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Knight C-577 Compressor- anyone ever seen one?

Discussion in 'Ham Equipment' started by Bow, Jun 9, 2019.

  1. Bow

    Bow Bastard Modulation Engineering

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    I picked Knight C-577 Compressor up at a local hamfest a while back... she is an oldie for sure...

    I got some time to throw it on the bench today... signal generator input, monitored the O'scope on the output... it works.... and doesn't take much at all to drive it



    The meter needle has broke off the movement, and it uses 1/4" TRS for input and output.

    However, I would like to find a schematic on it...

    Anyone have any leads? My Google-Fu has come up dry
     

    Attached Files:

    Shadetree Mechanic likes this.

  2. Bow

    Bow Bastard Modulation Engineering

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    Here it is in action...

    1KHz @ 30mv drive
    9vdc power

    Bypassed signal
    IMG_20190609_143913560.jpg
    Lowest Compression setting
    IMG_20190609_143944491.jpg
    Highest Compression setting
    IMG_20190609_144057241.jpg
     
  3. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    Looks like it is overdriven on high?
     
  4. mrgumby

    mrgumby W9WDX Amateur Radio Club Member

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    52999653-851A-4E08-AE86-D72353384759.png
     
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  5. Bow

    Bow Bastard Modulation Engineering

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    Not overdriven.. it is a clipping circuit
     
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  6. Bow

    Bow Bastard Modulation Engineering

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    Thank you sir! Where did you find that?
     
  7. mrgumby

    mrgumby W9WDX Amateur Radio Club Member

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    Bow likes this.
  8. mrgumby

    mrgumby W9WDX Amateur Radio Club Member

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    Page 61
     
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  9. nomadradio

    nomadradio Analog Retentive

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    I'd venture to say that the sideways S-meter from a derelict mobile CB is probably a decent match for the broken meter.

    Replacing all the electrolytic caps in there would probably clean up the waveform at a high drive level.

    73
     
  10. Bow

    Bow Bastard Modulation Engineering

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    Swapped the only electrolytic (C2 in the schematic) it was a 50uf/10V, I had a 68uf/10V close enough

    Looks like the gain dropped a tad, looks like it cleaned up the signal a bit.
     
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  11. nomadradio

    nomadradio Analog Retentive

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    I'd replace all five, but if you saw a difference changing just one, that's a hint.

    73
     
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  12. Bow

    Bow Bastard Modulation Engineering

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    Yup, I agree, they are all pretty common...
    the others are
    3 are 0.1uf
    1 is 0.0033uf
     
  13. nomadradio

    nomadradio Analog Retentive

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    Hmm. Counted five caps with that "+" symbol alongside them in the schemo. But no capacitance values visible.

    If they are aluminum electrolytics, age is your enemy.

    73
     
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