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Cobra 29 ltd chrome with mosfet super tune

Discussion in 'CB Radio Modifications' started by 805 california, Jul 28, 2016.

  1. 805 california

    805 california Active Member

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    So I did the mosfet install on a 29 ltd chrome and followed the directions on cbtricks and I am only showing 12 watts pep. I thought I would see atleast 20 watts pep. Do you only see the big numbers with the 29 ltd classics??


     

  2. sonoma

    sonoma Sr. Member

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    what is the voltages going into the gates of the fet. should be about 3.5 volts. are you sure the mosfet you installed is up to snuff. I bought some a couple years ago that were not very good and only got about 6 watts out of them . had to throw them away. also did you peak the stages going to the mosfet after the new install. that is a must do issue also.
     
    222DBFL and Robb like this.
  3. 805 california

    805 california Active Member

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    Which fet are you referring to? The mosfet kit I got was off ebay. Which stages are you referring to? I peaked the two coils and l17 and l20 as per instructions which didn't seem to do a whole lot. Thanks
     
  4. sonoma

    sonoma Sr. Member

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    here is the procedure I use for a tune on the cobra 29. it shows all the cans to tune for tx. no need for me to just write them down. not sure what they sold you for the kit. never bought one off ebay. make sure you have the proper voltage at the gate. if the voltage is low the output will be low.

    http://downloads.cobra.com/CB/Models/29-SERIES/29LTDalign.pdf
     
    #4 sonoma, Jul 28, 2016
    Last edited: Jul 28, 2016
  5. 805 california

    805 california Active Member

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    Thanks for reply I will check for 3.2 volts. The ebay kit came with the 520 mosfet and all the caps, resistors and diode. Thanks
     
  6. w9cll

    w9cll W9WDX Amateur Radio Club Member

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    You know you are not going to see any noticeable difference in your signal between 6 and 20 watts? Not really worth the cost and effort.
     
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  7. 805 california

    805 california Active Member

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    Yeah well it was my understanding that people see at least 20 watts pep with the mod. I'm just wondering what the deal is...
     
  8. sonoma

    sonoma Sr. Member

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    I do not change out a stock final unless it is blown myself. the stock final works just fine as far as I am concerned. I would just as soon have the 2078 final over a mosfet any day. people see a radio claiming 40 watts with the mosfet and the only person that knows it is doing more is the guy transmitting. the receive is the same until you get up to 100 watts.
     
  9. w9cll

    w9cll W9WDX Amateur Radio Club Member

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    There is no noticeable change in signal from 10 to 100 watts, 100 watts to 500 there is a change. Over 500 there is less of a change.
     
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  10. w9cll

    w9cll W9WDX Amateur Radio Club Member

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    If you are doing this a learning process then have at it. If you are doing it thinking your signal will get better then you will be disappointed.
     
  11. sonoma

    sonoma Sr. Member

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    I just hate seeing a guy pay 20.00 for 2.00 worth of parts thinking the radio will be a screamer after putting the part in the radio. those ebay sellers are just there to make all the money they can. just like the rf limited trb X3 echo boards are selling on ebay now for 75.00 plus since you can not find them any where. they got a few and marking them up way more than what they sold for in the past. just like the sra-198 mics were selling for 20.00 shipped then got hard to find foer a while and the guys were putting 50.00 plus on a used one trying to squeeze every penny out of some one that wanted one.
     
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  12. 543_Dallas

    543_Dallas Sr. Member

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    The math doesn't add up. 10 times the power doesn't make a difference until you get to 100 watts, then only 5 times will make a difference?

    How does the signal meter on the receiving end know how many whiskeys you're running?

    Then let's put that radio in front of a good old CB lenyar. Now difference in 6 to 20 might make more of an impact. Even more if we were talking real power and not hack job watts.
     
  13. w9cll

    w9cll W9WDX Amateur Radio Club Member

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    Math smath going from 5 to 20 is not going to show.
     
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  14. LeapFrog

    LeapFrog Wielding Hanlon's Razor

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    I hear the older radios (before they where made in China) make more power with the conversion. I have to agree with the other members in this thread, nobody will notice your signal increase, because you won't be "getting out" any better with 25 pep watts over 12 pep watts
    (Correction: a slight increase may be seen but hardly noticed on the receiving end) Not worth it i.m.o.

    Did you construct or buy the "companion part" this is necessary for the mosfet conversion to work properly...

    Also read this taken from the alignment procedure for your radio.
    If you do not have this tool please do not make anymore adjustments inside the radio.
    I am just trying to save you from headaches and grief down the road..

    But please do continue to read & learn. Over-modulation and splatter can come about with an ebay swing kit, read up on why that's bad. The mosfet conversion can produce a clean signal & perform well, it requires additional work besides just following the cbtricks pdf though.
    (Also buying a capacitor assortment, and resistor kit will give you more than enough bits to play with and build your own swing kit for much cheaper, these ebayers do this and make a killing on mark-up)

    -Sam
     
    #14 LeapFrog, Jul 29, 2016
    Last edited: Jul 29, 2016
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  15. 222DBFL

    222DBFL Sr. Member

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    I'm about sure if he bought the parts off eBay he doesn't have an oscilloscope. Just a guess.
    And like others have said, why ruin a perfectly good radio? That is unless you are trying to get your learn on. And this does require some specialized tools to perform correctly.
    Another one sucked in by the SNAKE OIL BS being sold on eBay. 2.00 in parts, probably cost 10 times that to buy. Hopefully lesson learned. If not, good luck. I'll leave it at that as I am no radio tech, but at least know the truth about most of the BS stuff people peddle on eBay as some special kit that will make your radio much better than it is. It's just BS!! JMHO.
     
    LeapFrog likes this.

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