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only on lower dead key

Discussion in 'General CB Services Discussion' started by 1iwilly, Sep 28, 2020.

  1. 1iwilly

    1iwilly Well-Known Member

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    so today while checking to see is my 148 gtl&2000 gtl are still on frequency i notice that when i lower the dead key anything less than 2 watts the frequency starts going all over the place bring it back to 2 watts and she back on the frequency i've seen this before but don't remember the fix ???


     

  2. FredTx63

    FredTx63 Well-Known Member

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    How are you checking the TX frequency? External counter/meter or internal?
     
  3. AudioShockwav

    AudioShockwav Extraterrestrial Admin
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    Turn the Mic gain all the way down when checking on AM

    73
    Jeff
     
    357magnum likes this.
  4. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    You cannot check frequency on SSB unless you are using the dual tone method.
    Also you need to have a certain amount of power to be able to sample it. Some where there is a resistor network used to attenuate the in put of the counter.
     
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  5. 1iwilly

    1iwilly Well-Known Member

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    this is on am only and yes mike gain is off


     
  6. 1iwilly

    1iwilly Well-Known Member

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    brand new 6 digit counter with so239

     
  7. Shockwave

    Shockwave Sr. Member

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    Hello Jose, What you are seeing is somewhat normal. The coupling cap feeding the counter across its two SO-239 connectors is a low enough value that the counter is not able to receive enough input to lock, with a reduced carrier. The radio is not changing frequencies, the counter is just unable to detect an input below a certain level. Doubling the value of whatever coupling cap they are using, will half the drive power required to lock the counter.

    PS: If you increase the value of this cap, do not install the counter after an amplifier. You may over drive and burn out its input transistor from too much drive now.
     
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  8. 1iwilly

    1iwilly Well-Known Member

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    thanks, shockwave yes I only use the counter to set frequency nothing else
    now that i know that is the norm i'll let be by the way. thanks for the replies shock i'll see you soon i got call back to work for oct 5th got my antenna and radio for my oil truck all ready to go

     
    Shockwave likes this.
  9. 543_Dallas

    543_Dallas Sr. Member

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    I've always used a single tone. A two tone test would not work. If you're talking about something different please give more details.
     
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  10. bob85

    bob85 Supporting Member

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    single tone for ssb frequency & subtract the audio tone frequency from the counter reading to get your suppressed carrier frequency.

    Two tone for ssb linearity testing,

    Shockwave nailed it,
    the counter is undersampling at low deadkey due to the loose coupling needed to handle higher power on a counter with narrow dynamic range.
     
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  11. nomadradio

    nomadradio Analog Retentive

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    All counters will have a minimum input level that maintains a steady count. When the level falls to this threshold you get random numbers.

    Modulating the carrier also does this.

    A steady single tone into a SSB transmitter yields a RF carrier that a counter can read and show a stable count.

    And a carrier is pretty much the only kind of RF a counter can handle and show a steady reading.

    73
     
    144inBama and tecnicoloco like this.

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