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Cobra 18 WX ST II (don’t laugh)

Discussion in 'CB Radio Modifications' started by ForestRunner98, Feb 11, 2020.

  1. ForestRunner98

    ForestRunner98 Well-Known Member

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    Hello everybody!

    I am new to the CB world. I originally got my radio just for off roading BUT I kinda got the bug for CB. Also the radio was DIN sized.

    Does anybody know how to lower deadkey wattage on this radio? Reason is I wanted to add a RM Italy Kl203. I believe the radio is already under powered by the factory but I didn’t want to kill the amp with high input watts.



    I appreciate all your responses!! Thank you!!

    Bill
     

  2. 711

    711 Well-Known Member

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    If you know of a good shop to do your radio, you could do the adjustable deadkey mod like the cobra 29 JP36 variable dead key mod. I don’t have an 18 in front of me so if there ain’t a Jumper available, they need to cut a trace and install the mod there

    72654DBD-CC30-4797-B7F8-444FD5838404.jpeg
     
  3. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    This the best answer I can give you. Read through the alignment procedure adjust the power level for no more than 1.5 watts. If you do not have an oscilloscope adjust nothing. Be sure that you are using a resistive load of 50 Ohms.
    http://cbradio.nl/cobra/Service_Manual_Cobra_18WX_STII_EMG.pdf

    2. TX Carrier output power 1. Channel set normal band CH 19. 2. Set TX mode. 3. Connect an RF wattmeter to the antenna socket. 1. AdjustL21,L20 andL17 for 1.5 max. watts RF output power. 2. Check TX CH1 and CH40
     
    #3 Tallman, Feb 11, 2020
    Last edited: Feb 11, 2020
  4. ForestRunner98

    ForestRunner98 Well-Known Member

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    Ok...these are great instructions!! I don’t have a O-scope but I do have a watt meter. I can turn L17, L20 and L21 and check the watt meter as I key down and see if I am at 1.5 watts.

    I may be over my head but I am willing to try. I am not to comfortable in adding jumpers or resisters though.
     
    Tallman and Redbeard U812 like this.
  5. Redbeard U812

    Redbeard U812 WDX-1030 / U812 South Texas

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    It's a relatively low cost radio. Might just be the most inexpensive way. If you mess it up not much lost.

    Can always pick up the 980 for 100+ as a replacement.

    Keep up the trial and error, this pairing the 18 with a small amp is interesting.

    Run Forest.....run (y)

    ......and welcome.
     
  6. ForestRunner98

    ForestRunner98 Well-Known Member

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    You’re right! Since the radio is low cost it would not bother me if it gets killed in the process. I just don’t want to kill the radio AND amp.LOL

    I was looking at the Bearcat 980!! I believe it’s DIN sized and price is good for a nice radio.

    It would be kinda cool to pair the Cobra 18 with the little amp. Just to get a little further out. Not looking for crazy wattage. So let’s see how this pans out.

    BTW...would I be able to use the 980 and amp by turning the RF power down via knob/button to get a low DK??
     
    #6 ForestRunner98, Feb 12, 2020
    Last edited: Feb 12, 2020
  7. Redbeard U812

    Redbeard U812 WDX-1030 / U812 South Texas

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    I've been running my 980 out of the box with a Palomar 450LD, only problem I've got is the stupid switch in my D104M6B failing. Won't key sometimes, couple presses and it works. Thought maybe I was taxing the finals in the 980, swapped back to stock mic and everything was fine.

    Ran my 30 year old Uniden PC66 for years with the same Palomar 450LD with a 4w dead key.

    I'm sure that Italian foot warmer will be just fine with the 18 as is. Slowmover runs his out of the box 980 with that same amp you have.
     
    Slowmover and Eldorado828 like this.
  8. Redbeard U812

    Redbeard U812 WDX-1030 / U812 South Texas

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    Tore an old pot out of a dead radio, added a resistor to create a variable on one of mine years ago. It worked, but I didn't need to do it.
     
    Shadetree Mechanic likes this.
  9. Riverman

    Riverman Member of Sorts

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    My ears just perked up!
    Everybody and their dog says the KL amps can only handle 1.5 watts or they blow up. Am guessing an out-of-the-box 980 does 3.5.

    Slowmover, what’s the story with your setup? It could mean a boatload of new 980 and KL203 buyers. Me included. :D
     
    Slowmover and Eldorado828 like this.
  10. Redbeard U812

    Redbeard U812 WDX-1030 / U812 South Texas

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    My 980 does a little over 4w dk on my new swr/pwr meter. (y)
     
    Slowmover likes this.
  11. Riverman

    Riverman Member of Sorts

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    4.0? Yikes! :eek:
    Apparently your amp is geared for that, but a KL 203? (n)
    Maybe I’ve been hearing wrong all this time. o_O
    Hope so! :p
     
    Slowmover likes this.
  12. Redbeard U812

    Redbeard U812 WDX-1030 / U812 South Texas

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    I PM'd slow about this thread. So maybe he can shed clear light on what he's got.
     
    Slowmover and Riverman like this.
  13. Redbeard U812

    Redbeard U812 WDX-1030 / U812 South Texas

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    If I didn't have two amps already I would be looking closer at those Italian jobs.
     
  14. Riverman

    Riverman Member of Sorts

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  15. ForestRunner98

    ForestRunner98 Well-Known Member

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    Holy mackerel......I thought nobody would care about this thread but woah!!!! LOL
     
    Riverman and Shadetree Mechanic like this.

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