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transmission power shown much lower than selected

Rickyfly
Rickyfly Member ✭✭
in FLEX-8000 Signature Series

Hi everyone,Could someone explain to me why, if I select 100W of power when I transmit, the meter shows me I'm transmitting at a lower power?I have no SWR or RF returns.

sdrpower.jpg

Many Thanks

Ricky

Answers

  • Erik Carling EI4KF
    Erik Carling EI4KF Member ✭✭✭✭

    Did you check actual output power? I did so with my 8400M which shows about 80 watts on the meter for 100 watts selected in a constant carrier mode. The actual output was 100 watts. It seems to be a software reporting fault. As an aside, the SWR meter is also inaccurate.

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin
    edited July 2025

    Also, check your supply voltage. You can do this by using FRStack to read the voltage meters in the radio.

    The DC voltage at the PA in the radio is directly related to the RF Power out.

    https://www.mkcmsoftware.com/Flex/Index
  • Rickyfly
    Rickyfly Member ✭✭
    immagine.png
  • Rickyfly
    Rickyfly Member ✭✭

    on trasmit

    immagine.png
  • Jim KJ3P
    Jim KJ3P Member ✭✭✭

    ….and, if you're running FT8, be sure the audio is at an appropriate level in both the app and DAX.

    You might briefly try a different mode (CW maybe) and see if you get 100%.

  • Rickyfly
    Rickyfly Member ✭✭

    Hi,

    Yes, in CW it seems to transmit at full power, but if I increase the volumes in the DAX the level cursor goes into the red over the 0!

  • Rickyfly
    Rickyfly Member ✭✭

    I tried increasing the TX volume in the dax but I don't get any power increase

  • Erik Carling EI4KF
    Erik Carling EI4KF Member ✭✭✭✭

    Are you sure you are not TXing 100 watts? I can easily demonstrate that my 8400M transmits at full power in a constant carrier mode but the meter says otherwise. On a EU DX Group chat, someone recently said the same of their 8600 and had reported it so I've been waiting for a software fix. Maybe your issue is different.

  • Rickyfly
    Rickyfly Member ✭✭

    my bird also doesn't show 100w but a little less

  • Erik Carling EI4KF
    Erik Carling EI4KF Member ✭✭✭✭

    Meter readings aside, my 8400M requires more volts than your picture showed to attain full power. I do not let it drop below 13.8 volts on TX.

  • Rickyfly
    Rickyfly Member ✭✭

    So you advise me to change the power supply?

    How many volts can the 8400M support without problems?

  • Erik Carling EI4KF
    Erik Carling EI4KF Member ✭✭✭✭

    On receive I run mine at 14.71 V which gives me 14.25 V on transmit 100 watts actual. It is rated at up to in excess of 15 V (15.87 max rated in fact).

  • Rickyfly
    Rickyfly Member ✭✭
    immagine.png immagine.png

    done but I don't have the 100W

  • Erik Carling EI4KF
    Erik Carling EI4KF Member ✭✭✭✭

    I see the same thing on the meter, it woefully under-reads. But if you also are not seeing full output on your Bird, I would check with the Help Desk on Monday and get official assistance.

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