Yaesu FT 450D will not transmit on LSB or USB part of the time

Discussion in 'General Technical Questions and Answers' started by W9EMM, Mar 9, 2020.

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  1. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Remember that checking voltage "at the radio" is not the same as checking it coming from the power supply. I think that was the point in the earlier post.
  2. W9EMM

    W9EMM Ham Member QRZ Page

    yes I know that I used my meter to check.
  3. N2ZD

    N2ZD Ham Member QRZ Page

    Bad connection =12v
    Good connection =12v

    Testing with a voltmeter means nothing.

    A typical HF radio draws 18-24 amps in transmit at 100 watts give or take. You need to check current draw. Yaesu DC cables are notoriously bad in that they use aluminum and other crappy metals in the fuse holders.
    After a while, the holders give up the ghost to minute bits of oxidation which will pass 12v but not 20 or so amps. So start from scratch, remove and clean the connections at the supply. Then clean the fuse holders and fuses. Then clean the jack and dc connector. Make sure the fuse holders grab the fuses tightly, and the rear jack does the same.
    WB5YUZ likes this.
  4. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    All these things are common problems with Icom power cords, also.
  5. AI3V

    AI3V Ham Member QRZ Page

    Your symptoms indicate a problem in either the microphone(s) or in the microphone circitry in the rig.

    Do you have any way to either test your microphones on a known working radio, or to obtain a known good microphone?

    The fact your radio outputs full power in other modes means the transmitters power amplifier is ok, as well as the power supply and power wiring.

    Along with a master reset, things to check are microphone gain settings on the rig, as well as the various mic processor settings.

    Also, check to see that you havn't accidentally switched the rear panel audio in on, instead of the front panel microphone.

  6. W9EMM

    W9EMM Ham Member QRZ Page

    Thanks I will check your ideas out.

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