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Weak Signal Performance of Soundcard Interfaces

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  • Les Rayburn
    The August QST Hints & Kinks column contains a modification to the Signalink USB interface designed to improve it s internal noise floor, and increase it s
    Message 1 of 22 , Jul 16, 2014
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      The August QST "Hints & Kinks" column contains a modification to the
      Signalink USB interface designed to improve it's internal noise floor,
      and increase it's performance for weak signal operation such as EME and
      meteor scatter. The modification suggested by Mat Breton, AB8VJ is
      straight-forward, and well written.

      Mat also references additional modifications suggested by Peter
      Frenning, OZ1PIF which can be found at:
      http://www.frenning.dk/OZ1PIF_HOMEPAGE/SignaLinkUSB-mods.html

      Peter's modifications are a bit more "surgery" than I'm comfortable
      performing these days. But it did get me thinking about my current
      set-up which uses a SignaLink USB interface along with an Icom IC-910H
      for Meteor Scatter work on WSJT. I'm wondering now if I might improve
      things by switching interfaces. Has anyone compared the commercial
      interfaces available, and evaluated their weak signal performance on
      modes like EME or Meteor Scatter?

      I'd be curious about any results or recommendations that the group might
      have.


      --
      --
      73,

      Les Rayburn, N1LF
      121 Mayfair Park
      Maylene, AL 35114
      EM63nf

      6M VUCC #1712
      AMSAT #38965
      Grid Bandits #222
      Southeastern VHF Society
      Central States VHF Society Life Member
      Six Club #2484

      Active on 6 Meters thru 1296, 10GHz & Light
    • chas cartmel
      Les Not an answer to your specific question, but on a general basis I found that using a better soundcard, an internal Soundblaster, rather than an external
      Message 2 of 22 , Jul 17, 2014
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        Les

        Not an answer to your specific question, but on a general basis I found that using a better soundcard, an internal Soundblaster, rather than an external USB card improved my reception dramatically by reducing the noise floor. This was noticeable both audibly and visually on the waterfall. I switched when PSK was my main data mode but i am sure the impact on WSJT would be the same or greater.

         

        73

        Charlie

        www.G4EST.me.uk

         

        From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf Of Les Rayburn les@... [wsjtgroup]
        Sent: 17 July 2014 03:17
        To: WSJT Group; vhf@...
        Subject: [wsjtgroup] Weak Signal Performance of Soundcard Interfaces

         

         

        The August QST "Hints & Kinks" column contains a modification to the
        Signalink USB interface designed to improve it's internal noise floor,
        and increase it's performance for weak signal operation such as EME and
        meteor scatter. The modification suggested by Mat Breton, AB8VJ is
        straight-forward, and well written.

        Mat also references additional modifications suggested by Peter
        Frenning, OZ1PIF which can be found at:
        http://www.frenning.dk/OZ1PIF_HOMEPAGE/SignaLinkUSB-mods.html

        Peter's modifications are a bit more "surgery" than I'm comfortable
        performing these days. But it did get me thinking about my current
        set-up which uses a SignaLink USB interface along with an Icom IC-910H
        for Meteor Scatter work on WSJT. I'm wondering now if I might improve
        things by switching interfaces. Has anyone compared the commercial
        interfaces available, and evaluated their weak signal performance on
        modes like EME or Meteor Scatter?

        I'd be curious about any results or recommendations that the group might
        have.

        --
        --
        73,

        Les Rayburn, N1LF
        121 Mayfair Park
        Maylene, AL 35114
        EM63nf

        6M VUCC #1712
        AMSAT #38965
        Grid Bandits #222
        Southeastern VHF Society
        Central States VHF Society Life Member
        Six Club #2484

        Active on 6 Meters thru 1296, 10GHz & Light

      • Jon Pearl - W4ABC
        Hi Les, I m using the microHam microKeyer II. You may want to give it some consideration. - http://microham-usa.com/store/product-info.php?pid1.html Their
        Message 3 of 22 , Jul 17, 2014
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          Hi Les,

          I'm using the microHam microKeyer II.  You may want to give it some consideration. - http://microham-usa.com/store/product-info.php?pid1.html

          Their literature states the following:
          Ultra low noise: 
          - The sound circuits are designed with special attention to low noise 
          - The receive noise floor in microKEYER II is lower than any value priced 
            
          sound card or similar amateur product. 
          Dynamic range rivals that of professional products.
          - Special circuit design maintains full dynamic range and low noise floor   
               with all radios - both high level and low level outputs.  


          eHam scorecard: http://www.eham.net/reviews/detail/6972


          73,



          Jon Pearl - W4ABC
          www.w4abc.com


          On 7/16/2014 10:16 PM, Les Rayburn wrote:
          The August QST "Hints & Kinks" column contains a modification to the Signalink USB interface designed to improve it's internal noise floor, and increase it's performance for weak signal operation such as EME and meteor scatter. The modification suggested by Mat Breton, AB8VJ is straight-forward, and well written.

          Mat also references additional modifications suggested by Peter Frenning, OZ1PIF which can be found at:
          http://www.frenning.dk/OZ1PIF_HOMEPAGE/SignaLinkUSB-mods.html

          Peter's modifications are a bit more "surgery" than I'm comfortable performing these days. But it did get me thinking about my current set-up which uses a SignaLink USB interface along with an Icom IC-910H for Meteor Scatter work on WSJT. I'm wondering now if I might improve things by switching interfaces. Has anyone compared the commercial interfaces available, and evaluated their weak signal performance on modes like EME or Meteor Scatter?

          I'd be curious about any results or recommendations that the group might have.






          This email is free from viruses and malware because avast! Antivirus protection is active.


        • Jim Brown
          I have posted several times on my work on this. I m a retired audio professional, and several years ago looked at several audio products designed for home
          Message 4 of 22 , Jul 17, 2014
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            I have posted several times on my work on this. I'm a retired audio
            professional, and several years ago looked at several audio products
            designed for home studio use for this application.

            I settled on two of them on the basis of specs and my knowledge of the
            companies that make them, bought them, and tested them extensively. The
            two I bought are the Numark stereo USB, and the Tascam US100. The two
            performed equally well, and roughly twice as good as the internal sound
            card in my Thinkpad laptops.

            I used JT65-HF as a test bed, because it has a multi-decoder and gives
            dB reports for each decode. WSJT-X was not yet available. I fed the
            output of my K3 to the decoder under test to one laptop, and also to the
            internal sound card of another Thinkpad. Both USB interfaces produced
            roughly twice as many decodes in a pass as did the internal sound card.
            Both decoders often decoded signals in the -20 dB range. The Thinkpads
            were running XP Pro. Both products use standard Windows drivers. Next,
            I set up the two decoders side by side, each driving its own Thinkpad,
            and compared performance on MANY decode passes. They performed equally
            well -- on any given pass, one might miss a signal that the other
            decoded, but never more than one, and neither was better than the other.

            The Numark unit is still available. The Tascam US100 has been replaced
            by a similar model with a new number. I paid about $35 for the Numark
            and about $75 for the Tascam, at B&H Photo. One current Tascam product
            is the US125. The only virtue of the Tascam is that it provides more
            input options and more knobs.

            I use the Tascam on my main radio, and the Numark on my second radio for
            SO2R (single operator, two radio) RTTY contesting.

            Note that these units are simply good audio interfaces, properly built
            without Pin One Problems that can cause hum, buzz, and RFI. They do NOT
            do rig control.

            73, Jim K9YC

            On 7/16/2014 7:16 PM, Les Rayburn les@... [wsjtgroup] wrote:
            > The August QST "Hints & Kinks" column contains a modification to the
            > Signalink USB interface designed to improve it's internal noise floor,
            > and increase it's performance for weak signal operation such as EME and
            > meteor scatter. The modification suggested by Mat Breton, AB8VJ is
            > straight-forward, and well written.
            >
            > Mat also references additional modifications suggested by Peter
            > Frenning, OZ1PIF which can be found at:
            > http://www.frenning.dk/OZ1PIF_HOMEPAGE/SignaLinkUSB-mods.html
            >
            > Peter's modifications are a bit more "surgery" than I'm comfortable
            > performing these days. But it did get me thinking about my current
            > set-up which uses a SignaLink USB interface along with an Icom IC-910H
            > for Meteor Scatter work on WSJT. I'm wondering now if I might improve
            > things by switching interfaces. Has anyone compared the commercial
            > interfaces available, and evaluated their weak signal performance on
            > modes like EME or Meteor Scatter?
            >
            > I'd be curious about any results or recommendations that the group might
            > have.
            >
            >
          • N7RJN
            Per the Tascam web site, the US125 has apparently been discontinued and replaced by the US366. From: Jim Brown k9yc@audiosystemsgroup.com [wsjtgroup]
            Message 5 of 22 , Jul 17, 2014
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              Per the Tascam web site, the US125 has apparently been discontinued and replaced by the US366.

              From: "Jim Brown k9yc@... [wsjtgroup]" <wsjtgroup-noreply@yahoogroups.com>
              Reply-To: <k9yc@...>
              Date: Thursday, July 17, 2014 at 9:28
              To: <les@...>, WSJT Group <wsjtgroup@yahoogroups.com>, "vhf@..." <vhf@...>
              Subject: Re: [wsjtgroup] Weak Signal Performance of Soundcard Interfaces

               

              I have posted several times on my work on this. I'm a retired audio
              professional, and several years ago looked at several audio products
              designed for home studio use for this application.

              I settled on two of them on the basis of specs and my knowledge of the
              companies that make them, bought them, and tested them extensively. The
              two I bought are the Numark stereo USB, and the Tascam US100. The two
              performed equally well, and roughly twice as good as the internal sound
              card in my Thinkpad laptops.

              I used JT65-HF as a test bed, because it has a multi-decoder and gives
              dB reports for each decode. WSJT-X was not yet available. I fed the
              output of my K3 to the decoder under test to one laptop, and also to the
              internal sound card of another Thinkpad. Both USB interfaces produced
              roughly twice as many decodes in a pass as did the internal sound card.
              Both decoders often decoded signals in the -20 dB range. The Thinkpads
              were running XP Pro. Both products use standard Windows drivers. Next,
              I set up the two decoders side by side, each driving its own Thinkpad,
              and compared performance on MANY decode passes. They performed equally
              well -- on any given pass, one might miss a signal that the other
              decoded, but never more than one, and neither was better than the other.

              The Numark unit is still available. The Tascam US100 has been replaced
              by a similar model with a new number. I paid about $35 for the Numark
              and about $75 for the Tascam, at B&H Photo. One current Tascam product
              is the US125. The only virtue of the Tascam is that it provides more
              input options and more knobs.

              I use the Tascam on my main radio, and the Numark on my second radio for
              SO2R (single operator, two radio) RTTY contesting.

              Note that these units are simply good audio interfaces, properly built
              without Pin One Problems that can cause hum, buzz, and RFI. They do NOT
              do rig control.

              73, Jim K9YC

              On 7/16/2014 7:16 PM, Les Rayburn les@... [wsjtgroup] wrote:
              > The August QST "Hints & Kinks" column contains a modification to the
              > Signalink USB interface designed to improve it's internal noise floor,
              > and increase it's performance for weak signal operation such as EME and
              > meteor scatter. The modification suggested by Mat Breton, AB8VJ is
              > straight-forward, and well written.
              >
              > Mat also references additional modifications suggested by Peter
              > Frenning, OZ1PIF which can be found at:
              > http://www.frenning.dk/OZ1PIF_HOMEPAGE/SignaLinkUSB-mods.html
              >
              > Peter's modifications are a bit more "surgery" than I'm comfortable
              > performing these days. But it did get me thinking about my current
              > set-up which uses a SignaLink USB interface along with an Icom IC-910H
              > for Meteor Scatter work on WSJT. I'm wondering now if I might improve
              > things by switching interfaces. Has anyone compared the commercial
              > interfaces available, and evaluated their weak signal performance on
              > modes like EME or Meteor Scatter?
              >
              > I'd be curious about any results or recommendations that the group might
              > have.
              >
              >

            • Les Rayburn
              Jim, Thank you for this. I ve heard similar recommendations for the SoundDevices USBPre2 external interface. The problem with all these is that they don t
              Message 6 of 22 , Jul 17, 2014
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                Jim,

                Thank you for this. I've heard similar recommendations for the
                SoundDevices USBPre2 external interface. The problem with all these is
                that they don't handle things like PTT, and they're not easy for most of
                us to interface with our rigs. I'm curious as to how you managed PTT.

                I'd love to see QST do technical reviews or comparisons of soundcard
                interfaces that are commercially available with an eye towards Weak
                Signal work. Unfortunately, WSJT and digital modes in general are
                completely dominated by HF operators at the moment. At those
                frequencies, the internal noise floor of a soundcard interface is
                trivial or not a factor at all. But on VHF weak signal modes, such as
                EME a db or two is the difference between a contact and a bust.

                Manufacturers don't help because most don't publish schematics or
                reliable specifications in an effort to safeguard their business
                practices. This makes it hard to compare apples with oranges. I'm a bit
                surprised that the EME community hasn't published more on this topic, at
                least that I can find on the web or back issues of DUBUS.

                73,


                Les Rayburn, N1LF
                121 Mayfair Park
                Maylene, AL 35114
                EM63nf

                6M VUCC #1712
                AMSAT #38965
                Grid Bandits #222
                Southeastern VHF Society
                Central States VHF Society Life Member
                Six Club #2484

                Active on 6 Meters thru 1296, 10GHz & Light


                On 7/17/2014 11:28 AM, Jim Brown wrote:
                > I have posted several times on my work on this. I'm a retired audio
                > professional, and several years ago looked at several audio products
                > designed for home studio use for this application.
                >
                > I settled on two of them on the basis of specs and my knowledge of the
                > companies that make them, bought them, and tested them extensively.
                > The two I bought are the Numark stereo USB, and the Tascam US100. The
                > two performed equally well, and roughly twice as good as the internal
                > sound card in my Thinkpad laptops.
                >
                > I used JT65-HF as a test bed, because it has a multi-decoder and gives
                > dB reports for each decode. WSJT-X was not yet available. I fed the
                > output of my K3 to the decoder under test to one laptop, and also to
                > the internal sound card of another Thinkpad. Both USB interfaces
                > produced roughly twice as many decodes in a pass as did the internal
                > sound card. Both decoders often decoded signals in the -20 dB range.
                > The Thinkpads were running XP Pro. Both products use standard Windows
                > drivers. Next, I set up the two decoders side by side, each driving
                > its own Thinkpad, and compared performance on MANY decode passes. They
                > performed equally well -- on any given pass, one might miss a signal
                > that the other decoded, but never more than one, and neither was
                > better than the other.
                >
                > The Numark unit is still available. The Tascam US100 has been replaced
                > by a similar model with a new number. I paid about $35 for the Numark
                > and about $75 for the Tascam, at B&H Photo. One current Tascam product
                > is the US125. The only virtue of the Tascam is that it provides more
                > input options and more knobs.
                >
                > I use the Tascam on my main radio, and the Numark on my second radio
                > for SO2R (single operator, two radio) RTTY contesting.
                >
                > Note that these units are simply good audio interfaces, properly built
                > without Pin One Problems that can cause hum, buzz, and RFI. They do
                > NOT do rig control.
                >
                > 73, Jim K9YC
                >
                > On 7/16/2014 7:16 PM, Les Rayburn les@... [wsjtgroup] wrote:
                >> The August QST "Hints & Kinks" column contains a modification to the
                >> Signalink USB interface designed to improve it's internal noise floor,
                >> and increase it's performance for weak signal operation such as EME and
                >> meteor scatter. The modification suggested by Mat Breton, AB8VJ is
                >> straight-forward, and well written.
                >>
                >> Mat also references additional modifications suggested by Peter
                >> Frenning, OZ1PIF which can be found at:
                >> http://www.frenning.dk/OZ1PIF_HOMEPAGE/SignaLinkUSB-mods.html
                >>
                >> Peter's modifications are a bit more "surgery" than I'm comfortable
                >> performing these days. But it did get me thinking about my current
                >> set-up which uses a SignaLink USB interface along with an Icom IC-910H
                >> for Meteor Scatter work on WSJT. I'm wondering now if I might improve
                >> things by switching interfaces. Has anyone compared the commercial
                >> interfaces available, and evaluated their weak signal performance on
                >> modes like EME or Meteor Scatter?
                >>
                >> I'd be curious about any results or recommendations that the group might
                >> have.
                >>
                >>
                >
                >


                --
                --
                73,

                Les Rayburn, N1LF
                121 Mayfair Park
                Maylene, AL 35114
                EM63nf

                6M VUCC #1712
                AMSAT #38965
                Grid Bandits #222
                Southeastern VHF Society
                Central States VHF Society Life Member
                Six Club #2484

                Active on 6 Meters thru 1296, 10GHz & Light
              • Kai
                There was some chatter about this on the RTTY reflector... Kok Chen, W7AY, I copied Chen on this, perhaps he will comment. Chen, can you comment of sound card
                Message 7 of 22 , Jul 17, 2014
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                  There was some chatter about this on the RTTY reflector... Kok Chen, W7AY,  I
                  copied Chen on this, perhaps he will comment.

                  Chen, can you comment of sound card noise performance?

                  73
                  Kai, KE4PT


                  On 7/17/2014 12:58 PM, Les Rayburn les@... [wsjtgroup] wrote:
                  Jim,
                  
                  Thank you for this. I've heard similar recommendations for the 
                  SoundDevices USBPre2 external interface. The problem with all these is 
                  that they don't handle things like PTT, and they're not easy for most of 
                  us to interface with our rigs. I'm curious as to how you managed PTT.
                  
                  I'd love to see QST do technical reviews or comparisons of soundcard 
                  interfaces that are commercially available with an eye towards Weak 
                  Signal work. Unfortunately, WSJT and digital modes in general are 
                  completely dominated by HF operators at the moment. At those 
                  frequencies, the internal noise floor of a soundcard interface is 
                  trivial or not a factor at all. But on VHF weak signal modes, such as 
                  EME a db or two is the difference between a contact and a bust.
                  
                  Manufacturers don't help because most don't publish schematics or 
                  reliable specifications in an effort to safeguard their business 
                  practices. This makes it hard to compare apples with oranges. I'm a bit 
                  surprised that the EME community hasn't published more on this topic, at 
                  least that I can find on the web or back issues of DUBUS.
                  
                  73,
                  
                  
                  Les Rayburn, N1LF
                  121 Mayfair Park
                  Maylene, AL 35114
                    EM63nf
                  
                  6M VUCC #1712
                  AMSAT #38965
                  Grid Bandits #222
                  Southeastern VHF Society
                  Central States VHF Society Life Member
                  Six Club #2484
                  
                  Active on 6 Meters thru 1296, 10GHz & Light
                  
                  
                  On 7/17/2014 11:28 AM, Jim Brown wrote:
                  
                  I have posted several times on my work on this. I'm a retired audio 
                  professional, and several years ago looked at several audio products 
                  designed for home studio use for this application.
                  
                  I settled on two of them on the basis of specs and my knowledge of the 
                  companies that make them, bought them, and tested them extensively.  
                  The two I bought are the Numark stereo USB, and the Tascam US100. The 
                  two performed equally well, and roughly twice as good as the internal 
                  sound card in my Thinkpad laptops.
                  
                  I used JT65-HF as a test bed, because it has a multi-decoder and gives 
                  dB reports for each decode. WSJT-X was not yet available.  I fed the 
                  output of my K3 to the decoder under test to one laptop, and also to 
                  the internal sound card of another Thinkpad. Both USB interfaces 
                  produced roughly twice as many decodes in a pass as did the internal 
                  sound card. Both decoders often decoded signals in the -20 dB range. 
                  The Thinkpads were running XP Pro. Both products use standard Windows 
                  drivers.  Next, I set up the two decoders side by side, each driving 
                  its own Thinkpad, and compared performance on MANY decode passes. They 
                  performed equally well -- on any given pass, one might miss a signal 
                  that the other decoded, but never more than one, and neither was 
                  better than the other.
                  
                  The Numark unit is still available. The Tascam US100 has been replaced 
                  by a similar model with a new number.  I paid about $35 for the Numark 
                  and about $75 for the Tascam, at B&H Photo. One current Tascam product 
                  is the US125.  The only virtue of the Tascam is that it provides more 
                  input options and more knobs.
                  
                  I use the Tascam on my main radio, and the Numark on my second radio 
                  for SO2R (single operator, two radio) RTTY contesting.
                  
                  Note that these units are simply good audio interfaces, properly built 
                  without Pin One Problems that can cause hum, buzz, and RFI. They do 
                  NOT do rig control.
                  
                  73, Jim K9YC
                  
                  On 7/16/2014 7:16 PM, Les Rayburn les@... [wsjtgroup] wrote:
                  
                  The August QST "Hints & Kinks" column contains a modification to the
                  Signalink USB interface designed to improve it's internal noise floor,
                  and increase it's performance for weak signal operation such as EME and
                  meteor scatter. The modification suggested by Mat Breton, AB8VJ is
                  straight-forward, and well written.
                  
                  Mat also references additional modifications suggested by Peter
                  Frenning, OZ1PIF which can be found at:
                  http://www.frenning.dk/OZ1PIF_HOMEPAGE/SignaLinkUSB-mods.html
                  
                  Peter's modifications are a bit more "surgery" than I'm comfortable
                  performing these days. But it did get me thinking about my current
                  set-up which uses a SignaLink USB interface along with an Icom IC-910H
                  for Meteor Scatter work on WSJT. I'm wondering now if I might improve
                  things by switching interfaces. Has anyone compared the commercial
                  interfaces available, and evaluated their weak signal performance on
                  modes like EME or Meteor Scatter?
                  
                  I'd be curious about any results or recommendations that the group might
                  have.
                  
                  
                  
                  
                  
                  
                  

                • Bill
                  I looked at audio interfaces a few years ago myself. This is from memory... Most interfaces for ham equipment use the Burr-Brown IC. This chip combines the
                  Message 8 of 22 , Jul 17, 2014
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                    I looked at audio interfaces a few years ago myself.
                    This is from memory...

                    Most interfaces for ham equipment use the Burr-Brown IC. This chip
                    combines the ADCs, DACs and USB functions into one. It is a good
                    performer, with reasonable SNR. It is limited to 16 bits, and the
                    optimum sample rate is 48 kHz. They identify as "USB Audio CODEC". The
                    built in USB audio in modern rigs all use this IC. I have found it
                    capable in the noisy environment of most HF comms.

                    Pro-Audio interfaces use much a more capable audio chain. The standard
                    is 24 bits at 192 kHz. For many years I have used a Roland FA-66 with
                    very good results. They can be used single ended, but a transformer at
                    the radio to balanced with shielded wire to the interface is much
                    better. The FA-66 has been around for many years, but has undergone
                    brand name changes. I've seen it as Edirol and Cakewalk.

                    Unfortunately, with the proliferation of the Burr-Brown IC, I never did
                    find a PC program that could use the capabilities of the FA-66. While 48
                    kHz sampling is more than good enough for our use (audio frequencies of
                    less than 5 kHz), 24 bits would give a big increase in dynamic range.
                    Maybe a future version of WSJT-X might have that capability?

                    Be careful of the pro audio interfaces. The vast majority are actually
                    mixers. While they have multiple audio inputs, there is usually only one
                    actual device on the computer end, which means even though they list a
                    lot of in/out, you will only get to use it with one radio at a time.

                    The FA-66 has multiple devices (I think 3) so you can use it with more
                    than one radio. I used mine with an FT-736R with a transformer and an
                    IC-7800 using TOSLink optical. Both can be running at the same time.

                    My transmit signalling is done via RTS on the serial port. Note that
                    Icoms don't give you this internally, you have to wire it through a
                    level converter yourself. The new Yaesu FTDX3000 has an extra internal
                    serial port (via USB) that you can use for the TX signal.

                    I have also used the SL-USB with good results. The older ones do have
                    noise on the low end, but I don't use those lower frequencies, and they
                    can be modded to reduce the noise greatly. The newer one I have doesn't
                    suffer from that problem. I do use inductors for the jumpers, which
                    kills off any stray RF quite well.

                    Hope this helps.
                    Bill KC7I

                    PS for Kai, if you can borrow a Signalink to replace yours temporarily,
                    it may show if there is a defect in your hardware. If replacing it
                    doesn't help, the problem is probably a driver issue.
                  • Jim Brown
                    ... Sound Devices is a very good company, but their gear is a lot pricier, and while their performance is better in pro audio applications, it doesn t matter
                    Message 9 of 22 , Jul 17, 2014
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                      On 7/17/2014 9:58 AM, Les Rayburn les@... [wsjtgroup] wrote:
                      > Thank you for this. I've heard similar recommendations for the
                      > SoundDevices USBPre2 external interface. The problem with all these is
                      > that they don't handle things like PTT, and they're not easy for most of
                      > us to interface with our rigs. I'm curious as to how you managed PTT.

                      Sound Devices is a very good company, but their gear is a lot pricier,
                      and while their performance is better in pro audio applications, it
                      doesn't matter for ham radio.

                      I forgot to mention that with WSJT-X, I'm seeing JT65 decodes at -22 and
                      -23, and JT9 decodes at -24.

                      I've always used VOX for all digital modes, it works fine. I do
                      thousands of RTTY Qs a year in contests, hundreds using WSJT and WSJT-X.
                      I use MMTTY and 2Tone for RTTY, and N1MM with MMTTY and 2Tone for
                      contesting. Nearly all modern rigs have internal circuitry that delays
                      TX, and also PTT for an amplifier for 10msec or so for T/R relays to
                      pull in, so there are no issues with hot switching.

                      IMO, the difference between 16 bit and 24 bit does not matter for ham
                      radio, simply because signal to noise is determined by noise coming in
                      on the antenna, not noise from a pro mic in a quiet space. What matters
                      is the linearity of the A/D over the range of signal amplitudes that it
                      sees. Any assertion that 24-bit A/D matters ought to be accompanied by
                      the same sort of on-the-air testing that I described. To make it clear,
                      I looked at many hundreds of decode passes on several HF bands and 160M.

                      As to current Tascam model numbers -- I suggest poking around the B&H
                      website for Tascam USB and see what comes up. Sweetwater and Full
                      Compass are two other first rate on-line vendors.

                      73, Jim K9YC
                    • Joe Subich, W4TV
                      There have been several reviews by weak signal users - primarily European EME and MS users - of the microHAM interfaces. I leave that to others to avoid the
                      Message 10 of 22 , Jul 17, 2014
                      • 0 Attachment
                        There have been several reviews by weak signal users - primarily
                        European EME and MS users - of the microHAM interfaces. I leave
                        that to others to avoid the obvious issues of personal interest.

                        However, for most purposes 16 bit sampling is more than sufficient
                        if the sound card is well designed with proper power supply bypassing
                        and regulation. The 90 dB-plus dynamic range is more than enough to
                        handle from the absolute noise floor of the transceiver to signals
                        equivalent to S9 +20 dB and represents an audio input range from
                        2V RMS to less than 30 microvolts RMS. The key to using this range
                        is to keep the power supply and reference voltages to the ADC and
                        any audio preamplifier absolutely clean and stable - something that
                        many "low price" amateur products fail to accomplish.

                        While 24 bit products with their custom built ADC ans special drivers
                        may provide more dynamic range they are typically limited to 2V RMS
                        input (or the transceiver can't produce more than 2V RMS cleanly)
                        and most of the added resolution is lost to unavoidable circuit noise.
                        That may be somewhat different with SDR technology but downconversion
                        I/Q receivers have other issues with both front end dynamic range and
                        user interfaces.

                        73,

                        ... Joe, W4TV


                        On 2014-07-17 1:48 PM, Bill bill@... [wsjtgroup] wrote:
                        > I looked at audio interfaces a few years ago myself.
                        > This is from memory...
                        >
                        > Most interfaces for ham equipment use the Burr-Brown IC. This chip
                        > combines the ADCs, DACs and USB functions into one. It is a good
                        > performer, with reasonable SNR. It is limited to 16 bits, and the
                        > optimum sample rate is 48 kHz. They identify as "USB Audio CODEC". The
                        > built in USB audio in modern rigs all use this IC. I have found it
                        > capable in the noisy environment of most HF comms.
                        >
                        > Pro-Audio interfaces use much a more capable audio chain. The standard
                        > is 24 bits at 192 kHz. For many years I have used a Roland FA-66 with
                        > very good results. They can be used single ended, but a transformer at
                        > the radio to balanced with shielded wire to the interface is much
                        > better. The FA-66 has been around for many years, but has undergone
                        > brand name changes. I've seen it as Edirol and Cakewalk.
                        >
                        > Unfortunately, with the proliferation of the Burr-Brown IC, I never did
                        > find a PC program that could use the capabilities of the FA-66. While 48
                        > kHz sampling is more than good enough for our use (audio frequencies of
                        > less than 5 kHz), 24 bits would give a big increase in dynamic range.
                        > Maybe a future version of WSJT-X might have that capability?
                        >
                        > Be careful of the pro audio interfaces. The vast majority are actually
                        > mixers. While they have multiple audio inputs, there is usually only one
                        > actual device on the computer end, which means even though they list a
                        > lot of in/out, you will only get to use it with one radio at a time.
                        >
                        > The FA-66 has multiple devices (I think 3) so you can use it with more
                        > than one radio. I used mine with an FT-736R with a transformer and an
                        > IC-7800 using TOSLink optical. Both can be running at the same time.
                        >
                        > My transmit signalling is done via RTS on the serial port. Note that
                        > Icoms don't give you this internally, you have to wire it through a
                        > level converter yourself. The new Yaesu FTDX3000 has an extra internal
                        > serial port (via USB) that you can use for the TX signal.
                        >
                        > I have also used the SL-USB with good results. The older ones do have
                        > noise on the low end, but I don't use those lower frequencies, and they
                        > can be modded to reduce the noise greatly. The newer one I have doesn't
                        > suffer from that problem. I do use inductors for the jumpers, which
                        > kills off any stray RF quite well.
                        >
                        > Hope this helps.
                        > Bill KC7I
                        >
                        > PS for Kai, if you can borrow a Signalink to replace yours temporarily,
                        > it may show if there is a defect in your hardware. If replacing it
                        > doesn't help, the problem is probably a driver issue.
                        >
                        >
                        > ------------------------------------
                        > Posted by: Bill <bill@...>
                        > ------------------------------------
                        >
                        > To unsubscribe, send an email to:
                        > wsjtgroup-unsubscribe@yahoogroups.com
                        >
                        > WSJTGroup Homepage --> http://www.wsjtgroup.org/
                        >
                        >
                        >
                        >
                        >
                        >
                        > ------------------------------------
                        >
                        > Yahoo Groups Links
                        >
                        >
                        >
                        >
                      • Les Rayburn
                        Chen, Also interesting. Your response says that you place the HF sky noise at least 10db above the quantization noise floor of the sound card. Any idea where
                        Message 11 of 22 , Jul 17, 2014
                        • 0 Attachment
                          Chen,

                          Also interesting. Your response says that you place the HF sky noise at least 10db above the quantization noise floor of the sound card. Any idea where the VHF (144 MHz) and UHF (432 MHz) noise floor would fall in relation to the sound card?

                          Or in layman's terms, how big of a potential problem would this be on weak signal (WSJT) modes for the EME or Meteor Scatter operator? Assuming that the operator has optimized the system noise floor of the station otherwise with low noise antenna pre-amps, hardline, TXCO frequency stability, thermal control (cooling), etc. does the typical soundcard interface contribute enough noise to diminish the performance of the station?

                          Glad to hear that other hams have considered this issue in some depth. This is exactly the kind of information I was hoping for. Thank you for contributing your expertise.

                          73,

                          Les Rayburn, N1LF
                          EM63nf






                          On 7/17/2014 1:42 PM, Kok Chen wrote:
                          Hi Kai,
                          
                          I used to be intensely interested in sound cards.  I still have over a dozen of them, ranging from a cheap "$5 Amazon special" to a Presonus 24-bit codec with 117 dB of dynamic range which I used back when I was running superhet receivers. 
                          
                          (I have also posted my measurements on some of the sound cards on the RTTY Reflector in the past month or two.)
                          
                          However, after moving to HPSDR, I no longer use any sound card.  With SDRs, I am implementing modems right inside the SDR software.
                          
                          That being said, there is one point I would like to make when it comes to noise floors.
                          
                          Recall that variances ("power") of uncorrelated noise adds , not their voltages.  In the context of a sound card, there are two sets of noise... the composite analog noise of everything before the ADC (sound card, codec, call it whatever you want) and the quantization noise of the ADC itself.
                          
                          Ergo, the quantization noise of the sound card needs to be significantly below the analog noise (preamp noise, sky noise, etc) for its noise contribution to become insignificant.  If the sound card noise is at the same level as the analog noise, the output of the sound card will be 3 dB worse than an ideal sound card, and BERR thresholds are narrower than 3 dB even for steam RTTY.
                          
                          For weak signal operation, I usually place the HF sky noise at least 10 dB above the quantization noise floor of a sound card.  Notice that even with a 10 dB noise margin, the sound card is still contributing to 0.4 dB of SNR loss.
                          
                          So, keep that in mind when operating weak signal.  Make sure the sound card noise floor is much lower than the noise floor of the analog signal that you are measuring.
                          
                          Here are the noise floors (relative to full scale output) of some sound cards:
                          
                          
                          Presonus FireStudio Mobile    -117 dB
                          MicroHAM microKeyer II    -96 dB
                          Tigertronics SignaLink USB    -98 dB
                          Syba UAUD    -96 dB
                          
                          (The Syba is a "$5 Amazon special." The copy that I have is unstable when driven by a source impedance of more than 100 ohms, so be careful with some of these cheap Chinese stuff :-).
                          
                          Vy 73
                          Chen, W7AY
                          
                          
                          

                        • Jim Brown
                          ... 20 dB might be extreme, but it certainly doesn t hurt to go beyond 10 dB. The Tascam USB interfaces include a clip light, which indicates digital clip,
                          Message 12 of 22 , Jul 17, 2014
                          • 0 Attachment
                            On 7/17/2014 12:18 PM, Kok Chen wrote:
                            > I think that in those cases (assuming there is no QRM from strong signals) you might want to place the RF noise floor 20 dB or more above the sound card noise floor to reduce SNR loss even further.

                            20 dB might be extreme, but it certainly doesn't hurt to go beyond 10
                            dB. The Tascam USB interfaces include a "clip" light, which indicates
                            digital clip, and a front panel input level control. It's easy to make
                            maximum use of the dynamic range of the A/D simply by increasing the
                            input gain until the light flashes, then back off slighting until it
                            goes out. A typical 16 bit A/D in this price range will have about 90 dB
                            dynamic range. I have serious doubts that any of us will see anything
                            approaching that coming out of the audio stage in a ham RX with an
                            antenna connected that isn't coming in on the antenna. Remember -- our
                            receivers have at least one RF gain control, and at least one preamp
                            on/off switch, before the line output of the rig, which is usually what
                            we use to feed our decoders.

                            IMO, linearity of the A/D may be at least as important as the number of
                            bits.

                            73, Jim K9YC
                          • Jim Brown
                            ... Have you looked at TX phase noise with the SDRs? Published tests in EU showed some popular SDRs to have very high phase noise on TX. 73, Jim K9YC
                            Message 13 of 22 , Jul 17, 2014
                            • 0 Attachment
                              On 7/17/2014 1:34 PM, Kok Chen wrote:
                              > The LTC-2208 ADC in Hermes has an IMD3 of about -100 dBc with any carrier spacing. You can understand why my superhets (FT-1000MP, K3) have become door stops.

                              Have you looked at TX phase noise with the SDRs? Published tests in EU
                              showed some popular SDRs to have very high phase noise on TX.

                              73, Jim K9YC
                            • Bob McCormick
                              ... (snip) I will second that recommendation. It s a lot more than just an audio interface - complete rig control and even sequencing. NC1I uses the
                              Message 14 of 22 , Jul 17, 2014
                              • 0 Attachment
                                Jon W4ABC wrote:

                                > I'm using the microHam microKeyer II. You may want to give
                                > it some consideration.
                                (snip)

                                I will second that recommendation. It's a lot more than just an audio
                                interface - complete rig control and even sequencing.

                                NC1I uses the microKeyer II on both the 70cm and 23cm EME station - it's the
                                heart of the system. We also have a microKeyer SO2R+ box at the HF station
                                interfacing two rigs (and other ancillary microHAM interfaces).

                                I have one at home with my minimal setup and operate WSJT-X on HF with it.

                                Bob W1QA
                              • Arthur York
                                My Signalink USB starts oscillating at 50W, I don t think it s RF. at any rate, It still does it with a dummy load. Any suggestions? Art K0AY
                                Message 15 of 22 , Jul 19, 2014
                                • 0 Attachment
                                  My Signalink USB starts oscillating at 50W, I don't think it's RF. at any rate, It still does it with a dummy load.
                                  Any suggestions?

                                  Art
                                  K0AY
                                • chas cartmel
                                  Art Is your PC earthed to the same single point as your rig? I used this method to eliminate PC noise and may also have eliminated any RF interaction. The fact
                                  Message 16 of 22 , Jul 19, 2014
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                                    Art

                                    Is your PC earthed to the same single point as your rig?

                                    I used this method to eliminate PC noise and may also have eliminated any RF interaction. The fact that it is dependent on RF Power suggests that it is RF induced somehow.

                                     

                                    73

                                    Charlie

                                    www.G4EST.me.uk

                                     

                                    From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf Of Arthur York arthur@... [wsjtgroup]
                                    Sent: 19 July 2014 12:54
                                    To: wsjtgroup@yahoogroups.com
                                    Subject: RE: [wsjtgroup] Re: [VHF] Weak Signal Performance of Soundcard Interfaces

                                     

                                     

                                    My Signalink USB starts oscillating at 50W, I don't think it's RF. at any rate, It still does it with a dummy load.

                                    Any suggestions?

                                    Art

                                    K0AY

                                  • Jim - N4ST
                                    What band? All bands? Do you have a good earth ground on your rig? Have you tried clamp-on ferrites on the SignaLink USB cables? Do you have good connection
                                    Message 17 of 22 , Jul 19, 2014
                                    • 0 Attachment
                                      What band? All bands?
                                      Do you have a good earth ground on your rig?
                                      Have you tried clamp-on ferrites on the SignaLink USB cables?
                                      Do you have good connection between your rig and its power supply?
                                      (I had an TX distortion issue a while back caused by a loose connection on my 12V power supply)

                                      _________
                                      73 & GL,
                                      Jim - N4ST

                                      From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf Of Arthur York arthur@... [wsjtgroup]
                                      Sent: Saturday, July 19, 2014 07:54
                                      To: wsjtgroup@yahoogroups.com
                                      Subject: RE: [wsjtgroup] Re: [VHF] Weak Signal Performance of Soundcard Interfaces


                                      My Signalink USB starts oscillating at 50W, I don't think it's RF. at any rate, It still does it with a dummy load.
                                      Any suggestions?
                                      Art
                                      K0AY
                                    • chas cartmel
                                      Art I also have RF chokes on all the leads on my interface input and outputs as well as the power lead, usually several turns through clamp on ferrites. 73
                                      Message 18 of 22 , Jul 19, 2014
                                      • 0 Attachment

                                        Art

                                        I also have RF chokes on all the leads on my interface input and outputs as well as the power lead, usually several turns through clamp on ferrites.

                                         

                                        73

                                        Charlie

                                        www.G4EST.me.uk

                                         

                                        From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf Of Arthur York arthur@... [wsjtgroup]
                                        Sent: 19 July 2014 12:54
                                        To: wsjtgroup@yahoogroups.com
                                        Subject: RE: [wsjtgroup] Re: [VHF] Weak Signal Performance of Soundcard Interfaces

                                         

                                         

                                        My Signalink USB starts oscillating at 50W, I don't think it's RF. at any rate, It still does it with a dummy load.

                                        Any suggestions?

                                        Art

                                        K0AY

                                      • Jim Brown
                                        On 7/19/2014 5:36 AM, Jim - N4ST newsgroup@jimpricejr.com [wsjtgroup] ... The SignalLink USB has a Pin One Problem, which is a well known cause of hum, buzz,
                                        Message 19 of 22 , Jul 19, 2014
                                        • 0 Attachment
                                          On 7/19/2014 5:36 AM, 'Jim - N4ST' newsgroup@... [wsjtgroup]
                                          wrote:
                                          > Do you have a good earth ground on your rig?
                                          > Have you tried clamp-on ferrites on the SignaLink USB cables?
                                          > Do you have good connection between your rig and its power supply?

                                          The SignalLink USB has a Pin One Problem, which is a well known cause of
                                          hum, buzz, and RFI. The "Pin One Problem" was first understood in the
                                          pro audio world (20 years ago), which is where the name comes from --
                                          Pin One of a pro mic connector is the shield.

                                          The only proper connection of a cable shield is the shielding enclosure
                                          (usually the chassis) where it enters the enclosure). Modern gear has
                                          taken the shortcut of mounting connectors to circuit boards, but
                                          forgetting to connect the shield to the chassis. When current flows on
                                          the shield, it wanders around the PC board at the whim of the circuit
                                          board layout specialist, and eventually finds the chassis. As it
                                          wanders, it is injected into every gain stage along the way as that gain
                                          stage contacts the part of the common bus that carries that shield
                                          current. If it's RF current, it's detected and amplified. If it's power
                                          line hum or buzz, it's amplified.

                                          A connection to earth is NOT part of a cure for hum, buzz, or RFI. A
                                          connection to earth IS critical for lightning safety.

                                          The part of what we call "grounding" or "earthing" (depending on which
                                          side of the Atlantic) is what is more properly called "bonding" -- a
                                          connection from chassis to chassis of every piece of equipment in an
                                          installation with short, fat, copper. That's the first step to solving
                                          problems like this.

                                          The second part of a solution is to kill the RF current -- every
                                          conductor is an antenna, and will carry RF current from our
                                          transmitters. We may call them audio cables, or USB cables, or speaker
                                          cables, or mic cables, but Mother Nature calls them antennas. We do this
                                          with a ferrite choke whose resonance has been tweaked so that it is in
                                          the region of the RF current we want to choke. A ferrite choke is a VERY
                                          low-Q parallel resonant circuit (Q ~ 0.5 for one using the right core
                                          material), so the resonance is quite broad. A single turn choke is
                                          resonant around 150 MHz, so the resonance must be moved down to the HF
                                          spectrum by winding turns through the core. Depending on the material
                                          and the size of the core, it takes 5-7 turns to get to 20M, 12-14 to get
                                          to 80M and 160M.

                                          Below 5 MHz, Fair-Rite #31 is the weapon of choice. Above that
                                          frequency, #31 and #43 are approximately equally effective.

                                          For a lot more on this, study k9yc.com/RFI-Ham.pdf

                                          73, Jim K9YC
                                        • Joe Subich, W4TV
                                          ... The other part of this is that amateur equipment designers use unbalanced microphone connections with the mic return connected to the *shield* of the mic
                                          Message 20 of 22 , Jul 19, 2014
                                          • 0 Attachment
                                            > When current flows on the shield, it wanders around the PC board at
                                            > the whim of the circuit board layout specialist, and eventually finds
                                            > the chassis. As it wanders, it is injected into every gain stage
                                            > along the way as that gain stage contacts the part of the common bus
                                            > that carries that shield current. If it's RF current, it's detected
                                            > and amplified. If it's power line hum or buzz, it's amplified.

                                            The other part of this is that amateur equipment designers use
                                            unbalanced microphone connections with the mic return connected to the
                                            *shield* of the mic cable. The shield of the mic cable is then tied
                                            to the unbypassed emitter (or drain) of a preamplifier and the emitter
                                            connected to the circuit ground through an RF choke or high value bias
                                            resistor. This places any RF on the shield of the mic cable *in series*
                                            with the microphone audio! Unfortunately, connecting the shield of the
                                            mic cable to the chassis (as recommended by one microphone manufacturer
                                            who connects a wire from the shield to the shell of the Foster plug)
                                            will upset the preamp bias which changes gain and clip point often
                                            causing an entirely new set of problems.

                                            Designers of amateur equipment need to stop using the shield of the
                                            microphone cable for an audio return - use it for the chassis
                                            ground (PTT return) - and *bypass* the emitter/drain of their preamp
                                            circuits. Better yet, modern transceivers should be designed to use
                                            low noise op-amps with the input audio return solidly connected to the
                                            chassis/circuit common without any intervening high circuit impedance
                                            or use fully balanced high common mode rejection circuits.

                                            Not only do the designers of amateur equipment fail to handle external
                                            signal returns ("pin 1") correctly by bonding them to the chassis *at*
                                            *the connector*, they compound the problem by using circuits that are
                                            overly sensitive to unwanted signals on "pin 1".

                                            73,

                                            ... Joe, W4TV


                                            On 2014-07-19 12:30 PM, Jim Brown k9yc@... [wsjtgroup]
                                            wrote:
                                            > On 7/19/2014 5:36 AM, 'Jim - N4ST' newsgroup@... [wsjtgroup]
                                            > wrote:
                                            >> Do you have a good earth ground on your rig?
                                            >> Have you tried clamp-on ferrites on the SignaLink USB cables?
                                            >> Do you have good connection between your rig and its power supply?
                                            >
                                            > The SignalLink USB has a Pin One Problem, which is a well known cause of
                                            > hum, buzz, and RFI. The "Pin One Problem" was first understood in the
                                            > pro audio world (20 years ago), which is where the name comes from --
                                            > Pin One of a pro mic connector is the shield.
                                            >
                                            > The only proper connection of a cable shield is the shielding enclosure
                                            > (usually the chassis) where it enters the enclosure). Modern gear has
                                            > taken the shortcut of mounting connectors to circuit boards, but
                                            > forgetting to connect the shield to the chassis. When current flows on
                                            > the shield, it wanders around the PC board at the whim of the circuit
                                            > board layout specialist, and eventually finds the chassis. As it
                                            > wanders, it is injected into every gain stage along the way as that gain
                                            > stage contacts the part of the common bus that carries that shield
                                            > current. If it's RF current, it's detected and amplified. If it's power
                                            > line hum or buzz, it's amplified.
                                            >
                                            > A connection to earth is NOT part of a cure for hum, buzz, or RFI. A
                                            > connection to earth IS critical for lightning safety.
                                            >
                                            > The part of what we call "grounding" or "earthing" (depending on which
                                            > side of the Atlantic) is what is more properly called "bonding" -- a
                                            > connection from chassis to chassis of every piece of equipment in an
                                            > installation with short, fat, copper. That's the first step to solving
                                            > problems like this.
                                            >
                                            > The second part of a solution is to kill the RF current -- every
                                            > conductor is an antenna, and will carry RF current from our
                                            > transmitters. We may call them audio cables, or USB cables, or speaker
                                            > cables, or mic cables, but Mother Nature calls them antennas. We do this
                                            > with a ferrite choke whose resonance has been tweaked so that it is in
                                            > the region of the RF current we want to choke. A ferrite choke is a VERY
                                            > low-Q parallel resonant circuit (Q ~ 0.5 for one using the right core
                                            > material), so the resonance is quite broad. A single turn choke is
                                            > resonant around 150 MHz, so the resonance must be moved down to the HF
                                            > spectrum by winding turns through the core. Depending on the material
                                            > and the size of the core, it takes 5-7 turns to get to 20M, 12-14 to get
                                            > to 80M and 160M.
                                            >
                                            > Below 5 MHz, Fair-Rite #31 is the weapon of choice. Above that
                                            > frequency, #31 and #43 are approximately equally effective.
                                            >
                                            > For a lot more on this, study k9yc.com/RFI-Ham.pdf
                                            >
                                            > 73, Jim K9YC
                                            >
                                            >
                                            > ------------------------------------
                                            > Posted by: Jim Brown <k9yc@...>
                                            > ------------------------------------
                                            >
                                            > To unsubscribe, send an email to:
                                            > wsjtgroup-unsubscribe@yahoogroups.com
                                            >
                                            > WSJTGroup Homepage --> http://www.wsjtgroup.org/
                                            >
                                            >
                                            >
                                            >
                                            >
                                            >
                                            > ------------------------------------
                                            >
                                            > Yahoo Groups Links
                                            >
                                            >
                                            >
                                            >
                                          • chas cartmel
                                            Art Seems like you have the major bases covered. I have just checked around the back of my PC and have ferrites on other USB inputs such as the keyboard. These
                                            Message 21 of 22 , Jul 20, 2014
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                                              Art

                                              Seems like you have the major bases covered.

                                              I have just checked around the back of my PC and have ferrites on other USB inputs such as the keyboard.

                                               

                                              These are very much an outside chances but could RF be getting into a wireless connection (if you have one)? I choked my cable from the wall socket to the modem as well as the power lead to the modem. This reduced RFI and conversely may have reduced pick-up. Another thought is that you could be overdriving the interface although if your power control is rig based rather than input to the interface being changed then this is very unlikely.

                                              Have you played around with the volume settings from the PC and Input to the interface and interface output to the rig both volume ‘sent’ and any internal volume controls?

                                               

                                              Hope you get it sorted soon. These issues really bug but you get a great sense of satisfaction when they get solved.

                                               

                                              73

                                              Charlie

                                              www.G4EST.me.uk

                                               

                                              From: Arthur York [mailto:arthur@...]
                                              Sent: 19 July 2014 15:06
                                              To: chas cartmel
                                              Subject: Re: [wsjtgroup] Weak Signal Performance of Soundcard Interfaces

                                               



                                              On Saturday, July 19, 2014, chas cartmel <chas@...> wrote:

                                              Art

                                              I also have RF chokes on all the leads on my interface input and outputs as well as the power lead, usually several turns through clamp on ferrites.

                                               

                                              73

                                              Charlie

                                              www.G4EST.me.uk

                                               

                                              From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf Of Arthur York arthur@... [wsjtgroup]
                                              Sent: 19 July 2014 12:54
                                              To: wsjtgroup@yahoogroups.com
                                              Subject: RE: [wsjtgroup] Re: [VHF] Weak Signal Performance of Soundcard Interfaces

                                               

                                              Yes I have a common ground in my shack.  I have 8 ferite chokes on the obvious susects.

                                               

                                               

                                               

                                              My Signalink USB starts oscillating at 50W, I don't think it's RF. at any rate, It still does it with a dummy load.

                                              Any suggestions?

                                              Art

                                              K0AY

                                            • chas cartmel
                                              Great news. See you on the air i hope 73 Charlie www.G4EST.me.uk From: Arthur York [mailto:arthur@yorkfamily.net] Sent: 20 July 2014 11:02 To: chas cartmel
                                              Message 22 of 22 , Jul 21, 2014
                                              • 0 Attachment

                                                Great news.

                                                 

                                                See you on the air i hope

                                                 

                                                73

                                                Charlie

                                                www.G4EST.me.uk

                                                 

                                                From: Arthur York [mailto:arthur@...]
                                                Sent: 20 July 2014 11:02
                                                To: chas cartmel
                                                Subject: Re: [wsjtgroup] Weak Signal Performance of Soundcard Interfaces

                                                 

                                                Charles...

                                                I tore it all apart and put it back together again.  It's working!  Many thanks for all your suggestions.

                                                Art

                                                K0AY

                                                 

                                                On Sun, Jul 20, 2014 at 4:05 AM, chas cartmel <chas@...> wrote:

                                                Art

                                                Seems like you have the major bases covered.

                                                I have just checked around the back of my PC and have ferrites on other USB inputs such as the keyboard.

                                                 

                                                These are very much an outside chances but could RF be getting into a wireless connection (if you have one)? I choked my cable from the wall socket to the modem as well as the power lead to the modem. This reduced RFI and conversely may have reduced pick-up. Another thought is that you could be overdriving the interface although if your power control is rig based rather than input to the interface being changed then this is very unlikely.

                                                Have you played around with the volume settings from the PC and Input to the interface and interface output to the rig both volume ‘sent’ and any internal volume controls?

                                                 

                                                Hope you get it sorted soon. These issues really bug but you get a great sense of satisfaction when they get solved.

                                                 

                                                73

                                                Charlie

                                                www.G4EST.me.uk

                                                 

                                                From: Arthur York [mailto:arthur@...]
                                                Sent: 19 July 2014 15:06
                                                To: chas cartmel
                                                Subject: Re: [wsjtgroup] Weak Signal Performance of Soundcard Interfaces

                                                 



                                                On Saturday, July 19, 2014, chas cartmel <chas@...> wrote:

                                                Art

                                                I also have RF chokes on all the leads on my interface input and outputs as well as the power lead, usually several turns through clamp on ferrites.

                                                 

                                                73

                                                Charlie

                                                www.G4EST.me.uk

                                                 

                                                From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf Of Arthur York arthur@... [wsjtgroup]
                                                Sent: 19 July 2014 12:54
                                                To: wsjtgroup@yahoogroups.com
                                                Subject: RE: [wsjtgroup] Re: [VHF] Weak Signal Performance of Soundcard Interfaces

                                                 

                                                Yes I have a common ground in my shack.  I have 8 ferite chokes on the obvious susects.

                                                 

                                                 

                                                 

                                                My Signalink USB starts oscillating at 50W, I don't think it's RF. at any rate, It still does it with a dummy load.

                                                Any suggestions?

                                                Art

                                                K0AY

                                                 

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