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Thread: Softrock Ensemble RXTX and LPF placement

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  1. #1
    Join Date
    Apr 2012
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    Shropshire, England, UK.
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    Default Softrock Ensemble RXTX and LPF placement

    If I add a small linear amp to boost the very low power output of my Softrock RXTX Ensemble do I place the kits recommended LPF in between the Ensemble antenna output and the amp input? Or should I use a different LPF at the output of the amp itself and the antenna? And why please? Thanks.

  2. #2
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    SanDiego, People's Republic of California FEMA District 9
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    Quote Originally Posted by 2E0ILY View Post
    If I add a small linear amp to boost the very low power output of my Softrock RXTX Ensemble do I place the kits recommended LPF in between the Ensemble antenna output and the amp input? Or should I use a different LPF at the output of the amp itself and the antenna? And why please? Thanks.
    I would use a separate LPF at the output of the amplifier.
    You don't really want the harmonic energy in the input of the amplifier.
    When it's time, and it may be sooner than you think.

  3. #3
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    Apr 2012
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    I am not sure that I follow that, sorry. Surely ptiing the LPF *BEFORE* the amplifier would stop the harmonics entering the amplifier in the first place? Apologies if I have misunderstood, new to all of this.

  4. #4
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    Aug 2001
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    Fairhope, AL
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    You should really use the LPF for the softrock between the softrock and amp so the amp has a chance to amply a clean signal - then you MUST have a LPF on the output of the amp also. The softrock will have 2nd, 3th, 4th, etc harmonics on the output. Even with a clean input signal, the amp will also create it's own set of harmonics. Therefore, the amp will require it's own set of LPF to prevent this harmonics from being broadcast.

    73 de Ken H>

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