i have a issue with my cobra 139 23 channel

[Double R]

i have a issue with my cobra 139 23 channel , its been converted to do 40 channel , i can transmit , it show mod on the radio metter , but if i put a extel meter in line it dont move the needles on it , i dont here , what i normaly here on my cobra 29 , idk what the deal is with this old base love to get it fix any ideas let me know.

 

[Atlasta]

When the meter is in line does it still show output on the radio meters? I assume you have received on-air reports both with and without the meter. Were you in AM or SSB mode when looking at the external meter? A dead key on SSB won't show any output at all. Check the mode switch.

BTW, what type of meter is it? If it's one of those multifunction meters are you certain it is in the right mode? Are you certain that the jumper cable between the radio and meter is ok? Maybe you accidentally hooked it up backwards?

Not trying to insult you but these are the first things that come to mind. Good luck, and if you need any parts for that old 139 I have a complete unit that I'll let go cheap.

 

[Double R]

i have tryed Both this 139 23 channel had the 40 channel conversion done on it , the old man i got it from had a 300 watt plug in wall linear hook too it and may have blew something up , i dont get any reseve at all it modulates on the meter on the radio but it wont show any thing on my other meter , but i think the finals are blown out it it , when i start it up it smells of solder really bad , idk any though to you guys

 

[Double R]

the in line meter works great tested it on my cobra 29 in the same day as well ,

 

[Double R]

I was also wanting to know if any one had done these radios in mossfet finals yet

 

[ExitThirteen]

I have successfully done the MOSFET final conversion on the Cobra 139 23 ch. radios. I have a Midland 13-893 23 ch. modded to go to 27.555 that runs the same board. Works quite well.

Sounds like you probably huffed the final from the amp somehow. Wish I had the radio in front of me to confirm the problem, before I tell you to start digging into stuff that may not be causing an issue. If you can confirm it's the final, I can help you with that.


~Cheers~

 

[Double R]

well i get modulation on the radio it self the relay works and the modulation works on the mod meter on front on the radio but it wont make the in line meter move at all , i cant here Any one at all , i wish i new the issue , i like to know more on the moss fet conversion on the 139 if you would explain throw Pm i would appreciate it , and do you use mossfet irf 510's or the 520s to do the conversion

 

[ExitThirteen]

You have no receive either?


Sounds like you have something else going on besides a blown final. I'd check under the board and look for any burned traces, sounds like you might have popped a trace, or the relay is messed up in some manner. Do that and let us know how you get on.



~Cheers~

 

[Double R]

i have look at the board nothing burned the finals arnt burned ether idk what the deal is .

 

[ExitThirteen]

Unfortunately, without having the radio in front of me to localize the problem makes it tough to pinpoint your fault. Do you get static or anything of that nature out of the speaker? or is the receive totally quiet? Double check your CB/PA switch, make sure it's not dirty or something. I'm halfway suspecting a relay issue of some sort, but it is possible that you may have had some stray RF from the linear damage the receive RF amp circuit in some manner. Check for any dirty switches, controls, and connections, let us know how you get on.


~Cheers~

 

[Double R]

well the guy who had it before me unhooked the pa and thats where the extra channels come in , the rf power meter does not move at all only modulation on the base moves

 

[Double R]

if you use anouther radio turn on , and keyed down and lisen throw the 139 it sound like the person whispering , and i have the volume turned up , rf up dynamike up , nothing changes , same sound when ya unplug the radio to

 

[Double R]

will any one tell me how to do moss fet finals in this radio and what will i need to know to do it

 

[Robb]

Putting MOSFET's in takes some circuit mods - they aren't a direct change over/drop in part.

What PLL does this radio have? There is some info on the 858 type PLL conversion to MOSFET's. If not; then better off putting in a stock replacement. If you haven't done this kind of work before - best leave it to a shop that can.

Exitthirteen seems to be able to do the job, might try him to do it.

 

[Double R]

finals are 2 nec's c1096 m267a , ones the driver