TX upgrade for Cobra 29 LTD BT

Discussion in 'CB Radio Forum' started by jimbowilly, Aug 16, 2011.

  1. Aug 16, 2011 #1
    jimbowilly

    jimbowilly Bobtail Member

    37
    6
    Aug 15, 2011
    Troy, NY
    0
    Hi,
    I would like to increase the tx on my Cobra 29 LTD Classic BT.
    Increase swing (modulation) and receive. I'd like to see 25 watts out of this
    radio.
    Does anyone have the mods for this radio?
    Thank you,
    Jimbo
     
    jimbowilly, Aug 16, 2011
    jimbowilly, Aug 16, 2011
    #1
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  3. Aug 16, 2011 #2
    WA4GCH

    WA4GCH Road Train Member

    3,324
    577
    Aug 12, 2009
    Seminole Florida
    0
    EASY FIX ........

    Buy a 100 watt linear with preamp that will fix BOTH problems and not cause any for the radio ...
     
    WA4GCH, Aug 16, 2011
    WA4GCH, Aug 16, 2011
    #2
  4. Aug 16, 2011 #3
    Hanadarko

    Hanadarko Independent Owner/Operator

    2,971
    935
    Oct 1, 2009
    Midwest
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    Natively this radio cannot put out that much power. You need a Linear.
     
    Hanadarko, Aug 16, 2011
    Hanadarko, Aug 16, 2011
    #3
    WA4GCH Thanks this.
  5. Aug 17, 2011 #4
    Rat

    Rat Road Train Member

    1,522
    1,445
    Aug 31, 2008
    Rats nest Grafton North Dakota
    0
    I agree, get a small amp, get the cobra checked out to make sure it will work with the amp in mind, go through your antenna system and make sure everything is up to par for the extra output. A crappy antenna setup will show problems once you hook up a little extra power.

    As far as doing more to the cobra. Well go to Cbtricks.com If you are good with a solding iron and can work on these boards then you should beable to bump it up a little. Just don't expect 25 watts of carrier out of it. Might beable to get it for a short time but it will probly let out the mysterious smoke in a short period of time.

    But I would start with the antenna setup first. A quality antenna will make you heard better and increase your receive as long as everything else is done correctly.

    And yes grounding is the key, ground strapping works the best. It will be hard to get decent body grounding on todays newer trucks with all the fiberglass and plastic body parts. But you want to make sure every peice of metal on the truck is linked together with decent grounding material.
     
    Rat, Aug 17, 2011
    Rat, Aug 17, 2011
    #4
  7. Aug 20, 2011 #5
    jimbowilly

    jimbowilly Bobtail Member

    37
    6
    Aug 15, 2011
    Troy, NY
    0
    I replaced jumper jp36 w/ 16V 220uf cap and installed a 1/4 watt 68 ohm resistor to cap's legs, on the solder side of the pcb.
    This is working great on a 2008 Cobra 29 LTD Classic BT and a 2008 Cobra 29 LTD Chrome.
    This mod lowered the dead key ( carrier ) to 2 watts. Also gave this radio 20 - 23 watts of out put power.
    Tuning the mic gain down to 3/4 position eliminated any distortion in my TX.
    Radios receiving my AM signal 8 miles away reported clear, undistorted reception.

    I also upgraded D1, D2 with higher quality diodes. Which eliminated some of the noise created by poor quality diodes installed at the factory. And increased my receive capability.

    If you are unsure of your soldering abilities ? Take your radio to an shop.
    Cobras are an inexpensive radio, until you burn one out and have to replace it. So if you want a bigger, better cb radio ? Spend the $300.



    Thank you,
    Jimbo
    ​
     
    jimbowilly, Aug 20, 2011
    jimbowilly, Aug 20, 2011
    #5
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