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2G Mode

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  • Sam Wetterlin
    I recently posted about how a simple cable move can enable the MSA to operate in the 1-2 GHz range, instead of the normal 0-1 GHz range. This involves routing
    Message 1 of 3 , Aug 18, 2009
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      I recently posted about how a simple cable move can enable the MSA to operate in the 1-2 GHz range, instead of the normal 0-1 GHz range. This involves routing the Mixer 1 output directly to the IF2 amp, skipping the cavity filter and Mixer 2. I hope soon to test a board that will make the switch back and forth a little easier, using just an external jumper.

      The actual operating range goes a little over 2 GHz, but I refer to it as 2G mode, as opposed to the normal 1G Mode.

      For anyone interested, I posted in the Files section two screen shots taken in 2G mode. Note that at the moment the software does not support 2G mode, so the frequencies displayed on the graph are the normal 1G frequencies that the MSA "thinks" it is tuning to, not the higher 2G frequencies that it is actually tuning to.

      The first is an SA scan of a signal of approximately 2070 MHz, from a rather crappy signal generator. In SA/2G mode, the signal and an image 21.4 MHz away will be displayed; I zeroed in to eliminate the image. Because 2G mode skips the losses of the cavity filter and Mixer 2, the displayed signal strength is higher than the actual signal strength.

      <http://f1.grp.yahoofs.com/v1/YCSLSne2DRRUDYEFLT8d2zsIZupNPAs6z9-lC8pFkznfomRM4096HP-3lagEXAfn7UfttgHFrN-gr8sRLha2Og/2G%20Mode/2070.tif>

      The second is a VNA scan of a coax Tee with a 1" coupler attached to one leg, acting as an open stub, creating a trap at about 1700 MHz.

      <http://f1.grp.yahoofs.com/v1/YCSLSne2DRRUDYEFLT8d2zsIZupNPAs6z9-lC8pFkznfomRM4096HP-3lagEXAfn7UfttgHFrN-gr8sRLha2Og/2G%20Mode/Tee.tif>

      The VNA in 2G mode depends on PLO3 as the signal source. I created an external output for PLO3, but there is also plenty of PLO3 in the normal TG output to get a VNA/2G scan of modest dynamic range. Not to get into the details here, but I also installed an amplifier on the TG output. The amp has many advantages, one of which is that I end up with stronger PLO3 content to be used in 2G mode.

      There is also a 3G mode, in which the SA can cover 2-3 GHz (actual high frequency limit not yet tested). That requires no hardware changes at all; it's a complete freebie. I still haven't figured out how to do the VNA in 3G mode, though.

      Sam W.
    • exgator1966
      Sam-Would you post the ExpressPCB files for the 1G/2G diplexer. Thanks, Ken Holt
      Message 2 of 3 , Aug 25, 2009
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        Sam-Would you post the ExpressPCB files for the 1G/2G diplexer.

        Thanks,

        Ken Holt


        --- In spectrumanalyzer@yahoogroups.com, "Sam Wetterlin" <swetterlin@...> wrote:
        >
        > I recently posted about how a simple cable move can enable the MSA to operate in the 1-2 GHz range, instead of the normal 0-1 GHz range. This involves routing the Mixer 1 output directly to the IF2 amp, skipping the cavity filter and Mixer 2. I hope soon to test a board that will make the switch back and forth a little easier, using just an external jumper.
        >
        > The actual operating range goes a little over 2 GHz, but I refer to it as 2G mode, as opposed to the normal 1G Mode.
        >
        > For anyone interested, I posted in the Files section two screen shots taken in 2G mode. Note that at the moment the software does not support 2G mode, so the frequencies displayed on the graph are the normal 1G frequencies that the MSA "thinks" it is tuning to, not the higher 2G frequencies that it is actually tuning to.
        >
        > The first is an SA scan of a signal of approximately 2070 MHz, from a rather crappy signal generator. In SA/2G mode, the signal and an image 21.4 MHz away will be displayed; I zeroed in to eliminate the image. Because 2G mode skips the losses of the cavity filter and Mixer 2, the displayed signal strength is higher than the actual signal strength.
        >
        > <http://f1.grp.yahoofs.com/v1/YCSLSne2DRRUDYEFLT8d2zsIZupNPAs6z9-lC8pFkznfomRM4096HP-3lagEXAfn7UfttgHFrN-gr8sRLha2Og/2G%20Mode/2070.tif>
        >
        > The second is a VNA scan of a coax Tee with a 1" coupler attached to one leg, acting as an open stub, creating a trap at about 1700 MHz.
        >
        > <http://f1.grp.yahoofs.com/v1/YCSLSne2DRRUDYEFLT8d2zsIZupNPAs6z9-lC8pFkznfomRM4096HP-3lagEXAfn7UfttgHFrN-gr8sRLha2Og/2G%20Mode/Tee.tif>
        >
        > The VNA in 2G mode depends on PLO3 as the signal source. I created an external output for PLO3, but there is also plenty of PLO3 in the normal TG output to get a VNA/2G scan of modest dynamic range. Not to get into the details here, but I also installed an amplifier on the TG output. The amp has many advantages, one of which is that I end up with stronger PLO3 content to be used in 2G mode.
        >
        > There is also a 3G mode, in which the SA can cover 2-3 GHz (actual high frequency limit not yet tested). That requires no hardware changes at all; it's a complete freebie. I still haven't figured out how to do the VNA in 3G mode, though.
        >
        > Sam W.
        >
      • swetterlin
        I have now posted the documentation for the diplexer, and the ExpressPCB schematic and PCB layout, on my website at http://www.wetterlin.org/sam/ If you want
        Message 3 of 3 , Aug 25, 2009
        • 0 Attachment
          I have now posted the documentation for the diplexer, and the ExpressPCB schematic and PCB layout, on my website at

          http://www.wetterlin.org/sam/

          If you want to go directly to the PCB layout, it is at

          http://www.wetterlin.org/sam/SA/xG_Modes/Diplexer_1G_2G.pcb

          Sam W.


          --- In spectrumanalyzer@yahoogroups.com, "exgator1966" <kenholt2@...> wrote:
          >
          > Sam-Would you post the ExpressPCB files for the 1G/2G diplexer.
          >
          > Thanks,
          >
          > Ken Holt
          >
          >
          > --- In spectrumanalyzer@yahoogroups.com, "Sam Wetterlin" <swetterlin@> wrote:
          > >
          > > I recently posted about how a simple cable move can enable the MSA to operate in the 1-2 GHz range, instead of the normal 0-1 GHz range. This involves routing the Mixer 1 output directly to the IF2 amp, skipping the cavity filter and Mixer 2. I hope soon to test a board that will make the switch back and forth a little easier, using just an external jumper.
          > >
          > > The actual operating range goes a little over 2 GHz, but I refer to it as 2G mode, as opposed to the normal 1G Mode.
          > >
          > > For anyone interested, I posted in the Files section two screen shots taken in 2G mode. Note that at the moment the software does not support 2G mode, so the frequencies displayed on the graph are the normal 1G frequencies that the MSA "thinks" it is tuning to, not the higher 2G frequencies that it is actually tuning to.
          > >
          > > The first is an SA scan of a signal of approximately 2070 MHz, from a rather crappy signal generator. In SA/2G mode, the signal and an image 21.4 MHz away will be displayed; I zeroed in to eliminate the image. Because 2G mode skips the losses of the cavity filter and Mixer 2, the displayed signal strength is higher than the actual signal strength.
          > >
          > > <http://f1.grp.yahoofs.com/v1/YCSLSne2DRRUDYEFLT8d2zsIZupNPAs6z9-lC8pFkznfomRM4096HP-3lagEXAfn7UfttgHFrN-gr8sRLha2Og/2G%20Mode/2070.tif>
          > >
          > > The second is a VNA scan of a coax Tee with a 1" coupler attached to one leg, acting as an open stub, creating a trap at about 1700 MHz.
          > >
          > > <http://f1.grp.yahoofs.com/v1/YCSLSne2DRRUDYEFLT8d2zsIZupNPAs6z9-lC8pFkznfomRM4096HP-3lagEXAfn7UfttgHFrN-gr8sRLha2Og/2G%20Mode/Tee.tif>
          > >
          > > The VNA in 2G mode depends on PLO3 as the signal source. I created an external output for PLO3, but there is also plenty of PLO3 in the normal TG output to get a VNA/2G scan of modest dynamic range. Not to get into the details here, but I also installed an amplifier on the TG output. The amp has many advantages, one of which is that I end up with stronger PLO3 content to be used in 2G mode.
          > >
          > > There is also a 3G mode, in which the SA can cover 2-3 GHz (actual high frequency limit not yet tested). That requires no hardware changes at all; it's a complete freebie. I still haven't figured out how to do the VNA in 3G mode, though.
          > >
          > > Sam W.
          > >
          >
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