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

Re: 10W Linear amp from Kits & Parts. Anyone tried it with SR yet?

Expand Messages
  • Mike Collins
    ... about. ... better. Hi Guys and Happy New Year, The Softrock driver and PA stage is kind of average for IMD. I like the IMD performace with the Mits RD
    Message 1 of 22 , Dec 30, 2008
      > If you see in the files section there is a measured ~28dBc IMD from
      > the SR PA. Compare that to the measurements on the PLB-15 document
      > (-48dBc to -66dBc)and I hope that you understand what I am talking
      about.
      > In my case, I could not reach even the acclaimed -28dBc of the SR PA,
      > I had more like -20dBc but that might be due to local problems.
      > Either way the difference (-28dBc to -48dBc) is quite large, so I
      > decided to scrap the SR PA and stay with the KT610/RD16HHF1 combo
      > where the IMD to Watts ratio is something that (IMHO) I find much
      better.

      Hi Guys and Happy New Year,

      The Softrock driver and PA stage is kind of average for IMD. I like
      the IMD performace with the Mits RD parts too.

      One thing to put in perspective is that in the last several years, the
      ARRL lab testing has reported TX 3rd order IMD levels from -21dBPEP to
      -35dBPEP for the "top" commercial rigs. Even the highly desired
      Elecraft K3 is reported at -27dBPEP, and the ICOM 7700 is -28dBPEP.
      These are dBPEP numbers which are 6dB "better" than comparing to each
      tone level. So if you don't like the Softrock TX IMD performance, you
      better not XMIT with your commercial rig!!

      73, Mike Collins KF4BQ
    • cesco12342000
      ... What does the 100mw refer to? Average or PEP ? If it s average that is what i would expect from a 1W PA. Drm has quite a crest factor. With 100mw average
      Message 2 of 22 , Dec 30, 2008
        > I have used it on 7MHz for test DRM transmissions, and could
        > only get just under 100mW with acceptable IPs (> -30dB)

        What does the 100mw refer to? Average or PEP ?

        If it's average that is what i would expect from a 1W PA. Drm has
        quite a crest factor. With 100mw average there will be pep values in
        excess of 1W (clipping).
      • Mark GM4ISM
        Hi, the value obtained was actually about 70mw mean power, measured on a modern spectrum analyser with an occupied channel power function Many simple diode
        Message 3 of 22 , Dec 30, 2008
          Hi, the value obtained was actually about 70mw mean power, measured on a modern spectrum analyser with an occupied channel power function
          Many simple diode detectors respond inaccurately to OFDM signals, although thermal power meters are OK.
          peak to mean ratio is nominally assumed to be 10dB for multi-carrier  OFDM type signals.  With good precorrection one can obtain good IPs with about 6dB headroom on the amplifier, but I don't have any precorrection available with Spark.
          30dB is a rather minimal figure, as a driver be it for SSB or DRM.
          I know a lot of commercial rigs are equally poor at the output of the final, and you sure can tell on the air with some stations :<)
          My point is that I find the level of IPs at 1w output from the softrock poorer than I am comfortable with when driving an amplifier. IPs don't usually get better if you add another stage.
          I would much rather under-run a stage and get good IMD than rely on the max power from each stage as the minimum drive requirement for the next.
          Of course with SDR, some clever person could build in precorrection routines :<)  please?
          mark GM4ISM
           
           
           
           
           
           
          ----- Original Message -----
          Sent: Tuesday, December 30, 2008 8:41 PM
          Subject: [softrock40] Re: 10W Linear amp from Kits & Parts. Anyone tried it with SR yet?

          > I have used it on 7MHz for test DRM transmissions, and could
          > only get just under 100mW with acceptable IPs (> -30dB)

          What does the 100mw refer to? Average or PEP ?

          If it's average that is what i would expect from a 1W PA. Drm has
          quite a crest factor. With 100mw average there will be pep values in
          excess of 1W (clipping).



          No virus found in this incoming message.
          Checked by AVG - http://www.avg.com
          Version: 8.0.176 / Virus Database: 270.10.1/1869 - Release Date: 12/30/2008 12:06 PM
        • Christos Nikolaou
          Hi Mike, I agree that the commercial rigs have these figures. One thing though needs to be noted, the ARRL numbers refer to full power eg 100W whereas here we
          Message 4 of 22 , Dec 30, 2008
            Hi Mike,

            I agree that the commercial rigs have these figures.
            One thing though needs to be noted, the ARRL numbers refer to full
            power eg 100W whereas here we have 100mW-1W. :-)

            73,
            Christos SV1EIA

            --- In softrock40@yahoogroups.com, "Mike Collins" <mikecol@...> wrote:
            >
            > > If you see in the files section there is a measured ~28dBc IMD from
            > > the SR PA. Compare that to the measurements on the PLB-15 document
            > > (-48dBc to -66dBc)and I hope that you understand what I am talking
            > about.
            > > In my case, I could not reach even the acclaimed -28dBc of the SR PA,
            > > I had more like -20dBc but that might be due to local problems.
            > > Either way the difference (-28dBc to -48dBc) is quite large, so I
            > > decided to scrap the SR PA and stay with the KT610/RD16HHF1 combo
            > > where the IMD to Watts ratio is something that (IMHO) I find much
            > better.
            >
            > Hi Guys and Happy New Year,
            >
            > The Softrock driver and PA stage is kind of average for IMD. I like
            > the IMD performace with the Mits RD parts too.
            >
            > One thing to put in perspective is that in the last several years, the
            > ARRL lab testing has reported TX 3rd order IMD levels from -21dBPEP to
            > -35dBPEP for the "top" commercial rigs. Even the highly desired
            > Elecraft K3 is reported at -27dBPEP, and the ICOM 7700 is -28dBPEP.
            > These are dBPEP numbers which are 6dB "better" than comparing to each
            > tone level. So if you don't like the Softrock TX IMD performance, you
            > better not XMIT with your commercial rig!!
            >
            > 73, Mike Collins KF4BQ
            >
          • sivan_toledo
            Christos, how do you connect the output of the QSE to the PLB-15 ampifier? Do you use the tuned transformer of the SR between them? Thanks, Sivan
            Message 5 of 22 , Dec 31, 2008
              Christos, how do you connect the output of the QSE to the PLB-15
              ampifier? Do you use the tuned transformer of the SR between them?

              Thanks, Sivan

              --- In softrock40@yahoogroups.com, "Christos Nikolaou" <sv1eia@...> wrote:
              >
              > I've measured the IMD from softrock PA and it is not even near the IMD
              > performance of the driver stage from the PLB-15 (KT610: -50dBc) so I
              > do not use the SR PA any more, I take direct output from the QSE and
              > everything is fine.
              > If you put attenuators, then you will just enhance the bad IMD
              > performance of the SR PA.
              >
              > ...
            • dick_faust
              ... Here is another 20W option based upon the G6ALU design for Pic-A-Star http://hpsdr.org/pennywhistle.html More info at the wiki
              Message 6 of 22 , Dec 31, 2008
                --- In softrock40@yahoogroups.com, "drmail377" <drmail377@...> wrote:
                >
                > At:
                >
                > http://kitsandparts.com/linearamp.php
                >
                > There's a 10W HF linear (CW/SSB) amplifier kit that looks like it will
                > drive with +1dBm. A 5W kit is coming out in January 2009. There are
                > LPF and BPF kits available on the site as well.
                >
                > Has anyone tried one of these with a Softrock radio yet?
                >
                > 73's David
                >
                Here is another 20W option based upon the G6ALU design for Pic-A-Star
                http://hpsdr.org/pennywhistle.html
                More info at the wiki
                http://hpsdr.org/wiki/index.php?title=PENNYWHISTLE
                Dick K9IVB
              • Christos Nikolaou
                Hi Sivan, From the secondary winding of the QSE transformer get it with a .1uF blocking capacitor. In my case I ve also removed the provided transformer and
                Message 7 of 22 , Dec 31, 2008
                  Hi Sivan,

                  From the secondary winding of the QSE transformer get it with a .1uF
                  blocking capacitor.

                  In my case I've also removed the provided transformer and placed a
                  broadband MiniCircuits one in both Rx and Tx. You do not need to do
                  that if you plan to have only the band that the SR is designed to.

                  Best wishes for a Happy New Year
                  Christos SV1EIA



                  --- In softrock40@yahoogroups.com, "sivan_toledo" <sivan.toledo@...>
                  wrote:
                  >
                  > Christos, how do you connect the output of the QSE to the PLB-15
                  > ampifier? Do you use the tuned transformer of the SR between them?
                  >
                  > Thanks, Sivan
                  >
                  > --- In softrock40@yahoogroups.com, "Christos Nikolaou" <sv1eia@> wrote:
                  > >
                  > > I've measured the IMD from softrock PA and it is not even near the IMD
                  > > performance of the driver stage from the PLB-15 (KT610: -50dBc) so I
                  > > do not use the SR PA any more, I take direct output from the QSE and
                  > > everything is fine.
                  > > If you put attenuators, then you will just enhance the bad IMD
                  > > performance of the SR PA.
                  > >
                  > > ...
                  >
                • sivan_toledo
                  Thanks, that s exactly what I wanted to know. I wanted to try something like this out but was wondering whether the tuned transformer was serving some
                  Message 8 of 22 , Jan 1, 2009
                    Thanks, that's exactly what I wanted to know. I wanted to try
                    something like this out but was wondering whether the tuned
                    transformer was serving some necessary filtering function between the
                    mixer and the driver and PA. From your reply I understand that a
                    broadband path all the way from the mixer to the output LPF should
                    work fine.

                    Happy New Year, Sivan

                    --- In softrock40@yahoogroups.com, "Christos Nikolaou" <sv1eia@...> wrote:
                    >
                    > Hi Sivan,
                    >
                    > From the secondary winding of the QSE transformer get it with a .1uF
                    > blocking capacitor.
                    >
                    > In my case I've also removed the provided transformer and placed a
                    > broadband MiniCircuits one in both Rx and Tx. You do not need to do
                    > that if you plan to have only the band that the SR is designed to.
                    >
                    > Best wishes for a Happy New Year
                    > Christos SV1EIA
                    >
                    >
                    >
                    > --- In softrock40@yahoogroups.com, "sivan_toledo" <sivan.toledo@>
                    > wrote:
                    > >
                    > > Christos, how do you connect the output of the QSE to the PLB-15
                    > > ampifier? Do you use the tuned transformer of the SR between them?
                    > >
                    > > Thanks, Sivan
                    > >
                    > > --- In softrock40@yahoogroups.com, "Christos Nikolaou" <sv1eia@>
                    wrote:
                    > > >
                    > > > I've measured the IMD from softrock PA and it is not even near
                    the IMD
                    > > > performance of the driver stage from the PLB-15 (KT610: -50dBc)
                    so I
                    > > > do not use the SR PA any more, I take direct output from the QSE and
                    > > > everything is fine.
                    > > > If you put attenuators, then you will just enhance the bad IMD
                    > > > performance of the SR PA.
                    > > >
                    > > > ...
                    > >
                    >
                  • M0FMT
                    Hi Christos (SV1EIA)   Tnx for the idea. Could you publish details like PN for the xformer etc?   Many thanks and Happy New Year to you and all on list and
                    Message 9 of 22 , Jan 1, 2009
                      Hi Christos (SV1EIA)
                       
                      Tnx for the idea. Could you publish details like PN for the xformer etc?
                       
                      Many thanks and Happy New Year to you and all on list and Tony of course.
                       
                      73 petefmt
                       
                       

                    • Christos Nikolaou
                      This is used already in SDR-1000 in the QSE/QSD so it is a proven one http://www.minicircuits.com/pdfs/T4-1.pdf ... etc? ... course.
                      Message 10 of 22 , Jan 1, 2009
                        This is used already in SDR-1000 in the QSE/QSD so it is a proven one

                        http://www.minicircuits.com/pdfs/T4-1.pdf



                        --- In softrock40@yahoogroups.com, M0FMT <m0fmt@...> wrote:
                        >
                        > Hi Christos (SV1EIA)
                        >  
                        > Tnx for the idea. Could you publish details like PN for the xformer
                        etc?
                        >  
                        > Many thanks and Happy New Year to you and all on list and Tony of
                        course.
                        >  
                        > 73 petefmt
                        >  
                        >  
                        >
                      Your message has been successfully submitted and would be delivered to recipients shortly.