Yaesu FT101EX... where should I start looking for these 2 problems?

Discussion in '"Boat Anchor" & Classic Equipment' started by KD0YSX, Sep 17, 2021.

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  1. HAMHOCK75

    HAMHOCK75 QRZ Member

    What kind of microphone are you using? I found the microphone needs to have at least about -60 to -50 dBV output. Many low impedance dynamic mics do not have sufficient output.
     
  2. KD0YSX

    KD0YSX Ham Member QRZ Page

    I have tried both the microphone that came with the unit (of uncertain provenance), and a Kenwood MC50. Both work on the TS520.
     
  3. HAMHOCK75

    HAMHOCK75 QRZ Member

    The MC50 should work if it is set for 50K output impedance ( output -56 dB ). If set to 600 ohm output impedance, it will not work ( -76 dB ).
     
  4. KD0YSX

    KD0YSX Ham Member QRZ Page

    It's at 50k. Too bad...
     
  5. N3RYB

    N3RYB Premium Subscriber QRZ Page

    Okay so what happens if you drive some audio into the rig via the patch port on the back. Put a tone from a computer or something into it and set the PTT to MOX and see if you get any output at any level that way. Have you cleaned the mode switch? All of the audio and control routing goes through there. If one of those connections aren't clean the AF amp won't get turned on, which is what sounds like is going on here.
     
  6. KD0YSX

    KD0YSX Ham Member QRZ Page

    I will clean it again. It certainly won't hurt anything, as long as I don't make the waferboard break down. Thanks for the word.

    I'll also figure out how to inject some tone in there.
     
  7. N3RYB

    N3RYB Premium Subscriber QRZ Page

    All of the inputs and outputs for the Audio board are easily accessible from the underside of the edge connector. Also you may want to try reseating the AF board if you haven't already.

    So the AF board, it outputs its signal from Pin 8 to the Mod/Osc board Pin 9. You can monitor the AF amp output here, you could also inject audio directly into the mod/osc board if you like. If you get modulation injecting audio at Pin 9, it's at the AF board. If you still get no modulation then its the mod/osc board.
     
  8. G3YRO

    G3YRO Ham Member QRZ Page

    As above - that's what makes these rigs one of the easiest to work on !

    Have you checked that your Mic is wired to the correct pins on the plug?

    If so, it sounds like you have a problem with the Mic Amp. I presume you have cleaned the Mic Gain pot? Have you tried simply unplugging the Audio board and cleaning the edge connector?

    While it's out, visually inspect the components around the Mic amp circuit (the photo in the Handbook will help you identify them) . . . I've never seen it here in Britain, but some of those brown capacitors have been known to split in the USA.

    Also . . . you said you adjusted the Voltage pot to set the S Meter . . . I presume you meant the S Meter pot, not the 6V Regulator pot?

    Even so, it should be reading about S9 + 40dB on the Calibrator signal on 80m ! (the correct place to set it properly is on 14.200 . . . with a Dummy load connected, it should be set to S9 + 25dB)

    Roger G3YRO
     
    N3RYB likes this.
  9. KS4W

    KS4W Premium Subscriber QRZ Page

    It's been decades since I've own either radio but it appears the mike wiring is different.
     
  10. N3RYB

    N3RYB Premium Subscriber QRZ Page

    They all seem like they're different to me :(
     

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