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Is it possible to transmit with a Flex 6400 at less than 1 watt?

I use my Flex 6400 to run WSPR from time to time. I usually set the Tx Power to 1 watt and am heard literally all over the world. I would like to try even lower power but I can’t see how to do this and do not think it is possible. The fields where you set the power will not accept a decimal number lower than 1. Anyone know if this can be done?

Best Answers

  • KD0RC
    KD0RC Member, Super Elmer Moderator
    Answer ✓

    Hi David, there are a couple of options depending on how low you want to go.

    One thing that you can do is set the output power to one watt. Now use an attenuator to reduce it further. The problem is that to receive, you either need a separate antenna, or a way to switch out the attenuator.

    Another way, if you want really low power, is to use the transverter output to get from .1 mW to 10 mW out (-10 dBm to +10 dBm). The normal antenna switching in the Flex will let you use this method for transmit and receiving on the same antenna.

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin
    Answer ✓

    Another way is to set the radio to 1% and then reduce the audio drive in DAX or WSJT to the level you want. You will then have to measure your RF power with a QRP watt meter.


  • Martin AA6E
    Martin AA6E Member ✭✭✭
    Answer ✓

    You can insert a transmit attenuator that stays in the line in receive. That won't make much difference, especially on the lower HF bands.

    73 Martin AA6E


  • David N4IW
    David N4IW Member ✭✭

    Thanks Len @KD0RC and @Mike-VA3MW.

  • David N4IW
    David N4IW Member ✭✭

    Thanks everyone for your comments. I followed @Mike-VA3MW ‘s advice and was able to achieve my goal of 100-200 mW simply by turning down the drive in DAX. I also tried turning down the power slider in WSJT-X and this worked as well but only for awhile. I found that it would revert to 100% on its own for some reason. Since the DAX method worked I never tried to figure out why the slider would move on its own. Again, thanks for your comments.

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