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KL203P linear

Discussion in 'Amplifiers' started by Robert Cook Sr, Feb 21, 2021.

?

need to know do I send unit back to seller of and adjustment I can make to linear??

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  1. Robert Cook Sr

    Robert Cook Sr New Member

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    I just checked system again using Peak on my pdc600 meter. I'm getting around 50 on dead key and around 85 watts on modulation, and SWR seems to back up a little while talking on it. Without leaner SWR is 1.1 and box jumps up to about 1.2.5 and then falls back a little while talking. I noticed box getting a little warm while talking to contact for first time using it. I keep under edge of driver's seat. I've read on forums that average is better than Peak power but meters seem to swing correctly on peak better than average. Should I have any worry about leaner working ok or not. My contact about 5-6 miles away on mobile said it sounded fine good & loud using power mike. Thanks for all help & suggestions here, I learn every day. by the way the voltage is 12.3 engine off and average v13.8 when engine running at idle, Nissan will go up to 14.5 volts if battery needs it and then drop back to 13.8 driving also I checked radio output engine running is 4 watts modulation These test were done using truck 102"whip not dummy load


     
    #16 Robert Cook Sr, Feb 22, 2021
    Last edited: Feb 22, 2021
    144inBama likes this.

  2. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    Output power
    100 W MAX

    For those of you who aren’t familiar with this amplifier, it’s a small amplifier (sub-compact would be the way to describe it) capable of around 100 watts on AM and 140-160 watts on SSB.

    RM KL-203P MOSFET Linear Amplifier.


      • DRIVE POWER: 0.5W – 10W (PEP MAX) while talking using AM.
      • 1 – 20W SSB input
      • Up to 100W AM/FM 200W SSB output
      • 13.8V DC
      • Switchable SSB Delay Relay
    RM Italy KL203P CB Amplifier | CB Radio Magazine
     
    Slowmover likes this.
  3. ForestRunner98

    ForestRunner98 917 SoCal

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    @Mr Cook Sr...Maybe try to lower the radio’s DK even lower. 1w and see if that improves it. On the U980 you have to go into the inside of the radio so it’s not as easy as other radios. But if you have time, it’s worth a shot. You’re at 50w DK now so your definitely getting closer to the ideal ratio.
     
  4. Robert Cook Sr

    Robert Cook Sr New Member

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    Thanks for info. I'm not too familiar with insides of these new radios. I can't look at board and know what each section does. Plus in 1973 when I went to school and haven't used my brains much in 50 years working with CB radios and they have gone from coil output to other means, maybe some helpful instructions would be nice, I have copy of specs for 203P here in front of me. Thanks for help
     
    #19 Robert Cook Sr, Feb 22, 2021
    Last edited: Feb 22, 2021
  5. 144inBama

    144inBama Sr. Member

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    Just got finished checking mine out....
    Results:
    SWR: 1:1.2
    Cobra 29LTD Chrome @ 12 watts PEP
    Engine off, battery @ 12.7 VDC = 100 watts PEP
    Engine running battery @ 14.8 VDC = 150 watts PEP
    Your numbers vs volts seem to be inline with my results.
     
    ForestRunner98 and Slowmover like this.
  6. Bow

    Bow Bastard Modulation Engineering

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    If you check out my thread in the Export CB section, I have a lengthy discussion about this amp..

    1.75w carrier drive is about the max you can push it with 100% modulation before you start clipping the peaks

    Set the radio drive up so you have a Carrier of ~25w out of the amp, and leave it... that will gave you, when modulated, around 100-110W PEP

    You won't gain anything on the RX end by pushing it harder, and might even keep you in the channel you are transmitting on...
     
    #21 Bow, Feb 22, 2021
    Last edited: Feb 23, 2021
  7. ForestRunner98

    ForestRunner98 917 SoCal

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    Any updates OP???
     

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