Hi everybody,
I just got hold of an early model Cobra 139xlr. Serial number 7001xxxx. It has its share of problems and I am trying to work them out. When I first got it, it had very little receive on ssb and am, mostly just some white noise. It shows modulation on the meter but not on the RF meter, I get about 1 to 2 watts out on the RF meter on ssb and nothing on am, with the exception of the modulation meter working. So I worked the controls some and it seemed to start getting better. I sprayed Deoxit on the am-ssb switch and Bang ssb jumped up real loud, but I am only hearing the loudest signals but still no movement on the RF meter, and am is still real quiet until one of the big boys at the truck stop about 5 miles from me keys up.
I have only had it a few days, but have replaced every electrolytic in it, including the power supply, but it did not help a bit.
I do know that the receiver was overloaded before I got it, guy fired up another cb in the same room and really made it squeal.
Can anyone point me to what diodes may have blown when he did this? I am waiting for a Sam's Book and am hoping it is not TR5 that went, the 1730's are not around anymore. I am going to pull this one today and check it, but am hoping for something simple like some diodes. So if someone could tell me which ones are the most likely to be affected by an overload, I would really appreciate it.
This radio is in looks a 8+ inside and out. It has some of the factory updates, at least up till my serial number.
I do not plan to mod it, just make it talk and receive like it did back in the day. Since it does not transmit, I suspect the driver or final, but I hope for better.
Any suggestions or info you can pass my way will be greatly appreciated. This is one good looking radio and I want it to work as good as it looks.
Thanks, Sammitch
I just got hold of an early model Cobra 139xlr. Serial number 7001xxxx. It has its share of problems and I am trying to work them out. When I first got it, it had very little receive on ssb and am, mostly just some white noise. It shows modulation on the meter but not on the RF meter, I get about 1 to 2 watts out on the RF meter on ssb and nothing on am, with the exception of the modulation meter working. So I worked the controls some and it seemed to start getting better. I sprayed Deoxit on the am-ssb switch and Bang ssb jumped up real loud, but I am only hearing the loudest signals but still no movement on the RF meter, and am is still real quiet until one of the big boys at the truck stop about 5 miles from me keys up.
I have only had it a few days, but have replaced every electrolytic in it, including the power supply, but it did not help a bit.
I do know that the receiver was overloaded before I got it, guy fired up another cb in the same room and really made it squeal.
Can anyone point me to what diodes may have blown when he did this? I am waiting for a Sam's Book and am hoping it is not TR5 that went, the 1730's are not around anymore. I am going to pull this one today and check it, but am hoping for something simple like some diodes. So if someone could tell me which ones are the most likely to be affected by an overload, I would really appreciate it.
This radio is in looks a 8+ inside and out. It has some of the factory updates, at least up till my serial number.
I do not plan to mod it, just make it talk and receive like it did back in the day. Since it does not transmit, I suspect the driver or final, but I hope for better.
Any suggestions or info you can pass my way will be greatly appreciated. This is one good looking radio and I want it to work as good as it looks.
Thanks, Sammitch