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

Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...

Expand Messages
  • Tom
    Hi Chris, Don t know if you got any answers on this, but I will offer my opinion. The ultimate commercially manufactured production amplifier for the SoftRock
    Message 1 of 19 , Nov 15, 2012
    • 0 Attachment
      Hi Chris,
      Don't know if you got any answers on this, but I will offer my opinion.
      The ultimate commercially manufactured production amplifier for the SoftRock is the EF Johnson Desk Kilowatt. Running a pair of 4-400's, it only requires 2 - 3 watts drive on SSB to provide 1000 watts input in a single stage of amplification. I believe this is a conservative rating. Unfortunately, only 402 were made between 1955 and 1964. In 1958, the cost was a mere $1595 (transmitter pedestal only) and another $132 for the actual desk. The pedestal alone weighs 400 pounds. If you can find one for sale, shipping might be prohibitive to the UK. Nice ones sell for $3000 - $3500.
      It does not make the best mobile amplifier, however, as it would require mounting in the back of a pickup truck and pulling a fairly stout engine generator behind. :-)
      Mine is currently undergoing a complete ground up restoration, so I am not able to actually test this combination at the moment. I would not seriously recommend even trying it into anything other than a dummy load without adding some seriously good output filtering between the RXTX and the Desk, and even then......well I guess I'd like to see what it looks like on a spectrum analyzer first.
      With one of these, when you aren't running a KW or more on CW or SSB, you can make friends and influence people with a KW on AM :-)
      I'm guessing in the UK, that might get you noticed.
      73, Tom NØBS

      --- In softrock40@yahoogroups.com, Chris Wilson <chris@...> wrote:
      >
      >
      >
      > 11/11/2012 20:12
      >
      > Purely out of idle curiosity what's the most power anyone has run SSB
      > from a Softrock RXTX at, via a linear? How did they stage things from
      > a half watt or whatever to their final figure? Thanks.
      >
      > --
      > Best Regards,
      > Chris Wilson. 2E0ILY
      > mailto: chris@...
      >
    • Alan
      ... Subject: [softrock40] Re: What s the most TX power anyone has amplified an RXTX to? Just out of curiosity... Another related question may be What is the
      Message 2 of 19 , Nov 15, 2012
      • 0 Attachment
        ----- Original Message -----
        Subject: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...

        Another related question may be "What is the largest spurious signal transmitted from a Softrock, (or other SDR)."

        On WSPR "Chat" the other day I came across someone who was transmitting without having checked his TX IQ was correct. Transmitting
        on the wrong frequency.
        He also knew nothing about setting TX IQ balance so when the IQ was set correctly his image may have been only 25dB down.
        If he had a fault he could have been transmitting simultaneously on both frequencies without knowing. The same as "mirrored"
        receiving.

        A good understanding of what is involved is necessary before amplifying mistakes. Any soundcard SDR transmitter needs careful
        setting by someone who at least understands the basics. A receiver must be used to check.

        I sometimes wonder when immediately after building a Softrock somebody says "I want more power". It took me quite a while to get a
        fair understanding of the Softrock and software.

        73 Alan G4ZFQ
      • Chris Wilson
        ... 16/11/2012 14:36 As I said, I was just curious as to how much power people realistically run from these things, and my thoughts were whether they could be
        Message 3 of 19 , Nov 16, 2012
        • 0 Attachment
          >

          > ----- Original Message -----
          > Subject: [softrock40] Re: What's the most TX power anyone has
          > amplified an RXTX to? Just out of curiosity...

          > Another related question may be "What is the largest spurious
          > signal transmitted from a Softrock, (or other SDR)."

          > On WSPR "Chat" the other day I came across someone who was
          > transmitting without having checked his TX IQ was correct. Transmitting
          > on the wrong frequency.
          > He also knew nothing about setting TX IQ balance so when the IQ was
          > set correctly his image may have been only 25dB down.
          > If he had a fault he could have been transmitting simultaneously on
          > both frequencies without knowing. The same as "mirrored"
          > receiving.

          > A good understanding of what is involved is necessary before
          > amplifying mistakes. Any soundcard SDR transmitter needs careful
          > setting by someone who at least understands the basics. A receiver must be used to check.

          > I sometimes wonder when immediately after building a Softrock
          > somebody says "I want more power". It took me quite a while to get a
          > fair understanding of the Softrock and software.

          > 73 Alan G4ZFQ




          16/11/2012 14:36

          As I said, I was just curious as to how much power people
          realistically run from these things, and my thoughts were whether they
          could be made clean enough to be unobtrusive at high power output
          levels, or whether the fact the majority are QRP tends to hide any
          nasties from the fellow spectrum users. Is a soundcard based SDR TX
          bound to be dirtier than a good conventional transmitter? Or can the
          Softrock RXTX package be amplified to serious levels without becoming
          unsociable, and without major doctoring?

          --
          Best Regards,
          Chris Wilson. 2E0ILY
        • MIKE DURKIN
          I want more power .... ~50-100mW from my UHFSDR is abit low.... exspecily into 100 of RG8x ... Mike KC7NOA To: softrock40@yahoogroups.com From:
          Message 4 of 19 , Nov 16, 2012
          • 0 Attachment
            I want more power .... ~50-100mW from my UHFSDR is abit low.... exspecily into 100' of RG8x ...

            Mike KC7NOA


            To: softrock40@yahoogroups.com
            From: alan4alan@...
            Date: Fri, 16 Nov 2012 06:55:02 +0000
            Subject: Re: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...

             

            ----- Original Message -----
            Subject: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...

            Another related question may be "What is the largest spurious signal transmitted from a Softrock, (or other SDR)."

            On WSPR "Chat" the other day I came across someone who was transmitting without having checked his TX IQ was correct. Transmitting
            on the wrong frequency.
            He also knew nothing about setting TX IQ balance so when the IQ was set correctly his image may have been only 25dB down.
            If he had a fault he could have been transmitting simultaneously on both frequencies without knowing. The same as "mirrored"
            receiving.

            A good understanding of what is involved is necessary before amplifying mistakes. Any soundcard SDR transmitter needs careful
            setting by someone who at least understands the basics. A receiver must be used to check.

            I sometimes wonder when immediately after building a Softrock somebody says "I want more power". It took me quite a while to get a
            fair understanding of the Softrock and software.

            73 Alan G4ZFQ


          • kk4dcf
            Alan, was that me? KK4DCF. I think it was and didn t realize that was you on the chat there. I m completely new to this so there are quite a few unknown
            Message 5 of 19 , Nov 16, 2012
            • 0 Attachment
              Alan, was that me? KK4DCF. I think it was and didn't realize that was you on the chat there.

              I'm completely new to this so there are quite a few "unknown unknowns" to get through. You can rest easy though, I think I'm done trying to get on the air.

              James.

              --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
              >
              >
              > ----- Original Message -----
              > Subject: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...
              >
              > Another related question may be "What is the largest spurious signal transmitted from a Softrock, (or other SDR)."
              >
              > On WSPR "Chat" the other day I came across someone who was transmitting without having checked his TX IQ was correct. Transmitting
              > on the wrong frequency.
              > He also knew nothing about setting TX IQ balance so when the IQ was set correctly his image may have been only 25dB down.
              > If he had a fault he could have been transmitting simultaneously on both frequencies without knowing. The same as "mirrored"
              > receiving.
              >
              > A good understanding of what is involved is necessary before amplifying mistakes. Any soundcard SDR transmitter needs careful
              > setting by someone who at least understands the basics. A receiver must be used to check.
              >
              > I sometimes wonder when immediately after building a Softrock somebody says "I want more power". It took me quite a while to get a
              > fair understanding of the Softrock and software.
              >
              > 73 Alan G4ZFQ
              >
            • Sid Boyce
              ... I know people are using the SDR-CUBE (a SR v6.3 with smarts) with 50W and more. http://sdrbuzz.com/forum/archive/index.php?t-42.html 73 ... Sid. -- Sid
              Message 6 of 19 , Nov 16, 2012
              • 0 Attachment
                On 16/11/12 14:40, Chris Wilson wrote:
                >
                >>
                >> ----- Original Message -----
                >> Subject: [softrock40] Re: What's the most TX power anyone has
                >> amplified an RXTX to? Just out of curiosity...
                >> Another related question may be "What is the largest spurious
                >> signal transmitted from a Softrock, (or other SDR)."
                >> On WSPR "Chat" the other day I came across someone who was
                >> transmitting without having checked his TX IQ was correct. Transmitting
                >> on the wrong frequency.
                >> He also knew nothing about setting TX IQ balance so when the IQ was
                >> set correctly his image may have been only 25dB down.
                >> If he had a fault he could have been transmitting simultaneously on
                >> both frequencies without knowing. The same as "mirrored"
                >> receiving.
                >> A good understanding of what is involved is necessary before
                >> amplifying mistakes. Any soundcard SDR transmitter needs careful
                >> setting by someone who at least understands the basics. A receiver must be used to check.
                >> I sometimes wonder when immediately after building a Softrock
                >> somebody says "I want more power". It took me quite a while to get a
                >> fair understanding of the Softrock and software.
                >> 73 Alan G4ZFQ
                >
                >
                >
                > 16/11/2012 14:36
                >
                > As I said, I was just curious as to how much power people
                > realistically run from these things, and my thoughts were whether they
                > could be made clean enough to be unobtrusive at high power output
                > levels, or whether the fact the majority are QRP tends to hide any
                > nasties from the fellow spectrum users. Is a soundcard based SDR TX
                > bound to be dirtier than a good conventional transmitter? Or can the
                > Softrock RXTX package be amplified to serious levels without becoming
                > unsociable, and without major doctoring?
                >
                I know people are using the SDR-CUBE (a SR v6.3 with smarts) with 50W
                and more.
                http://sdrbuzz.com/forum/archive/index.php?t-42.html
                73 ... Sid.

                --
                Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
                Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
                Senior Staff Specialist, Cricket Coach
                Microsoft Windows Free Zone - Linux used for all Computing Tasks
              • John Greusel
                James, Don t give up on going on the air. Slow down a little and read the literature. The IQ signal is somewhat like setting the front to back and left to
                Message 7 of 19 , Nov 16, 2012
                • 0 Attachment
                  James,

                  Don't give up on going on the air.
                  Slow down a little and read the literature.
                  The IQ signal is somewhat like setting the front to back and left to right balance on your car sound system.
                  You don't want the left channel on the right and you don't want it all in the back or all on one side or the other.
                  If it's not set properly you emphasize an "image" that not supposed to be there and diminish the actual signal.
                  Additionally, you can reverse USB and LSB and be at the wrong frequency. As Alan said- you need to check this with another receiver.
                  Read the Flex documents for IQ balancing (particularly related to the Flex 1000) and that will help you understand.

                  John
                  KC9OJV


                   



                  From: kk4dcf <oohay@...>
                  To: softrock40@yahoogroups.com
                  Sent: Friday, November 16, 2012 9:42 AM
                  Subject: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...

                   
                  Alan, was that me? KK4DCF. I think it was and didn't realize that was you on the chat there.

                  I'm completely new to this so there are quite a few "unknown unknowns" to get through. You can rest easy though, I think I'm done trying to get on the air.

                  James.

                  --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
                  >
                  >
                  > ----- Original Message -----
                  > Subject: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...
                  >
                  > Another related question may be "What is the largest spurious signal transmitted from a Softrock, (or other SDR)."
                  >
                  > On WSPR "Chat" the other day I came across someone who was transmitting without having checked his TX IQ was correct. Transmitting
                  > on the wrong frequency.
                  > He also knew nothing about setting TX IQ balance so when the IQ was set correctly his image may have been only 25dB down.
                  > If he had a fault he could have been transmitting simultaneously on both frequencies without knowing. The same as "mirrored"
                  > receiving.
                  >
                  > A good understanding of what is involved is necessary before amplifying mistakes. Any soundcard SDR transmitter needs careful
                  > setting by someone who at least understands the basics. A receiver must be used to check.
                  >
                  > I sometimes wonder when immediately after building a Softrock somebody says "I want more power". It took me quite a while to get a
                  > fair understanding of the Softrock and software.
                  >
                  > 73 Alan G4ZFQ
                  >



                • Alan
                  ... Subject: [softrock40] Re: What s the most TX power anyone has amplified an RXTX to? Just out of curiosity... ... James, Maybe, but only if you admit it:)
                  Message 8 of 19 , Nov 16, 2012
                  • 0 Attachment
                    ----- Original Message -----
                    Subject: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...


                    > Alan, was that me? KK4DCF. I think it was and didn't realize that was you on the chat there.

                    James,

                    Maybe, but only if you admit it:) WSPR chat scrolls off the bottom, as far as I know it gets lost. So I thought I could mention that
                    without accusing anybody in particular.
                    Don't stop trying, learn what to do. WSPR is good for QRP. Given good conditions 1 watt will reach everywhere on 40m and above. And
                    much less may be used successfully.

                    Chris,

                    The US spurious regulations seem fairly harsh, they seem to make no allowance for QRP.
                    There are some who say that the only way to be sure to keep within US regulations is to use PSDR, which shifts the TX frequency so
                    that the centre frequency is at the supressed carrier point. This way the image looks like badly supressed sideband and any LO
                    leakage looks like bad carrier supression.
                    Other countries seem to have similar regulations.

                    Our guidelines in the UK seem a bit less demanding and using low power I think we may be a little more relaxed.
                    But even so, it is good to get an understanding of TX image supression and LO leakage. And as with any transmitter, the effects of
                    overdriving.
                    Now, once we start amplifying this does become more important. As I say some suggest that the PSDR system is the only way to get a
                    signal that is within regulations, altough the actual emissions are the same. They are merely on different frequencies and
                    classified differently.

                    I really do not know how something like a Softrock compares with other amateur gear. I presume when it is setup properly it will
                    pass. There is a lot of fully commercial gear out there that is horribly misused but we should not join them.
                    I'm just saying that a simple SDR needs a little more understanding, it's not plug and play!

                    73 Alan G4ZFQ
                  • kk4dcf
                    ... I m certain it was me. The issue was that I built the kit with TX jumpers crossed and RX jumpers straight for PSDR and then started using linux instead. I
                    Message 9 of 19 , Nov 16, 2012
                    • 0 Attachment
                      >
                      > Maybe, but only if you admit it:) WSPR chat scrolls off the bottom, as far as I know it gets lost. So I thought I could mention that
                      > without accusing anybody in particular.
                      > Don't stop trying, learn what to do. WSPR is good for QRP. Given good conditions 1 watt will reach everywhere on 40m and above. And
                      > much less may be used successfully.
                      >

                      I'm certain it was me. The issue was that I built the kit with TX jumpers crossed and RX jumpers straight for PSDR and then started using linux instead. I forgot I had done that.

                      That mistake points out to me that I do not have the equipment needed to do this. Especially the most basic testing gear, another receiver.

                      The other major issue is that I don't have a viable home antenna. I've tried a handful of configurations and while I seem to be able to transmit decently (per WSPR and the 1 QSO I've had in the past week) the receive performance is terrible (also per WSPR and the 1 QSO). I expect to setup portable in a good open space next week to try and confirm my issues are antenna related. If that truly is the case then I'm probably just going to sell this all off and try again with a commercial rig in a few years when I move.

                      James.
                    • Parks, Tony
                      Good Afternoon All, I have done the following several time to null the TX image when using Rocky 3.7 and think it works right but I would be interested in
                      Message 10 of 19 , Nov 16, 2012
                      • 0 Attachment
                        Good Afternoon All,

                        I have done the following several time to null the TX image when using Rocky 3.7 and think it works right but I would be interested in feedback, positive or negative.

                        Rocky 3.7 continues the RX function when in TX with the RXTX Ensemble transceiver.  The RX antenna connection is open to the antenna path via Q10 biased off.  Moreover, the RX antenna connection over to the QSD circuit is shorted to ground by Q11 and the QSD circuit is disabled by the /OE lines of U10 being allowed to be pulled to 5 volts with Q9 off.

                        What I have done is to clip a lead from the top lead of R63 to circuit ground to enable the QSD circuit and get an  Rocky RX spectrum display.  This allows the use of the Rocky TX balance adjustment to "null" the TX image.  It probably is necessary also to reduce the TX level output to keep the RX function from saturating even with the antenna input grounded.

                        Any thoughts?

                        Thanks and 73,
                        Tony KB9YIG



                        On Fri, Nov 16, 2012 at 1:28 PM, kk4dcf <oohay@...> wrote:
                         


                        >
                        > Maybe, but only if you admit it:) WSPR chat scrolls off the bottom, as far as I know it gets lost. So I thought I could mention that
                        > without accusing anybody in particular.
                        > Don't stop trying, learn what to do. WSPR is good for QRP. Given good conditions 1 watt will reach everywhere on 40m and above. And
                        > much less may be used successfully.
                        >

                        I'm certain it was me. The issue was that I built the kit with TX jumpers crossed and RX jumpers straight for PSDR and then started using linux instead. I forgot I had done that.

                        That mistake points out to me that I do not have the equipment needed to do this. Especially the most basic testing gear, another receiver.

                        The other major issue is that I don't have a viable home antenna. I've tried a handful of configurations and while I seem to be able to transmit decently (per WSPR and the 1 QSO I've had in the past week) the receive performance is terrible (also per WSPR and the 1 QSO). I expect to setup portable in a good open space next week to try and confirm my issues are antenna related. If that truly is the case then I'm probably just going to sell this all off and try again with a commercial rig in a few years when I move.

                        James.


                      • Alan
                        ... Subject: Re: [softrock40] Re: What s the most TX power anyone has amplified an RXTX to? Just out of curiosity... ... Rocky 3.7 and think it works right but
                        Message 11 of 19 , Nov 16, 2012
                        • 0 Attachment
                          ----- Original Message -----
                          Subject: Re: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...


                          >I have done the following several time to null the TX image when using
                          Rocky 3.7 and think it works right but I would be interested in feedback,
                          positive or negative.

                          Tony,

                          I need a lot of thought and experimenting to be sure.
                          My first reaction was that it is a pity it needs Rocky. Not too many use it and quite a few find it does not work on their system.

                          But the principle does not need Rocky.
                          Two separate SDR programs could be used. The one that is intended to be used for transmitting and another one to monitor, temporally
                          with the RX soundcard selected.
                          Then with your R63 clip, or a switch, the RX SDR program could monitor the TX from the other SDR program.
                          Does that sound right?

                          73 Alan G4ZFQ



                          Rocky 3.7 continues the RX function when in TX with the RXTX Ensemble
                          transceiver. The RX antenna connection is open to the antenna path via Q10
                          biased off. Moreover, the RX antenna connection over to the QSD circuit is
                          shorted to ground by Q11 and the QSD circuit is disabled by the /OE lines
                          of U10 being allowed to be pulled to 5 volts with Q9 off.

                          What I have done is to clip a lead from the top lead of R63 to circuit
                          ground to enable the QSD circuit and get an Rocky RX spectrum display.
                          This allows the use of the Rocky TX balance adjustment to "null" the TX
                          image. It probably is necessary also to reduce the TX level output to keep
                          the RX function from saturating even with the antenna input grounded.

                          Tony KB9YIG
                        • John Marvin
                          The two SDR program idea should work. The only problem I see is that there will be a conflict trying to control the si570. You should be able to work around
                          Message 12 of 19 , Nov 16, 2012
                          • 0 Attachment
                            The two SDR program idea should work. The only problem I see is that
                            there will be a conflict trying to control the si570. You should be
                            able to work around that by configuring the SDR program you are using
                            for receive to use a softrock40 device, i.e. configure it so that it
                            believes it is connected to a device where it can't control the center
                            frequency and it should be happy.

                            Of course, someone should actually try this to see if there are any
                            other problems. An alternative to using Rocky would be highly desirable.

                            John
                            AC0ZG

                            On 11/16/2012 12:17 PM, Alan wrote:
                            >
                            > ----- Original Message -----
                            > Subject: Re: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...
                            >
                            >
                            >> I have done the following several time to null the TX image when using
                            > Rocky 3.7 and think it works right but I would be interested in feedback,
                            > positive or negative.
                            >
                            > Tony,
                            >
                            > I need a lot of thought and experimenting to be sure.
                            > My first reaction was that it is a pity it needs Rocky. Not too many use it and quite a few find it does not work on their system.
                            >
                            > But the principle does not need Rocky.
                            > Two separate SDR programs could be used. The one that is intended to be used for transmitting and another one to monitor, temporally
                            > with the RX soundcard selected.
                            > Then with your R63 clip, or a switch, the RX SDR program could monitor the TX from the other SDR program.
                            > Does that sound right?
                            >
                            > 73 Alan G4ZFQ
                            >
                            >
                            >
                            > Rocky 3.7 continues the RX function when in TX with the RXTX Ensemble
                            > transceiver. The RX antenna connection is open to the antenna path via Q10
                            > biased off. Moreover, the RX antenna connection over to the QSD circuit is
                            > shorted to ground by Q11 and the QSD circuit is disabled by the /OE lines
                            > of U10 being allowed to be pulled to 5 volts with Q9 off.
                            >
                            > What I have done is to clip a lead from the top lead of R63 to circuit
                            > ground to enable the QSD circuit and get an Rocky RX spectrum display.
                            > This allows the use of the Rocky TX balance adjustment to "null" the TX
                            > image. It probably is necessary also to reduce the TX level output to keep
                            > the RX function from saturating even with the antenna input grounded.
                            >
                            > Tony KB9YIG
                            >
                            >
                            >
                            >
                            > ------------------------------------
                            >
                            > Yahoo! Groups Links
                            >
                            >
                            >
                          • warrenallgyer
                            Chris I have built a number of the RXTX Ensembles and one Peaberry and have checked all of them with a spectrum analyzer. I think you need have no worries
                            Message 13 of 19 , Nov 16, 2012
                            • 0 Attachment
                              Chris

                              I have built a number of the RXTX Ensembles and one Peaberry and have checked all of them with a spectrum analyzer. I think you need have no worries about taking the Softrocks exciter signal up to high power levels. It is relatively easy to get 50 dB of transmitter image rejection and the harmonics generated by the standard build are better than 40 dB down except for the cases identified in the notes for the low bands of the 80/40, 40/30/20, and 30/20/17 builds. The low bands DO need the external filter but -40 dB is easily achieved without extraordinary measures. I think the stock unit, properly aligned per Robbie's notes, will be fine.

                              If you are doing SSB you will want to limit the audio drive so that the unit stays well under one watt out. Otherwise you will get non-linearity and resulting compression. And, of course, you will need to assure the follow-on amplification stages are linear. But I really see no issues. This is a solid clean design when properly aligned.

                              Warren Allgyer - W8TOD

                              --- In softrock40@yahoogroups.com, Chris Wilson <chris@...> wrote:

                              > 16/11/2012 14:36
                              >
                              > As I said, I was just curious as to how much power people
                              > realistically run from these things, and my thoughts were whether they
                              > could be made clean enough to be unobtrusive at high power output
                              > levels, or whether the fact the majority are QRP tends to hide any
                              > nasties from the fellow spectrum users. Is a soundcard based SDR TX
                              > bound to be dirtier than a good conventional transmitter? Or can the
                              > Softrock RXTX package be amplified to serious levels without becoming
                              > unsociable, and without major doctoring?
                              >
                              > --
                              > Best Regards,
                              > Chris Wilson. 2E0ILY
                              >
                            • warrenallgyer
                              Tony I think this idea is great. I am a little concerned however about doing it with reduced drive level. I use cheap USB or built in audio cards (walking
                              Message 14 of 19 , Nov 16, 2012
                              • 0 Attachment
                                Tony

                                I think this idea is great. I am a little concerned however about doing it with reduced drive level. I use cheap USB or built in audio cards (walking carefully here..... don't want to restart THAT war)... and I have found that the channel to channel levels do not always track that well as you change the overall level. So the relative audio gains at the reduced level may not be the same when you bring the drive back up and, as a result, your image rejection at operating level may suffer.

                                Of course you could use external audio pads to reduce the level but that is complicated and they would need to be carefully matched as well.

                                My 2 cents.

                                Warren Allgyer - W8TOD

                                --- In softrock40@yahoogroups.com, "Parks, Tony" <kb9yig@...> wrote:
                                >
                                > Good Afternoon All,
                                >
                                > I have done the following several time to null the TX image when using
                                > Rocky 3.7 and think it works right but I would be interested in feedback,
                                > positive or negative.
                                >
                                > Rocky 3.7 continues the RX function when in TX with the RXTX Ensemble
                                > transceiver. The RX antenna connection is open to the antenna path via Q10
                                > biased off. Moreover, the RX antenna connection over to the QSD circuit is
                                > shorted to ground by Q11 and the QSD circuit is disabled by the /OE lines
                                > of U10 being allowed to be pulled to 5 volts with Q9 off.
                                >
                                > What I have done is to clip a lead from the top lead of R63 to circuit
                                > ground to enable the QSD circuit and get an Rocky RX spectrum display.
                                > This allows the use of the Rocky TX balance adjustment to "null" the TX
                                > image. It probably is necessary also to reduce the TX level output to keep
                                > the RX function from saturating even with the antenna input grounded.
                                >
                                > Any thoughts?
                                >
                                > Thanks and 73,
                                > Tony KB9YIG
                                >
                                >
                                >
                                > On Fri, Nov 16, 2012 at 1:28 PM, kk4dcf <oohay@...> wrote:
                                >
                                > > **
                                > >
                                > >
                                > >
                                > > >
                                > > > Maybe, but only if you admit it:) WSPR chat scrolls off the bottom, as
                                > > far as I know it gets lost. So I thought I could mention that
                                > > > without accusing anybody in particular.
                                > > > Don't stop trying, learn what to do. WSPR is good for QRP. Given good
                                > > conditions 1 watt will reach everywhere on 40m and above. And
                                > > > much less may be used successfully.
                                > > >
                                > >
                                > > I'm certain it was me. The issue was that I built the kit with TX jumpers
                                > > crossed and RX jumpers straight for PSDR and then started using linux
                                > > instead. I forgot I had done that.
                                > >
                                > > That mistake points out to me that I do not have the equipment needed to
                                > > do this. Especially the most basic testing gear, another receiver.
                                > >
                                > > The other major issue is that I don't have a viable home antenna. I've
                                > > tried a handful of configurations and while I seem to be able to transmit
                                > > decently (per WSPR and the 1 QSO I've had in the past week) the receive
                                > > performance is terrible (also per WSPR and the 1 QSO). I expect to setup
                                > > portable in a good open space next week to try and confirm my issues are
                                > > antenna related. If that truly is the case then I'm probably just going to
                                > > sell this all off and try again with a commercial rig in a few years when I
                                > > move.
                                > >
                                > > James.
                                > >
                                > >
                                > >
                                >
                              • Alan
                                ... Subject: [softrock40] Re: What s the most TX power anyone has amplified an RXTX to? Just out of curiosity... ... Yes, I also have noticed variations in
                                Message 15 of 19 , Nov 16, 2012
                                • 0 Attachment
                                  ----- Original Message -----
                                  Subject: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...


                                  >I am a little concerned however about doing it with reduced drive level. I use cheap USB or built in audio cards (walking carefully
                                  >here..... don't want to restart THAT war)... and I have found that the channel to channel levels do not always track that well as
                                  >you change the overall level. So the relative audio gains at the reduced level may not be the same when you bring the drive back up
                                  >and, as a result, your image rejection at operating level may suffer.
                                  >

                                  Yes, I also have noticed variations in gain between channels as the volume slider, or drive slider is changed.
                                  Image rejection needs to be finally adjusted with these controls set for operation at maximum required output.

                                  I as hoping that when I tested it would not be necessary to reduce TX output. And wondering if there was a way to even further
                                  reduce the stray signals getting into the receiver.
                                  But it will be a while before I try.

                                  73 Alan G4ZFQ
                                • irbsurfing
                                  Hi Chris, As well as ensuring that the image rejection is adjusted correctly you need to be sure that your soundcard is not emitting significant broadband
                                  Message 16 of 19 , Nov 20, 2012
                                  • 0 Attachment
                                    Hi Chris,
                                    As well as ensuring that the image rejection is adjusted correctly you need to be sure that your soundcard is not emitting significant broadband noise.

                                    My setup uses an EMU USB0202 familiar to many, it works well on Rx but on Tx its noise floor is terrible, it has a high noise peak at about 10kHz which will modulate the QSE and give you strong noise peaks on each side of your carrier. Even playing music with good speakers you can hear a hiss (it might be faulty of course!).
                                    It measures about 20dB worse than an FT-817 in 2.7kHz BW at a 10kHz offset and consequently as it stands I would not use it on the air at all, let alone amplified to the legal limit!
                                    To fix it I had to change the capacitors in the QSE and add another pole of filtering. Then it was just about acceptable. It really requires some outboard filtering also. Flex Radio had issues like this in the early days and I recommended a filter in the lead from the sound card, the document is still available from their website.
                                    Not sure how other cards compare but I'm sure that the Delta44 for example, is much better in this respect. If you have a USB0202 find a way to check it first before going on the air!
                                    Andrew
                                    G4XZL

                                    --- In softrock40@yahoogroups.com, Chris Wilson <chris@...> wrote:
                                    >
                                    >
                                    >
                                    > >
                                    >
                                    > > ----- Original Message -----
                                    > > Subject: [softrock40] Re: What's the most TX power anyone has
                                    > > amplified an RXTX to? Just out of curiosity...
                                    >
                                    > > Another related question may be "What is the largest spurious
                                    > > signal transmitted from a Softrock, (or other SDR)."
                                    >
                                    > > On WSPR "Chat" the other day I came across someone who was
                                    > > transmitting without having checked his TX IQ was correct. Transmitting
                                    > > on the wrong frequency.
                                    > > He also knew nothing about setting TX IQ balance so when the IQ was
                                    > > set correctly his image may have been only 25dB down.
                                    > > If he had a fault he could have been transmitting simultaneously on
                                    > > both frequencies without knowing. The same as "mirrored"
                                    > > receiving.
                                    >
                                    > > A good understanding of what is involved is necessary before
                                    > > amplifying mistakes. Any soundcard SDR transmitter needs careful
                                    > > setting by someone who at least understands the basics. A receiver must be used to check.
                                    >
                                    > > I sometimes wonder when immediately after building a Softrock
                                    > > somebody says "I want more power". It took me quite a while to get a
                                    > > fair understanding of the Softrock and software.
                                    >
                                    > > 73 Alan G4ZFQ
                                    >
                                    >
                                    >
                                    >
                                    > 16/11/2012 14:36
                                    >
                                    > As I said, I was just curious as to how much power people
                                    > realistically run from these things, and my thoughts were whether they
                                    > could be made clean enough to be unobtrusive at high power output
                                    > levels, or whether the fact the majority are QRP tends to hide any
                                    > nasties from the fellow spectrum users. Is a soundcard based SDR TX
                                    > bound to be dirtier than a good conventional transmitter? Or can the
                                    > Softrock RXTX package be amplified to serious levels without becoming
                                    > unsociable, and without major doctoring?
                                    >
                                    > --
                                    > Best Regards,
                                    > Chris Wilson. 2E0ILY
                                    >
                                  • Alan
                                    ... Subject: [softrock40] Re: What s the most TX power anyone has amplified an RXTX to? Just out of curiosity... ... Andrew, If it is your 0202 and not
                                    Message 17 of 19 , Nov 20, 2012
                                    • 0 Attachment
                                      ----- Original Message -----
                                      Subject: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...


                                      >
                                      >
                                      > Hi Chris,
                                      > As well as ensuring that the image rejection is adjusted correctly you need to be sure that your soundcard is not emitting
                                      > significant broadband noise.
                                      >
                                      > My setup uses an EMU USB0202 familiar to many, it works well on Rx but on Tx its noise floor is terrible, it has a high noise peak
                                      > at about 10kHz which will modulate the QSE and give you strong noise peaks on each side of your carrier.

                                      Andrew,

                                      If it is your 0202 and not anything else then it must be faulty.
                                      Many use that, I'm sure it would have been mentioned by now.
                                      Here http://g4zfq.alotspace.com/RightMarkTests/E-MUTrackerPre%20_%20USB192.htm is my test on a Tracker Pre. This is basically a 0202
                                      with preamp, not used of course.

                                      A soundcard must be bad to seriously affect a transmit signal. As long as it is not overdriven I would expect noise and hum to be
                                      well below the signal level.

                                      73 Alan G4ZFQ


                                      Even playing music with good speakers you can hear a hiss (it might be faulty of course!).
                                      > It measures about 20dB worse than an FT-817 in 2.7kHz BW at a 10kHz offset and consequently as it stands I would not use it on the
                                      > air at all, let alone amplified to the legal limit!
                                      > To fix it I had to change the capacitors in the QSE and add another pole of filtering. Then it was just about acceptable. It
                                      > really requires some outboard filtering also. Flex Radio had issues like this in the early days and I recommended a filter in the
                                      > lead from the sound card, the document is still available from their website.
                                      > Not sure how other cards compare but I'm sure that the Delta44 for example, is much better in this respect. If you have a USB0202
                                      > find a way to check it first before going on the air!
                                    • irbsurfing
                                      Hello Alan, Well, as I said mine might be faulty! I was shocked at how bad it was. I will try running the Rightmark Analyser and see how it compares to your
                                      Message 18 of 19 , Nov 21, 2012
                                      • 0 Attachment
                                        Hello Alan,
                                        Well, as I said mine might be faulty! I was shocked at how bad it was.
                                        I will try running the Rightmark Analyser and see how it compares to your Tracker Pre, thanks for posting the links. I will report back.
                                        Thanks,
                                        Andrew

                                        --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
                                        >
                                        >
                                        > ----- Original Message -----
                                        > Subject: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...
                                        >
                                        >
                                        > >
                                        > >
                                        > > Hi Chris,
                                        > > As well as ensuring that the image rejection is adjusted correctly you need to be sure that your soundcard is not emitting
                                        > > significant broadband noise.
                                        > >
                                        > > My setup uses an EMU USB0202 familiar to many, it works well on Rx but on Tx its noise floor is terrible, it has a high noise peak
                                        > > at about 10kHz which will modulate the QSE and give you strong noise peaks on each side of your carrier.
                                        >
                                        > Andrew,
                                        >
                                        > If it is your 0202 and not anything else then it must be faulty.
                                        > Many use that, I'm sure it would have been mentioned by now.
                                        > Here http://g4zfq.alotspace.com/RightMarkTests/E-MUTrackerPre%20_%20USB192.htm is my test on a Tracker Pre. This is basically a 0202
                                        > with preamp, not used of course.
                                        >
                                        > A soundcard must be bad to seriously affect a transmit signal. As long as it is not overdriven I would expect noise and hum to be
                                        > well below the signal level.
                                        >
                                        > 73 Alan G4ZFQ
                                        >
                                        >
                                        > Even playing music with good speakers you can hear a hiss (it might be faulty of course!).
                                        > > It measures about 20dB worse than an FT-817 in 2.7kHz BW at a 10kHz offset and consequently as it stands I would not use it on the
                                        > > air at all, let alone amplified to the legal limit!
                                        > > To fix it I had to change the capacitors in the QSE and add another pole of filtering. Then it was just about acceptable. It
                                        > > really requires some outboard filtering also. Flex Radio had issues like this in the early days and I recommended a filter in the
                                        > > lead from the sound card, the document is still available from their website.
                                        > > Not sure how other cards compare but I'm sure that the Delta44 for example, is much better in this respect. If you have a USB0202
                                        > > find a way to check it first before going on the air!
                                        >
                                      Your message has been successfully submitted and would be delivered to recipients shortly.