Intermittent TX. Audio section is fine, just no power output sometimes. LED goes red, RX goes away, radio meter shows no output along with external power meter. I've been told transistors(final,driver) are either good or bad, is this true? Good, strong TX when it works.
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148
- Thread starter Kwijibo
- Start date
have you tried another mic on the radio ? as in the mic plug maybe being screwed up or wires coming off ? ....Cold solder joint on the board ? ....It works and then it don't work ....whatever it is ? it doesn't sound to very serious .
Sounds like L-Bones is right )-: it could be a number of things going on ,Voltage Regulator,finals,driver , it really sounds like it has gone from having problems to getting worse since you started the post )-: .....trying a different mic was the easy way out sometimes for others ,but unfortunately it's just not always the case.Let us know what the problems were if and when you take it to the radio doctor. good luck to you and sorry I couldn't be of much help to you here. SK
Had same problem
I had the same problem with a 148 NW ST. I after weeks of pulling hair out of my head I found the problem.
Near the rear of the radio on the Coax connection side, there is a 3 pin transistor that somes from the side and solders to the solder side of the board. Look with a magnifying glass and make sure all 3 leads are making good contact and none of them have a cold solder joint.
I reflowed the solder on all 3 and my problem has disappeared 100%.
Good luck
I had the same problem with a 148 NW ST. I after weeks of pulling hair out of my head I found the problem.
Near the rear of the radio on the Coax connection side, there is a 3 pin transistor that somes from the side and solders to the solder side of the board. Look with a magnifying glass and make sure all 3 leads are making good contact and none of them have a cold solder joint.
I reflowed the solder on all 3 and my problem has disappeared 100%.
Good luck
You didn't check any of these three radios on SSB transmit, did you?
If the AM ONLY is bad, but SSB still transmits okay, that's a pretty straightforward and common failure.
If there is no SSB transmit either, then it's not just the AM modulator transistor, but something else.
The 148GTL isn't really one radio, it's an entire extended family of them. It's been in production so long, the list of factories who built them for Cobra is as long as your arm, almost.
Where it was made, and when (if it says) can be a large troubleshooting clue, in some cases. Narrows down which particular radio out of a dozen it really is, at least.
73
If the AM ONLY is bad, but SSB still transmits okay, that's a pretty straightforward and common failure.
If there is no SSB transmit either, then it's not just the AM modulator transistor, but something else.
The 148GTL isn't really one radio, it's an entire extended family of them. It's been in production so long, the list of factories who built them for Cobra is as long as your arm, almost.
Where it was made, and when (if it says) can be a large troubleshooting clue, in some cases. Narrows down which particular radio out of a dozen it really is, at least.
73
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@ Geoexplorer69:Coax question. I just put up a new Sirio monsoon base antenna with 100’ of rg8u coax testing with myMFJ antenna analyzer shows 1.4 swr at 26.965mhz and a 1.1 at 27.405 mhz . When I checked the ohms it’s steady a 30 ohms across the entire bandwidth.
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