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Galaxy 959 b, (unlocked) clarifier off kilter

Discussion in 'CB Radio Modifications' started by Uncle Ronnie 336, Jul 12, 2021.

  1. Uncle Ronnie 336

    Uncle Ronnie 336 Active Member

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    Friend bought this radio. Clarifier is all the way to the right and it's a hair short of on freq. Seems that the tx/Rx are both in sync. Not sure why it's doing this


     

  2. Ranch55

    Ranch55 Sr. Member

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    It most likely was not aligned properly after the clarifier was "unlocked" to sync the transmit and receive tuning together.
    Need a very good frequency counter to do that.
     
    Crawdad likes this.
  3. groundwire

    groundwire Sr. Member

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    Whenever you do an unlock clarifer mod on a cb radio you have to do a frequency alignment on it. They are usually always off if you dont.
     
    Ranch55 likes this.
  4. Uncle Ronnie 336

    Uncle Ronnie 336 Active Member

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    Right now it's just low of center slot with declarifier all the way over to the right. The transmitter and receiver do move together
     
  5. Ranch55

    Ranch55 Sr. Member

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    Doesn't make any difference at all where the knob is located.
    The internal stops on the potienometer determine the adjustment position.
    The alignment needs to be performed with the clarifier pot in the centered position.
     
    tecnicoloco likes this.
  6. nomadradio

    nomadradio Analog Retentive

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    The 959 has three trimmer coils for the clarifier center slot adjustment. One for each mode AM, USB and LSB.

    What you can do about it kinda depends on what you have in the way of tools to work with.

    Biggest bummer is you can't use the radio's counter for this. It has to be unplugged to expose the tuning slugs for this adjustment.

    73
     
    tecnicoloco likes this.
  7. Uncle Ronnie 336

    Uncle Ronnie 336 Active Member

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    on that note if I unplugged the counter and made my adjustments would the counter automatically be correct or would I have to recalibrate that too?
     
  8. nomadradio

    nomadradio Analog Retentive

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    The counter/display module has a tiny surface-mount trimmer cap near the timebase crystal. But it will affect the reading of all modes pretty much equally.

    The three trimmer coils are each switched into the crystal circuit one at a time to "pull" the PLL master crystal up or down as needed to compensate for the internal carrier frequency. The carrier crystal's frequency moves to the top of the SSB filter's passband for LSB and to the bottom of the filter's 'frequency window' for USB. AM mode puts the carrier dead in the middle.

    When the carrier crystal's frequency "zigs" up or down changing modes these trimmer coils "zag" the radio's PLL the opposite amount to keep the radio's center frequency the same for all 3 modes.

    Just need a way to watch the PLL's frequency with the radio's counter unplugged.

    We use a signal generator with good frequency calibration. The trimmer coils for sideband get set for zero beat on USB and LSB. This is done by modulating the signal generator with a 1 kHz tone, and using a 1 kHz tone generator with a speaker on it. There will be an audible beat note between the tone pitch coming out of the radio speaker and the tone box speaker. When the two pitches are identical, the radio is within a couple of Hertz of the same frequency.

    Not the technique suggested in the alignment instructions, but a more-precise method than waiting a full second for a counter to update its readings.

    73
     
  9. Dr_DX

    Dr_DX Well-Known Member

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    Or a different way to fix the problem that will probably give you a more stable voltage source for your Clarifier.

    Problem:

    The radio is tuned, but when the constant voltage was applied to the clarifier, it was too low. Hence why the clarifier is full clockwise (max voltage) to try to get "on" freq.

    The fix:

    Make a constant voltage source using a L7809 and a precision multiturn 10K trimmer potentiometer. Bolt the L7809 to a heatsink (side of radio, use grease), run the 9 volt output to the trimmer and the output of that goes to the high side of the clarifier. Center the Clarifier knob, then just zero beat a radio known to be on frequency (on SSB) by adjusting the brass screw on the trimmer. As long as no one has messed with the trimmer coils for AM, LSB, and USB, you will be on freq. on the other modes too.

    Or, if you don't have a radio to zero beat, just listen in SSB mode to a station that is "on freq." and tune them in by adjusting the trimmer.

    You don't have to have any test equipment or non metallic tools to adjust the coils, etc.

    Just my .02
     
    tecnicoloco and TheRealPorkchop like this.
  10. TheRealPorkchop

    TheRealPorkchop Certified Sith Pimp

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    Almost every radio I personally own has a regulated source in it like that, it's become my trademark I think.

    You wanna really pull your hair out with one of those radios? Put a viagra blue board in it... or a 2547, same radio. It'll drive you batty trying to get SSB to line up right and act right. I finally gave up and removed them, I don't do that mod anymore unless it's only gonna be used on AM.
     
    Slowmover likes this.
  11. Uncle Ronnie 336

    Uncle Ronnie 336 Active Member

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    I got it centered. Running nice
     
    Handy Andy and tecnicoloco like this.
  12. nomadradio

    nomadradio Analog Retentive

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    Hmmm.Thought it was 78 L 09.

    Odds are more hits will turn up searching for that one.

    73
     
  13. NZ8N

    NZ8N Well-Known Member

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    Or LM7809.which is a 1 Amp TO220 package (like a final). I prefer LM78L09 which is in a 100mA TO92 package, like a small signal or switching transistor. 1 Amp is overkill for just this one circuit, the smaller 100 mA regulator will handle the Clarifier circuit just fine.
     
    Slowmover and Handy Andy like this.

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