so I got a 4 to 5 pin adapter and it was working but when I turn on the amp it then squeals and you get shocked by one of the inputs to inject a sound byte (it's metal) I have tryed with a 5 pin Cobra power mic same squeal with the power up no metal parts so no shock. I have run grounding wires to the cb chasis and antenna matcher with match or with out no difference. This is a base station oh and also I installed two five inch cooling fans and they stop spinning when I key up with the amp on when I unkey they start again. I am using two power supplies it doesn't matter which one they are running off of.
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Mic squeal
- Thread starter hammer0630
- Start date
really common problem with 5-4 pin converters... I wired mine interanlly and the issue went away... IE I converted it to 4 pin jack
^^^I agree, convert to 4 pin. If you are handy with a soldering iron and can read schematics, it's a straight forward conversion. Well worth the short amount of time and will save so many headaches.
How did you wire up the cooling fans?
How did you wire up the cooling fans?
No need!
Your right I don't it has unbelievable audio with a stock mic. I just wanted to see if I could get more I guess. I did clip one audio limiter if that's the reason. I believe it was #R-33 as marked on the circuit board it is has another limiter but that one if disconnected it has been said to screw up your audio on SSB. As for the Mass cool 5x5 cooling fans for the amp it's positive and ground I had it hooked up to the supply that powers the amp then I switched them to the supply that powers the 148 same thing they shut down anything over eighty watts. Now these fans are designed for such applications as this. The only thing I can think of is some how the RF is bleeding through the very small gauge wire they come with and creating chaos
Your right I don't it has unbelievable audio with a stock mic. I just wanted to see if I could get more I guess. I did clip one audio limiter if that's the reason. I believe it was #R-33 as marked on the circuit board it is has another limiter but that one if disconnected it has been said to screw up your audio on SSB. As for the Mass cool 5x5 cooling fans for the amp it's positive and ground I had it hooked up to the supply that powers the amp then I switched them to the supply that powers the 148 same thing they shut down anything over eighty watts. Now these fans are designed for such applications as this. The only thing I can think of is some how the RF is bleeding through the very small gauge wire they come with and creating chaos
I made a big mistake when I bought my first Cobra 148 in the early 1980s. Everyone was into power mics and I bought a nice Astatic 575 to use on it......well it squealed until I turned the mic almost off and the mic gain down a bit. At that point it was not even as loud as the stock mic!!!!!! These radios have heavy audio that doesn't work well at all with amplified mics.
It is very hard to find a decent stock mic any more.
Talk back
No my 148 does not have talk back. I got lucky and found a 148 built in 91 still in box a couple months ago. The Workman DM-5000 is a echo mic with talk back I had it turned nearly off. Now I can get these powe mics to work when not running power ok to very good especially the Workman.
No my 148 does not have talk back. I got lucky and found a 148 built in 91 still in box a couple months ago. The Workman DM-5000 is a echo mic with talk back I had it turned nearly off. Now I can get these powe mics to work when not running power ok to very good especially the Workman.
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