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Cobra 25 lx rf power output fail - Cobra Radio Communications

Posted by Anonymous on

  • Mike Charette Mar 01, 2015

    Hi Anonymous, I want to help you with your question, but I need more information from you. Can you please add details in the comment box?

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  • Expert
  • 63 Answers

Need more info

Posted on Mar 05, 2015

6 Suggested Answers

6ya6ya
  • 2 Answers

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Posted on Jan 02, 2017

SOURCE: Cobra 25 LTD

most cbs have the same power cod

Posted on Aug 14, 2008

Benimur
  • 6966 Answers

SOURCE: new power chip

Hi,

To my knowledge on a Cobra 29 board, replacing TR14 (2SC2029) with a 2SC1969 is supposed to improve/increase the TX power output. Additionally however, L12, 13 & 14 must also be adjusted while the 29 is hooked up to a dummy load/watt meter. Should you wish to try for experimental purposes only:

  • Modulation improvement - adjust VR4 to desired level or cut D11or max talkpower remove TR18 .
  • replace TR14 with 2SC1307 (or 2SC1969).
Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.

Good luck and kind regards. Thank you for using FixYa.

Posted on Sep 06, 2008

SOURCE: Older Cobra 25 ltd

did the gauge stop working or the radio. the gauges on older radios fail quite often . you can order replacements

Posted on Sep 15, 2008

Communicomm
  • 90 Answers

SOURCE: Cobra 200gtl High Power Transmit problem??

Depending on the type of power supply, radio frequency (RF) energy from the transmitter may be 'fooling" it into thinking that you're overloading it. Check to see if there's any discernible dimming of the meter lamp when this problem occurs, if so, the supply is the culprit.

Otherwise, its probable that the final amplifier transistors are overheating, either they are 'leaky' or not properly attached to the heat sink.

Posted on Sep 26, 2008

Bat1956
  • 585 Answers

SOURCE: af audio power amp

Just because the chip is warm doesn't mean it's bad, especially if it seems to work fine otherwise. Do however make sure that the device is properly heatsinked, and inspect the work done in the process of any modifications. If for some reason the device is self-oscillating it could do so at a frequency above hearing thereby going unnoticed. That will cause the device to overheat, and also make modulation weak and the RF to splatter out of band. You'll have lots of power on the RF wattmeter, but people can barely hear you if that's the case.

Posted on Jul 11, 2009

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Af audio power amp


Just because the chip is warm doesn't mean it's bad, especially if it seems to work fine otherwise. Do however make sure that the device is properly heatsinked, and inspect the work done in the process of any modifications. If for some reason the device is self-oscillating it could do so at a frequency above hearing thereby going unnoticed. That will cause the device to overheat, and also make modulation weak and the RF to splatter out of band. You'll have lots of power on the RF wattmeter, but people can barely hear you if that's the case.

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2 Answers

Older Cobra 25 ltd


did the gauge stop working or the radio. the gauges on older radios fail quite often . you can order replacements

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