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Turning off AGC when running WSJT

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  • Peter Frenning [OZ1PIF]
    I always understood that it would be advantageous, but how much I didn t realize until now when I finally, after having looked for a way to do it for several
    Message 1 of 2 , Jun 30, 2007
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      I always understood that it would be advantageous, but how much I didn't
      realize until now when I finally, after having looked for a way to do it
      for several years, managed to modify my FT-847 to do just that.
      If your radio can do it - use it, if not - try to find a way to modify it.
      If it's a FT-847 - here a quick-and-dirty mod that does it:
      http://www.frenning.dk/OZ1PIF_HOMEPAGE/FT-847%20AGC-Off%20Mod.htm

      --
      Vy 73 de OZ1PIF/5Q2M, Peter

      ** CW: Who? Me? You must be joking!! **
      email: peter(no-spam-filler)@...
      http://www.frenning.dk/oz1pif.htm
      Ph. +45 4619 3239
      Snailmail:
      Peter Frenning
      Ternevej 23
      DK-4130 Viby Sj.
      Denmark
      ***********************************
    • Russ K2TXB
      Peters comments about turning off AGC are good, but for those who have no AGC switch, you can achieve much the same result by simply reducing the RF gain
      Message 2 of 2 , Jul 2, 2007
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        Peters comments about turning off AGC are good, but for those who have no AGC switch, you can achieve much the same result by simply reducing the RF gain control.  On both my FT-847 and on my TS-2000X, I always ran both FSK441 and JT65 with the RF gain backed off so that the S-meter reads about S5 with no signal present.  This also reduces the AF output from the revceiver and so the AF gain, or AF out, or computer gain controls must be advanced to re-achieve zero DB noise levels.  The receivers are no less sensitive with this setting, since the NF will be primarily set by your external preamplifier, which usually has an excess of gain.
         
        Note that even though the TS-2000X has the ability to turn off the AGC, I opted to run with it on, and use the RF gain.  I could see no difference in results, and it is nice to have the S-meter working.
         
        73, Russ K2TXB


        From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf Of Peter Frenning [OZ1PIF]
        Sent: Saturday, June 30, 2007 5:42 PM
        To: wsjtgroup@yahoogroups.com
        Subject: [wsjtgroup] Turning off AGC when running WSJT

        I always understood that it would be advantageous, but how much I didn't
        realize until now when I finally, after having looked for a way to do it
        for several years, managed to modify my FT-847 to do just that.
        If your radio can do it - use it, if not - try to find a way to modify it.
        If it's a FT-847 - here a quick-and-dirty mod that does it:
        http://www.frenning .dk/OZ1PIF_ HOMEPAGE/ FT-847%20AGC- Off%20Mod. htm

        --
        Vy 73 de OZ1PIF/5Q2M, Peter

        ** CW: Who? Me? You must be joking!! **
        email: peter(no-spam- filler)@frenning .dk
        http://www.frenning .dk/oz1pif. htm
        Ph. +45 4619 3239
        Snailmail:
        Peter Frenning
        Ternevej 23
        DK-4130 Viby Sj.
        Denmark
        ************ ********* ********* *****

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