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RE: [softrock40] Re: Softrock sensitivity.

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  • Martin Sole
    No, I m building the Lite II for 40. The early version seems to show 1k but Tony s later drawing shows 4k99. I have 1k fitted as per Jan s kit, sooooo, what s
    Message 1 of 35 , Jun 1, 2011
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      No, I’m building the Lite II for 40. The early version seems to show 1k but Tony’s later drawing shows 4k99. I have 1k fitted as per Jan’s kit, sooooo, what’s it to be, 1k or 4k99?

       

      Cheers

      Martin, HS0ZED

       

       

      From: softrock40@yahoogroups.com [mailto:softrock40@yahoogroups.com] On Behalf Of Alan
      Sent: 01 June 2011 20:54
      To: softrock40@yahoogroups.com
      Subject: Re: [softrock40] Re: Softrock sensitivity.

       

       


      ----- Original Message -----
      Subject: RE: [softrock40] Re: Softrock sensitivity.

      >
      > Thanks, so not much difference then. Back to T1 again I suppose. I'll wind
      > another one and try again.

      Martin,

      Hang on! The email text you sent was not formatted well.
      You are building for 20m?
      Then the early version has R7/8 specified as 4K99. You seem to say they are
      1K.
      That would reduce gain.

      73 Alan G4ZFQ

    • R. R. (Robby) Robson
      http://www.wb5rvz.com/sdr/sr_lite_ii/04_opamp.htm ... -- Cheers, Robby Richard R. (Robby) Robson Amateur Radio Station WB5RVZ www.wb5rvz.com
      Message 35 of 35 , Jun 2, 2011
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        http://www.wb5rvz.com/sdr/sr_lite_ii/04_opamp.htm

        On Wed, Jun 1, 2011 at 5:35 AM, Tony Parks <kb9yig@...> wrote:
         
        [Attachment(s) from Tony Parks included below]

        Hi Martin,

        The feedback resistors are supposed to be 4.99k resistors.  The schematic page for the Lite II kit is included with this note. 

        73,

        --
        Tony Parks
        kb9yig@...
        http://www.kb9yig.com
        
        


        On Wed, 2011-06-01 at 17:04 +0700, Martin Sole wrote:
         
        Okay, well I’m not convinced it’s working right yet. Here’s another thing I have just noted. In addition to the Lite I that  am referring to I also have a TXRX 6.2 partially built for 20 and 30 metres. The receiver seems noticeably livelier. Connecting an antenna makes the noise jump up a good 10dB on 30 or 20 but has no obvious effect on the noise with the Lite II. About the only thing I can figure is a difference with the op-amp. The 6.2 and 6.3 have LT6231 op amps with 4.99k resistors in the feedback but the Lite II has the same LT6231 op-amp (changed from a TLV2462) but with 1k resistors in the feedback. It also has 1 resistors in the op –amp output. Just wondering about that.

         

        Regards

        Martin, HS0ZED

         

         

        From: softrock40@yahoogroups.com [mailto:softrock40@yahoogroups.com] On Behalf Of Alan
        Sent: 01 June 2011 15:41
        To: softrock40@yahoogroups.com
        Subject: Re: [softrock40] Re: Softrock sensitivity.


         

         


        ----- Original Message -----
        Subject: RE: [softrock40] Re: Softrock sensitivity.

        >
        > I'm still left with not being able to hear much below 1uV and that seems
        > to
        > me to be about 20dB deafer than I would expect.
        >

        Martin,
        Sorry but I'm not familiar with how the figures compare with actual
        audibility.
        If you search the messages you will find what others have said.
        for example <http://groups.yahoo.com/group/softrock40/message/53438>

        73 Alan G4ZFQ






        --
        Cheers,
        Robby
         
        Richard R. (Robby) Robson
        Amateur Radio Station WB5RVZ

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