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OVER 130% MODULATION!!!

Discussion in 'General CB Services Discussion' started by space cowboy, Jan 1, 2014.

  1. space cowboy

    space cowboy Quack Quack

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    MIDLAND 78-999


     

  2. AudioShockwav

    AudioShockwav Extraterrestrial Admin
    Staff Member

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    They were very nice radios, I wish I had never got rid of the one I had.




    73
    Jeff
     
  3. Mudfoot

    Mudfoot Sr. Member

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    I asked the guy the other day about the sideband issue... Says it has no receive or transmit on either USB or LSB, dead air, no sound at all.
     
  4. ExitThirteen

    ExitThirteen Grumpy and Cranky

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    This is Midland's version of the GE Superbase. Exact same board in both radios, the "double-sided" PLL02A SSB chassis. Stay away from these like the plague unless you're just going to buy the radio for AM use only, or to put on the shelf as a collector's item. I've had several of these and the GE Superbase models come across my bench, all with the same issue, SSB problems. Some had no TX/RX, like this one, other has problems with SSB "bouncing frequency" under modulation. They look neat, but unfortunately, their performance is less than spectacular. :(

    ~Cheers~
     
    5 people like this.
  5. unit_399

    unit_399 EL CAPO

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    Most of the problems with these sets center around the connectors between the 2 boards. Assembly/disassembly stresses the connecting pins (and there are so many of the damn things) causing solder fractures everywhere. Now that these sets are 30+ years old, the connectors themselves are becoming a problem.

    - 399
     
  6. lolpetewtf

    lolpetewtf Member

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    I only buy if they do 150% modulation at least. 130 is for noobs.
     
    1 person likes this.
  7. lolpetewtf

    lolpetewtf Member

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    ...In the hobby for two years, sort of new here. I am kidding in the above post ;)

    lol! :laugh:
     
  8. space cowboy

    space cowboy Quack Quack

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    I hear you, I can't understand you because you're overmod, but I hear you.
     
    2 people like this.
  9. GnG8d

    GnG8d Well-Known Member

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    130-150% modulation can sound great actually.
     
  10. RatsoW8

    RatsoW8 Supporting Member, W9WDX ARC Member - WD8T

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    This is why I find cb so fascinating. It's fact and fiction all mashed up together ;)


    Sent from my iPhone using Tapatalk
     
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  11. Klondike Mike

    Klondike Mike Well-Known Member

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    I do have one that is on the shelf right now. I guess it will stay there a little while longer.

     
  12. GnG8d

    GnG8d Well-Known Member

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    I know, people are led to believe anything over 100% is bad.
     
  13. Shockwave

    Shockwave Sr. Member

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    That is true but what so many people overlook is that it is going to require a reasonable degree of negative peak compression (and filtering after that stage) in order to prevent those 130% negative peaks from hitting RF cutoff. Without that I'll probably hear the signal several channels away if it has any strength to it.
     
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  14. GnG8d

    GnG8d Well-Known Member

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    True, but I think there is a lot of confusion over negative peak compression and positive peak expansion. NPC is used broadly as a blanket statement when I think PPE fits better in most cases.
     
    2 people like this.
  15. M0GVZ

    M0GVZ Sr. Member

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    10 seconds examining the waveform on a scope tells you all you need to know.
     
    wavrider and RadioGuy772 like this.

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