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Flex 8400M

Roger
Roger Member ✭✭
edited October 2025 in FLEX-6000 Signature Series

My recently aquired 8400M shows S3 on the Smeter with no antenna or a dummy load.

Is this correct? and why?

Thanks Roger G0IUW

Answers

  • Trucker
    Trucker Member ✭✭✭✭

    Normal. It is the internally generated noise level of the ADC's. ( Analog Digital Converter)

    It has no effect on the correct level ( S meter readings) of the meter with the antenna connected.

    James

    WD5GWY

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Hi Roger, Yes, as James said, that is normal. As an experiment, narrow the bandwidth significantly, and you will see the no-signal S meter reading go down. If I have an S6 noise level with a 3 KHz filter, I get an S3 reading with a 50 Hz filter. It is the total energy in the passband that is calculated to get an S meter reading.

  • Roger
    Roger Member ✭✭

    Thanks Guys for the useful info… I,m grateful

    Roger G0IUW

  • n0ypd
    n0ypd Member ✭✭

    I have the same thing. Glad someone asked.

  • John KB4DU
    John KB4DU Member ✭✭✭✭

    The flex accurately indicates the signal level at the antenna terminal, compared to most other radios that indicate something based on the signal level somewhere in the I.F. Chain, and are usually not linear.

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