Loading ...
Sorry, an error occurred while loading the content.

Dual JFET Preamp?

Expand Messages
  • cqer01
    Does anyone in the group have experience with this product: https://www.sv1afn.com/j310preamp.html It looks to be very well constructed and suitable for a loop
    Message 1 of 8 , Jan 3, 2014
    • 0 Attachment
      Does anyone in the group have experience with this product:


      https://www.sv1afn.com/j310preamp.html

      It looks to be very well constructed and suitable for a loop preamp.

      Steve / VE7SL

    • Gary Smith
      Looks really interesting.  Might just order it and try it with my FSL just for fun.  I already have an 18 db preamp that works very well, but I always like
      Message 2 of 8 , Jan 3, 2014
      • 0 Attachment
        Looks really interesting.  Might just order it and try it with my FSL just for fun.  I already have an 18 db preamp that works very well, but I always like to play with stuff.

        Gary
        WA1TJB


        On Friday, January 3, 2014 6:15 PM, "ve7sl@..." <ve7sl@...> wrote:
         
        Does anyone in the group have experience with this product:

        https://www.sv1afn.com/j310preamp.html

        It looks to be very well constructed and suitable for a loop preamp.

        Steve / VE7SL



      • Gary Smith
        Does anyone know where I can get the adapter from sma connector to a BNC? Gary WA1TJB On Friday, January 3, 2014 7:21 PM, Gary Smith wrote:
        Message 3 of 8 , Jan 3, 2014
        • 0 Attachment
          Does anyone know where I can get the adapter from sma connector to a BNC?

          Gary
          WA1TJB


          On Friday, January 3, 2014 7:21 PM, Gary Smith <wa1tjb@...> wrote:
          Looks really interesting.  Might just order it and try it with my FSL just for fun.  I already have an 18 db preamp that works very well, but I always like to play with stuff.

          Gary
          WA1TJB


          On Friday, January 3, 2014 6:15 PM, "ve7sl@..." <ve7sl@...> wrote:
           
          Does anyone in the group have experience with this product:

          https://www.sv1afn.com/j310preamp.html

          It looks to be very well constructed and suitable for a loop preamp.

          Steve / VE7SL





        • davelimmer@rocketmail.com
          Hi Steve, I used a version of this circuit many years ago as a relay-switched preamp for a homebrew communications receiver, and it worked extremely well ahead
          Message 4 of 8 , Jan 4, 2014
          • 0 Attachment
            Hi Steve,

            I used a version of this circuit many years ago as a relay-switched preamp for a homebrew communications receiver, and it worked extremely well ahead of an SBL-1 mixer.

            It's essentially cribbed from the "Omega"  HF transceiver design by G3WPO and G4JST, which was published in the UK in the mid-80s in the now defunct "Ham Radio Today" magazine. It might be nice if SV1AFN acknowledged this sometime...

            A nice design, though, and the SMD implementation is very neat.

            Regards,

            Dave
          • Steve
            ... dozens on e-bay and with free-shipping to boot! Steve WEB - The VE7SL Radio Notebook : http://members.shaw.ca/ve7sl
            Message 5 of 8 , Jan 4, 2014
            • 0 Attachment
              >Does anyone know where I can get the adapter from sma connector to a BNC?



              dozens on e-bay and with free-shipping to boot!

              Steve



              WEB - "The VE7SL Radio Notebook": http://members.shaw.ca/ve7sl
            • Steve
              Thanks info Dave....I was not aware of the history. Steve / 73 ... WEB - The VE7SL Radio Notebook : http://members.shaw.ca/ve7sl
              Message 6 of 8 , Jan 4, 2014
              • 0 Attachment
                Thanks info Dave....I was not aware of the history.

                Steve / 73


                > Hi Steve,
                >
                > I used a version of this circuit many years ago as a relay-switched preamp
                > for a homebrew communications receiver, and it worked extremely well ahead
                > of an SBL-1 mixer.
                >
                > It's essentially cribbed from the "Omega" HF transceiver design by G3WPO
                > and G4JST, which was published in the UK in the mid-80s in the now defunct
                > "Ham Radio Today" magazine. It might be nice if SV1AFN acknowledged this
                > sometime...
                >
                > A nice design, though, and the SMD implementation is very neat.
                >
                > Regards,
                >
                > Dave


                WEB - "The VE7SL Radio Notebook": http://members.shaw.ca/ve7sl
              • vbifyz
                The website doesn t mention the input impedance of the amplifier, but it looks like it is fairly high. This is not optimal for the loop, which works better
                Message 7 of 8 , Jan 6, 2014
                • 0 Attachment
                  The website doesn't mention the input impedance of the amplifier, but it looks like it is fairly high. This is not optimal for the loop, which works better when loaded with a low impedance.
                  You can read excellent articles by Chris N7ZWY in the files section of this group to learn more about loop preamps.
                  This amplifier may be more suitable for a short whip.

                  73, Mike
                • Chris Trask
                  ... Yes, it s more suitable for short whip (monopole) antennas that require a high input impedance amplifier. Loops have a very low terminal impedance, so a
                  Message 8 of 8 , Jan 7, 2014
                  • 0 Attachment
                    >
                    >The website doesn't mention the input impedance of the amplifier, but it looks like it is fairly high. This
                    >is not optimal for the loop, which works better when loaded with a low impedance.
                    >You can read excellent articles by Chris N7ZWY in the files section of this group to learn more about loop
                    >preamps.
                    >This amplifier may be more suitable for a short whip.
                    >

                    Yes, it's more suitable for short whip (monopole) antennas that require a high input impedance amplifier. Loops have a very low terminal impedance, so a balanced common-base amplifier is more suitable. I have a fairly rigorous one in the files section, and a simpler one was mentioned here recently.


                    Chris Trask
                    N7ZWY / WDX3HLB
                    Senior Member IEEE
                    http://www.home.earthlink.net/~christrask/
                  Your message has been successfully submitted and would be delivered to recipients shortly.