preps
Page 1 of 2 12 LastLast
Results 1 to 10 of 18

Thread: Variable RF power mod for Cobra 142 GTL

  1. #1
    Join Date
    Sep 2016
    Location
    Central KY
    Posts
    161
    Thanks
    16
    Thanked 41 Times in 31 Posts
    Downloads
    16
    Uploads
    0

    Variable RF power mod for Cobra 142 GTL

    I've assembled the "swing kits" with a pot for power level before for the cobra 29's but I want to put one on my 142 for AM. Not SSB. The radio has some sort of swing kit in it but I don't know where to look on the board to find it. I know it has one in it because it dead keys at 1.5 watts and swings to 5 watts. If anyone could help me locate this mod and give me some info on how to put in variable power, that would be very helpful. Thanks guys!!!


    Sent from my iPhone using Tapatalk
    Happy DXing

  2. #2
    Join Date
    Jul 2013
    Location
    Port Orange. FL
    Posts
    1,135
    Thanks
    299
    Thanked 406 Times in 269 Posts
    Downloads
    0
    Uploads
    0
    Well you could have the AM power tuned down and the modulation turned up as well and you could possibly see that kind of power as well Matt. Not saying the radio doesn't have a swing kit as it may very well have one. Check for a cap and resistor close to the final. There will be a cap on the top side and normally a resistor on the solder side of the board near the final. Hope this might help a little. Have a good one. And let me say it now. I am in no way a tech nor do I claim to be. Just throwing some possibilities out there as to what could be. Again, hope it might help. Good day.

  3. #3
    Join Date
    Sep 2016
    Location
    Central KY
    Posts
    161
    Thanks
    16
    Thanked 41 Times in 31 Posts
    Downloads
    16
    Uploads
    0
    i need variable power. it was my mistake, it has no swing kit in it but i want to put variable power in it. i have the kit assembled but i cant figure out where to put it...
    Happy DXing

  4. #4
    Join Date
    Sep 2016
    Location
    Central KY
    Posts
    161
    Thanks
    16
    Thanked 41 Times in 31 Posts
    Downloads
    16
    Uploads
    0
    Does anyone know where I need to install the variable mod at?


    Sent from my iPhone using Tapatalk
    Happy DXing

  5. #5
    Join Date
    Jul 2013
    Location
    Port Orange. FL
    Posts
    1,135
    Thanks
    299
    Thanked 406 Times in 269 Posts
    Downloads
    0
    Uploads
    0
    Back near the final. I believe it's JP36 on the cobra 29. Don't quote me on that though. Google has tons of info on it. Just google cobra 29 variable power mod. Here are a couple of pics and description of how and where it goes.

    The parts you have may not be the same, but the placement should be on the board. Hope this helps.

  6. #6
    Join Date
    Jul 2013
    Location
    Port Orange. FL
    Posts
    1,135
    Thanks
    299
    Thanked 406 Times in 269 Posts
    Downloads
    0
    Uploads
    0
    Sorry this is for a cobra 29. Let me see if I can find one for the 142.

  7. #7
    Join Date
    Jul 2013
    Location
    Port Orange. FL
    Posts
    1,135
    Thanks
    299
    Thanked 406 Times in 269 Posts
    Downloads
    0
    Uploads
    0
    Here is a simple pic of how someone did the variable power mod to 8719 board. Looks as if you cut the trace for VR6 which is the AM power pot. Here is the pic.

  8. #8
    Join Date
    Jul 2013
    Location
    Port Orange. FL
    Posts
    1,135
    Thanks
    299
    Thanked 406 Times in 269 Posts
    Downloads
    0
    Uploads
    0
    I would think you would just add the variable power mod where they are showing that you add a resistor. Add your variable power mod instead of a resistor in its place.

  9. #9
    Join Date
    Jul 2013
    Location
    Port Orange. FL
    Posts
    1,135
    Thanks
    299
    Thanked 406 Times in 269 Posts
    Downloads
    0
    Uploads
    0
    Again, don't quote me on this. Hopefully someone else will answer as well. This was just with a quick google search. If your radio has the 8719 board, then search google for the mod for that board which is a very popular one. Again, sorry to mislead you with the cobra 29 mods and hope you get it all resolved!! Be careful whatever you do and good luck Matt.

  10. #10
    Join Date
    Sep 2016
    Location
    Central KY
    Posts
    161
    Thanks
    16
    Thanked 41 Times in 31 Posts
    Downloads
    16
    Uploads
    0
    Thank you Sean. I wasn't able to locate anything on the 142. I did not search the board though so I greatly appreciate it. I've about got this radio doing some good broadcasting. It's direct injected. I am running about 75 watts going into a ameritron al-80 with the 500z tube in it. It's peaking out at about 1,000 watts. Dead key is about 200 and the swing goes between 900 and 1,050.


    Sent from my iPhone using Tapatalk
    Happy DXing

Visitors found this page by searching for

None

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •