Which input for Yaesu FT-991?

Discussion in 'General Technical Questions and Answers' started by KB3VQT, Sep 12, 2019.

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  1. KB3VQT

    KB3VQT Ham Member QRZ Page


    I have a Yaesu FT-991 and an MFJ 4245MV Switching Power Supply. The power supply has a 40 amp output on the front and two 5 amp outputs on the back. Which one would be best for connecting my radio? The radio has two 25 amp fuses on the power line. Any help and information is appreciated.
  2. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    Stop and think!

    The unit can put out 100-watts and that usually means about twice the power input for the whole radio. A power of 200-watts requires about 14.5 amperes at 13.8 VDC. Therefore, the 5 ampere outputs won't come close to powering the transceiver. As such, your only other option is the 40 ampere jack.

    Glen, K9STH
    PY2RAF, K4AGO, W1TRY and 2 others like this.
  3. KB3VQT

    KB3VQT Ham Member QRZ Page

    Thank you. I have been out of this for over 8 years and am just coming back into it.

    73's Peter
  4. W1TRY

    W1TRY XML Subscriber QRZ Page

    Welcome back, you'll start to remember as time goes on and things begin to make sense. If in doubt, just ask.
  5. WA7PRC

    WA7PRC Ham Member QRZ Page

    To answer questions, the user manual is always a good place to start. Yaesu has it on their website (link). I suggest downloading the file(s) you're interested in. Then, for the next thing you're curious about, you'll already have the documentation. :)

    FWIW, in regard to this question, the Operating Manual (page 144) sez the FT-991 wants 23A on HF/6m at 100W output, or 15A on 144/430 MHz at 50W output. On receive, it wants 1.8A (no signal) or 2.2A (signal present). :)

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