Attention TS-430S experts, I have a problem.

Discussion in 'Radio Circuits, Repair & Performance' started by KA8RAW, Dec 6, 2019.

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  1. KA8RAW

    KA8RAW Ham Member QRZ Page

    I am repairing a TS-430S. The problem I am having is that the transmit output frequency going into the PA board is equal to the VCO output. For some reason, it is not getting mixed with the 48.055 mhz signal.

    Example: I get 76.060 mhz from the RF board out to the PA board, instead of the 28.000 mhz expected,
    so somewhere the 48.055 signal is missing and not getting mixed.

    Has anyone seen this before?
  2. KA8RAW

    KA8RAW Ham Member QRZ Page

    The TIF signal from the IF board is missing. This 8.8315 Mhz signal normally mixes with the 39.225 HET signal from the control board to produce the 48.005 signal which is supposed
    to mix with the VCO and produce my output frequency.

    I need to figure out why my 8.8315 is not being produced. any ideas?
  3. KA8RAW

    KA8RAW Ham Member QRZ Page

    What is the amplitude of the TIF signal when it is working?
  4. G4COE

    G4COE Ham Member QRZ Page

    Try measuring at the TX mixer input and output, especially the amplitude.... sounds like a mixer problem.

  5. KA8RAW

    KA8RAW Ham Member QRZ Page

    Hi Dave,
    Unfortunately the service manual lacks this info. It does list the DC voltages on the mixers and they all check okay.
    I could really use the info, I just wish the manual was a bit better.
  6. KA8RAW

    KA8RAW Ham Member QRZ Page

    I could also use the full schematic. Not the individual ones for each board, but the big fold out one.
    If someone can scan me a good copy of it, I would be grateful.
    For some reason, the online version of the service manual lacks the full schematic.
  7. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Here's the Rx and Tx level diagrams for the TS-430s. With the appropriate SSB or CW signals injected as shown you should see 100mV PP (0.1V) on the TIF signal:

  8. KA8RAW

    KA8RAW Ham Member QRZ Page

    Thanks RTF, that will come in quite handy!

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