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RCI 2995DX no transmit power

Discussion in 'Ham Equipment' started by Crambone, Sep 12, 2019 at 4:54 PM.

  1. Crambone

    Crambone New Member

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    So I will admit my mistake and tell you I accidentally shorted TP7 to the RX Section Shielding Box. After that I lost all TX Power on all Modes. I key the mike and no movement on Bird meter with 5-watt slug. When I un-key the meter on the radio bounces but bird does nothing. No Power No Modulation



    Need some help.
     

  2. ExitThirteen

    ExitThirteen Grumpy and Cranky

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    Sounds like you took out the AM pass regulator transistor. In this particular radio, the pass regulator transistor controls the voltage and current in ALL modes. You'll have to replace Q66, which depending on the year your 2995 was built, will be either a 2SB754, or a 2SB827. It's located on the right side of the chassis bolted up on the side next to the audio IC. There may be an outside chance that you'll have to replace Q67 as well, which should be a 2SB798. Replacing those should remedy your problem.

    Try replacing Q66 first, and see if it restores output before replacing Q67.

    Let us know how you get on.


    ~Cheers~
     
  3. Crambone

    Crambone New Member

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    THANK YOU!
     
  4. Crambone

    Crambone New Member

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    I pulled Q66 and borrowed a tester and got:
    BJT-PNP
    hFe = 261
    Ube = 542mV
    IC = 6.4ma
     
  5. ExitThirteen

    ExitThirteen Grumpy and Cranky

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    That HFE doesn't seem right at all... I can check a 2SB754 and see what the HFE is on it, but I still suspect a damaged pass regulator. Do you have a spare B754 or B827? Also, what was the number on the one you pulled?



    ~Cheers~
     
  6. Crambone

    Crambone New Member

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    I pulled a B754 I don’t have any laying around so I just ordered a few.
     
  7. ExitThirteen

    ExitThirteen Grumpy and Cranky

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    I checked a couple of known good 2SB754's and I got an HFE of 101/104. I think there's something goofy with yours, I think it may have gotten damaged somehow.

    Let us know how you get on once you get your B754's in. (y)


    ~Cheers~
     
  8. Crambone

    Crambone New Member

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    Thank you I will let ya know I just looked up on the data sheet and found this, Forward Current Transfer Ratio (hFE), MIN: 70
     
    #8 Crambone, Sep 13, 2019 at 12:10 AM
    Last edited: Sep 13, 2019 at 12:18 AM

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