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Re: DC-DC converter for Ensemble RX II

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  • ve3mic
    Right you are Alan! In my haste, I neglected to look at the power supply schematics before I sent my original post regarding the DC-DC converter. No 12VDC is
    Message 1 of 22 , May 30, 2011
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      Right you are Alan!

      In my haste, I neglected to look at the power supply schematics before I sent my original post regarding the DC-DC converter. No 12VDC is required at all, since that 12VDC supply is immediately regulated down to 5V. And correct again, the Si570 is powered from the USBus.

      I may try adding a "filtered USB powered" feed once my kit is finished.

      Thanks all who responded to my post.
      73 de Mike, VE3MIC


      --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
      >
      >
      > ----- Original Message -----
      > Subject: RE: [softrock40] Re: DC-DC converter for Ensemble RX II
      >
      >
      > >The current on the 5v RX side (after the regulator) can not be more than a
      > >few milliamps
      >
      > Yes, I was forgetting the Si570 is fed directly from the USB power.
      >
      > As Roger said Tony posted his method
      > <http://groups.yahoo.com/group/softrock40/message/54144> He did not mention
      > the method used in the V4 Softrock.
      >
      > 73 Alan G4ZFQ
      >
    • jor
      Hi Mike, Dan Taylou has design a swticher power supply for the Norcal 2030 stransceiver. Think about the noise in and output must be well filterd and the
      Message 2 of 22 , May 31, 2011
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        Hi Mike,

        Dan Taylou has design a swticher power supply for the Norcal 2030 stransceiver.

        Think about the noise in and output must be well filterd and the electronis screend in a tin box.
        Also LINEAR has switchers IC for low noise.

        As far as i now the max output from the USB port is 500 mA and with Lap-Tops may be les.
        See in my file " PE1KTH SDR AND SOUNDCART INFO"

        73' Joris PE1KTH



        --- In softrock40@yahoogroups.com, "ve3mic" <ve3mic@...> wrote:
        >
        > Right you are Alan!
        >
        > In my haste, I neglected to look at the power supply schematics before I sent my original post regarding the DC-DC converter. No 12VDC is required at all, since that 12VDC supply is immediately regulated down to 5V. And correct again, the Si570 is powered from the USBus.
        >
        > I may try adding a "filtered USB powered" feed once my kit is finished.
        >
        > Thanks all who responded to my post.
        > 73 de Mike, VE3MIC
        >
        >
        > --- In softrock40@yahoogroups.com, "Alan" <alan4alan@> wrote:
        > >
        > >
        > > ----- Original Message -----
        > > Subject: RE: [softrock40] Re: DC-DC converter for Ensemble RX II
        > >
        > >
        > > >The current on the 5v RX side (after the regulator) can not be more than a
        > > >few milliamps
        > >
        > > Yes, I was forgetting the Si570 is fed directly from the USB power.
        > >
        > > As Roger said Tony posted his method
        > > <http://groups.yahoo.com/group/softrock40/message/54144> He did not mention
        > > the method used in the V4 Softrock.
        > >
        > > 73 Alan G4ZFQ
        > >
        >
      • vbifyz
        Yesterday I have tried connecting the USB power and ground to the analog power and ground in my Ensemble II RX. I used a small ferrite toroid with about 10
        Message 3 of 22 , May 31, 2011
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          Yesterday I have tried connecting the USB power and ground to the analog power and ground in my Ensemble II RX. I used a small ferrite toroid with about 10 turns of 26AWG pair (+5 and ground on 2 wires wound together) for RF noise suppression.
          I didn't see any additional RF noise, but the central peak became prominent (60Hz and about 10-15 harmonics on each side). This is a classic ground loop. The only way break the ground loop in this configuration is to add isolation transformers to the audio output. I may try this next weekend.

          73, Mike

          --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
          >
          >
          > ----- Original Message -----
          > Subject: [softrock40] DC-DC converter for Ensemble RX II
          >
          >
          > I'm not sure anyone can predict if you will be troubled by USB noise. I
          > tried something like this, a quick check showed no ill effects but I did not
          > make it permanent.
          >
          > 73 Alan G4ZFQ
          >
        • Alan
          ... Subject: [softrock40] Re: DC-DC converter for Ensemble RX II ... It is not the only way. A ground loop is due to two, or more connections between the
          Message 4 of 22 , Jun 1, 2011
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            ----- Original Message -----
            Subject: [softrock40] Re: DC-DC converter for Ensemble RX II


            > Yesterday I have tried connecting the USB power and ground to the analog
            > power and ground in my Ensemble II RX. I used a small ferrite toroid with
            > about 10 turns of 26AWG pair (+5 and ground on 2 wires wound together) for
            > RF noise suppression.
            > I didn't see any additional RF noise, but the central peak became
            > prominent (60Hz and about 10-15 harmonics on each side). This is a classic
            > ground loop. The only way break the ground loop in this configuration is
            > to add isolation transformers to the audio output.

            It is not the only way.
            A ground loop is due to two, or more connections between the Softrock and
            computer.
            It is always possible to make this just one, difficult maybe, if you have
            not made it easy to experiment with removing the grounds.
            Start by breaking the ground in the audio lead.
            The best results I've had were by bonding everything to a good ground. I
            then found that introducing a ground loop made no difference.

            73 Alan G4ZFQ
          • n6gn
            This is just a note to the list to say that I had good luck with building a DC-DC converter to generate 12 VDC from the USB derived 4.3 VDC on a QRP2000 Si570
            Message 5 of 22 , Jun 3, 2011
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              This is just a note to the list to say that I had good luck with building a DC-DC converter to generate 12 VDC from the USB derived 4.3 VDC on a QRP2000 Si570 synthesizer and used as LO for a slightly modified Ensemble II RX.

              The synthesizer is essentially a stand-alone version of those in the SoftRocks. I got mine from KM5H. Since I had both the synthesizer and an Ensemble RX II that was xtal'd on 40M, I thought it would be handy to use the synth and to power it all from the single USB connection. The result requires only antenna input, USB connection and I/Q cable.

              In addition, I dropped R16 to ~8K ohms so the 0 dBm from the LVDS of the synth would drive it and also widened the Ensemble RX input BPF to become mainly a high pass filter with ~ 10 MHz corner. To do that I removed C4, made C3 162 pf and made L4 only 9 turns instead of the 34 it previously had as 40M filter.

              The results are better than I thought they would be. Though I built the DC-DC converter with SMT parts (dead bug mounted) keeping the total clustered and with short connections, I figured that there might be serious problems from the 500 kHz oscillator in the LT1372. As it turned out, there really weren't any particular problems even down on 160 and 80M (where the filter was rolled off some but still letting some signal through).

              If anyone else wants to do this, all I did was implement the example circuit from the data. See http://www.linear.com/product/LT1372.

              I'm now using it with an ASUS netbook and the package makes a portable all band receiver about the size of a sheet of paper.
              I think the Ensemble/synth pulls ~ 200 mA from the 5 VDC on the USB port, but I didn't actually measure current into the finished unit.

              Glenn n6gn
            • Alan Campbell
              OK, time for me to expose my ignorance again... Why insist on 12V output? Specifically, I m looking at the schematic for the Ensemble II and the only chip
              Message 6 of 22 , Jun 5, 2011
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                OK, time for me to expose my ignorance again... Why insist on 12V output?

                Specifically, I'm looking at the schematic for the Ensemble II and the only chip using the +12V is the 78L05 - which then spits out +5V. At up to 100mA (by datasheet).
                Anything over 7-8V is wasted in the 78L05 and can even cause thermal shutdown.

                I read one web page that mentioned using a 9V battery to run the Ensemble II.  Looking at the circuit for the LT1372, I'd suggest dropping R1 for a lower output voltage would be more efficient.
                Less power produced, less wasted.

                Still, as long as it works, that's the main thing. Experimenting can be a lot of fun.

                -- Alan Campbell
                   PF95ie


                From: n6gn <n6gn@...>
                To: softrock40@yahoogroups.com
                Sent: Saturday, 4 June 2011 1:53 PM
                Subject: [softrock40] Re: DC-DC converter for Ensemble RX II

                 


                This is just a note to the list to say that I had good luck with building a DC-DC converter to generate 12 VDC from the USB derived 4.3 VDC on a QRP2000 Si570 synthesizer and used as LO for a slightly modified Ensemble II RX.

                The synthesizer is essentially a stand-alone version of those in the SoftRocks. I got mine from KM5H. Since I had both the synthesizer and an Ensemble RX II that was xtal'd on 40M, I thought it would be handy to use the synth and to power it all from the single USB connection. The result requires only antenna input, USB connection and I/Q cable.

                In addition, I dropped R16 to ~8K ohms so the 0 dBm from the LVDS of the synth would drive it and also widened the Ensemble RX input BPF to become mainly a high pass filter with ~ 10 MHz corner. To do that I removed C4, made C3 162 pf and made L4 only 9 turns instead of the 34 it previously had as 40M filter.

                The results are better than I thought they would be. Though I built the DC-DC converter with SMT parts (dead bug mounted) keeping the total clustered and with short connections, I figured that there might be serious problems from the 500 kHz oscillator in the LT1372. As it turned out, there really weren't any particular problems even down on 160 and 80M (where the filter was rolled off some but still letting some signal through).

                If anyone else wants to do this, all I did was implement the example circuit from the data. See http://www.linear.com/product/LT1372.

                I'm now using it with an ASUS netbook and the package makes a portable all band receiver about the size of a sheet of paper.
                I think the Ensemble/synth pulls ~ 200 mA from the 5 VDC on the USB port, but I didn't actually measure current into the finished unit.

                Glenn n6gn



              • n6gn
                Alan, Probably a good point in general. 12 VDC isn t particularly magic. However it does potentially give a bit more headroom before distortion in the OpAmps.
                Message 7 of 22 , Jun 6, 2011
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                  Alan,
                  Probably a good point in general. 12 VDC isn't particularly magic. However it does potentially give a bit more headroom before distortion in the OpAmps. I'm surprised that they aren't run from it instead of the 5 VDC of the SR Ensemble RX design. Maybe I've missed something obvious though.

                  Also, I don't know that there is a linear correlation between output voltage on the switching regulator and overall efficiency. At least, I'd suspect for very low outputs, even with all else equal (which it never is!) that diode drop in the switcher would begun to hurt.

                  Still, if someone is looking for alternative ways of powering a SoftRock/Si570 combination there's no requirement to provide 12V.

                  I think the most useful thing I found is that switching regulator hash needn't be a severe problem. I suspect that the switched capacitor DC-DC converter solutions - which generally are limited to 2x voltage- might work just as well as the inductive switcher I used.

                  I'd say the good news is that it isn't difficult to combine existing SR hardware/synthesizers to make a small, portable, all-mode, general coverage receiver that has decent performance very inexpensively.

                  Best,
                  Glenn n6gn

                  > OK, time for me to expose my ignorance again... Why insist on 12V output?
                  >
                • The Silver Fox
                  Just for reference: I ve run my softrocks with 9V DC power for a long time without any noticeable negative effects but I ll admit that I ve not pushed them to
                  Message 8 of 22 , Jun 6, 2011
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                    Just for reference:  I’ve run my softrocks with 9V DC power for a long time without any noticeable negative effects but I’ll admit that I’ve not pushed them to the limit on transmit.

                    73’s

                    Alan – W6ARH

                     

                    From: softrock40@yahoogroups.com [mailto:softrock40@yahoogroups.com] On Behalf Of n6gn
                    Sent: Monday, June 06, 2011 8:10 AM
                    To: softrock40@yahoogroups.com
                    Subject: [softrock40] Re: DC-DC converter for Ensemble RX II

                     

                     



                    Alan,
                    Probably a good point in general. 12 VDC isn't particularly magic. However it does potentially give a bit more headroom before distortion in the OpAmps. I'm surprised that they aren't run from it instead of the 5 VDC of the SR Ensemble RX design. Maybe I've missed something obvious though.

                    Also, I don't know that there is a linear correlation between output voltage on the switching regulator and overall efficiency. At least, I'd suspect for very low outputs, even with all else equal (which it never is!) that diode drop in the switcher would begun to hurt.

                    Still, if someone is looking for alternative ways of powering a SoftRock/Si570 combination there's no requirement to provide 12V.

                    I think the most useful thing I found is that switching regulator hash needn't be a severe problem. I suspect that the switched capacitor DC-DC converter solutions - which generally are limited to 2x voltage- might work just as well as the inductive switcher I used.

                    I'd say the good news is that it isn't difficult to combine existing SR hardware/synthesizers to make a small, portable, all-mode, general coverage receiver that has decent performance very inexpensively.

                    Best,
                    Glenn n6gn

                    > OK, time for me to expose my ignorance again... Why insist on 12V output?
                    >

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