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RF gain issue

K6JV Member ✭✭

I have always had the RF gain at zero which would have the S meter at 5 with just the noise. Now I have to increase the RF gain to maximum to hear anything. Have I lost something in the front end of the receiver? It is a 6400 via Smartlink to a remote site.


  • Lasse SM5GLC
    Lasse SM5GLC Member ✭✭✭

    Do your S-meter still show S5? Are the s/w still show you are using the same antenna port as earlier? What does the SWR show when you transmit? I ask as this may help us to spot the problem.

    /Lasse SM5GLC

  • K6JV
    K6JV Member ✭✭

    The SWR was fine and no the S meter showed S1 when the RF gain was all the way done. Suddenly now the radio is almost normal except the RF gain has no effect on the S meter reading.

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    That is proper operation - the RF Gain should not affect the S-meter reading. There is a section in the SmartSDR manual on adjusting the RF Gain. I find that I occasionally need to adjust it depending on band conditions and time of day.

  • Lasse SM5GLC
    Lasse SM5GLC Member ✭✭✭

    Just to add one thing, by altering the BW you will see different reading on the S-meter. Going from 3kHz down to 300 Hz will show almost a 2 s-unit drop (i.e. 10 dB). This is for noise only.

  • John KB4DU
    John KB4DU Member ✭✭✭✭

    The S meter displays the signal strength (all signals the selected bandwidth) , unlike a traditional radio that measures the agc in the if stage to drive the S meter. On any radio if changing the rf gain affects the S meter, the s meter is inaccurate.

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


    A few questions.

    RFGain or AGC-T

    What are the settings for both.

    What bands?

    What procedure are you using to adjust your AGC-T?

    73, Mike

  • K6JV
    K6JV Member ✭✭

    HI Mike, whatever the issue was with the Maestro it fixed itself!

    I use the published procedure to adjust AGC-T.

    The issue was happening on all bands. The issue was that the S meter fell to S1 and the sensitivity of the receiver was way down. Adjusting the RF gain made the S meter go up and down.

    The radio suddenly popped back to normal sensitivity and the S meter back to it's usual S5.


  • gbo
    gbo Member, Unconfirmed
    Hello, do you find any solution for this rf-gain issue? My new remote station with Flex 6600 is doing exactly same and all bands. Radio just have been only one week in my remote station and brand new. I was working remote, using internal antenna tuner and suddenly radio lost all signals. When i turn rf-gain to maximum preamp, signals came up. AGC-T is adjusted as usual. I tried to reset all tuner memories, factory reset whole radio and no luck. I have another Flex 6400 and it works just fine. Any ideas what might be the issue with 6600?
  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin


    This is not normal and not something we normally see. Please open a support ticket. If you can take a video of it failing, that will really help out the support team understand what is happening.

    Don't forget to say what version of the software you are using.


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