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What causes the rf MOSFET to go on a cobra 200gtl

My radio cuts out after short speech on ssb I've been told it's the rf MOSFET.why do they blow and can you upgrade to a more resistant mosfet

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  • Contributor
  • 24 Answers

Mosfets are seemingly very unstable the culprit probably is too high of dead key on the radio back it down a little and no there is no upgrade also on that radio if someone is real close to you and keys up it can give you what is called front end overload and it will have no receive and will require a trip to the cb shop to correct this problem also if you use the extra channels in it they are hard to understand just what channel you are actually on .........I had one of these radios and I did NOT like it or the cobra 150 . they seem to be very fragile radios............good luck !!!!!

Posted on Apr 27, 2014

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Posted on Jan 02, 2017

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One Wire
  • 126 Answers

SOURCE: talkback on a cobra 200 gtl dx

This procedure is not as simple as just cutting a wire. Note that you can possibly mess your radio up if any maintenace is not done properly. I do suggest taking your radio to a proffesional to have the talkback removed, but, if you really want to do it yourself, go to ghe following link and basically reverse what has been done.

http://www.cbtricks.com/radios/cobra/150gtl_dx/tsb/cobra_200gtl_dx_tsb_10041.pdf

This is the service bulletin for the addition of talkback to the Cobra 150GTL DX and the Cobra 200GTL DX.

As long as the talkback was added correctly, this can be put back origional.

If this does or does not help, please reply on here or email me at rollincbmods@yahoo.com. I look forward to hearing from you.

Dean
Rollin CBs
Mt. Vernon, TX

Posted on Feb 14, 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

  • 773 Answers

SOURCE: Cobra 200GTL: Clarifier affects TX

Unfortunately, most people look to unlock the clarifier in radio's it is locked in.

From what I understand it is possible to lock it in that radio, however I do not know it because I usually unlock it in my radio's.

I also did a search, and asked a few people I know who are also very good with radio's and they do not know either. The only thing I found was this, and you have to pay this shop to do it.

http://cobraworxshopz.com/12.html


Posted on Oct 03, 2009

SD Tech
  • 14553 Answers

SOURCE: I just purchased a cobra 29 LTD Classic mobile CB radio.Pro tuned high performance Mosfet Final I have a palomar 450 LD mosfet linear.will i have any problems?

Not if the power output from radio to amp is set correct and the jumper for coax is correct length and there is absolute perfect match between them and the antenna used. Afterthought: also the amp better be connected to something big enough to power it.

Posted on Apr 29, 2012

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1 Answer

What causes the rf MOSFET to blow on cobra 200?


They blow for all kinds of reason. Just replace them an check resistors around them. Caps should be checked as well. Just replacing mosfet is not usually enough. They have a way of taking other components out to.

Mar 23, 2014 | Cobra Radio Communications

1 Answer

My cobra 200gtl rev 2 cuts out on ssb after a few minutes


It sounds like the final transistor may be shorted/burned out. If you don't know how to locate or test the transistor you'll have to take it in to a tech. These transistors are usually quite cheap but as to the labour cost it depends on your tech. Usually what causes this damage is a bad antennae match or a bad antennae itself, even a shorted antennae cable. After you've repaired the radio check the antennae and cable first before connecting it up again, then check your match with an SWR meter. Good luck

Mar 23, 2014 | Cobra 200 GTL DX 4-Channels Base CB Radio

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My cobra 200gtl has no transmit


hi More than likely your pa transistor has blown have you checked it with a power meter if so r you getting the red tx led when the ptt is pressed if so then your problem lies with the rf transistor
replacing rf transistor

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Cobra 2000 with a d 104 mic and a palomor tx100 bi linear amp...how can if possible make the amp key up with less than one watt on the ssb side..Radio has a 4 watt dead key on am and i have ajusted the...


Hi, my name is John. Adjust the radio to key 1 watt, then switch to SSB on radio,then switch to SSB on amp, key down and adjust to 1 watt on amp. enjoy !!!!!! ...hope this was very helpful....

Aug 31, 2010 | Cobra 148 GTL 120-Channels Base CB Radio

1 Answer

Cobra 200GTL: Clarifier affects TX


Unfortunately, most people look to unlock the clarifier in radio's it is locked in.

From what I understand it is possible to lock it in that radio, however I do not know it because I usually unlock it in my radio's.

I also did a search, and asked a few people I know who are also very good with radio's and they do not know either. The only thing I found was this, and you have to pay this shop to do it.

http://cobraworxshopz.com/12.html


Feb 02, 2009 | Cobra 200 GTL DX 4-Channels Base CB Radio

1 Answer

Cobra 148 gtl b no recieve


make sure that the rf gain is turned up all the way.Check diodes D-12&D-13.

Jan 08, 2009 | Cobra 148 GTL 120-Channels Base CB Radio

1 Answer

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.

Jun 23, 2008 | Cobra 200 GTL DX 4-Channels Base CB Radio

2 Answers

Talkback on a cobra 200 gtl dx


This procedure is not as simple as just cutting a wire. Note that you can possibly mess your radio up if any maintenace is not done properly. I do suggest taking your radio to a proffesional to have the talkback removed, but, if you really want to do it yourself, go to ghe following link and basically reverse what has been done.

http://www.cbtricks.com/radios/cobra/150gtl_dx/tsb/cobra_200gtl_dx_tsb_10041.pdf

This is the service bulletin for the addition of talkback to the Cobra 150GTL DX and the Cobra 200GTL DX.

As long as the talkback was added correctly, this can be put back origional.

If this does or does not help, please reply on here or email me at rollincbmods@yahoo.com. I look forward to hearing from you.

Dean
Rollin CBs
Mt. Vernon, TX

Feb 13, 2008 | Cobra 200 GTL DX 4-Channels Base CB Radio

1 Answer

148NW ST No TX AM or SSB


finals need to be replaced, as they are fried,, hence no output,,and if you are lucky you haven't fried the pre-amp as yet....as the pre amp is REAL EXPENSIVE....so stop keying it up

Jul 27, 2007 | Cobra 148 GTL 120-Channels Base CB Radio

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