Question about Cobra Mr Hh425li Vp Marine Hand Held Dual Band Transceiver

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My Cobra MR HH425LI don't transmit and received after 5 minutes

I have two Cobra MR HH425LI. After 5 minutes from power up, the radio stop to transmit or received.
On first 5 minutes all MR HH425LI work well (received and transmit ok with the same cobra radio and with other model).
After 5 minutes from power up, the radio stop to transmit or received.!!!:
When I press TX on the screen appared the TX indicator but I don't received anything on all other station on this chanel (on bouth band).
When I press Tx on  other model station (I have many other station) all MR HH425LI don't received the signal (but all other station receiv all ok).
When I press Tx on Cobra MR HH425LI other station don't received the signal.
If I power off the Cobra MR HH425L and Power Up this radio work ok again for only 5 minutes!!!

What can I do to resolvate the problems?
Thank you
Cristian

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5 Suggested Answers

SOURCE: cobra 148gtl

tomcat 1 back ...i have found the fault no modulation on am/usb/lsb.tr -23 a bc458 transister .replaced this transister and wow modulation on all 3 modes thanks zeppfrog for telling me where to look .

Posted on Mar 01, 2007

  • 9 Answers

SOURCE: Cobra 148GTL Missing TX Modulation

The problem is most likely the audio ic . open the radio and see if the diode 44 is blown or see if you see anything that looks like it got hot around the plug area. if not contact me and i will buy it. is it an old or new 148 gtl.Read more

Posted on Dec 06, 2008

  • 14 Answers

SOURCE: Have Cobra 29 LTD CB

Sounds like the PLL circuit....... no channel synthesizer will kill the transmit and receive...... bad crystal or IC could be at fault or if someone has attempted to add more channels could also be cause.

Posted on Dec 22, 2008

Shuttle83
  • 1139 Answers

SOURCE: radio sticks in TX mode after I let go of the button on the mic

Hello williamhicks,

There is a relay in side of the cb that might be sticking. The problem is that this situation might be environmental. You say that you sent it back to Cobra twice for repairs. I think that the place you are sending it to differs enough environmentally so that the problem does not manifest itself. You can test this by exposing the unit to different temperatures, to determine if the internal relay is sensitive to variations in temperatures.

If you do find that the relay has become tempurature sensitive, you can order the part from Cobra, or strangly enough from Radio Shack, since they do carry the same part just by a different part.

I hope this helps,

Thank you,

Shuttle83

http://www.electron-age-technologies-llc.com

Posted on Mar 11, 2009

  • 773 Answers

SOURCE: Cobra 148GTL can't TX on USB

Its the cap that feeds the first transistor to the first of the finals. It is either shorted or burned out.

Or the audio IC. It could be putting just enough out on AM to seem like its working, and then not enough for side band.

look at the caps near the finals. Look for a burn one, or one that could be twisted, or shorted in any way.

Posted on May 05, 2009

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