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70246Re: Protect USB Si570 from parasitic RF in shack.

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  • yl2gqn
    Nov 20, 2012
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      Hello,

      Thank you for your answers and advice's. I found the following steps a necessary to avoid that problem:

      1. Good ground system on shack;
      2. Good quality USB cables with RF chokes.

      The low SWR is important but if you have 500 WTTS out and even 1.1:1 VSWR but have not above things - you will have a problems.

      For last weekend I'm rebuild my ground system and add more good quality chokes to wires. During LZ Contest do not have any problems with parasitic RF using 300W PA.

      Regards,
      Andy, YL2QN

      --- In softrock40@yahoogroups.com, VP <ly2bos@...> wrote:
      >
      > I had same problems, I guess that most important
      > thing is to tune your antenna's to low VSWR.
      >
      > 73, Valentinas / LY2BOS
      >
      >
      > At 09:32 PM 11/10/2012, you wrote:
      > >
      > >
      > >
      > >----- Original Message -----
      > >Subject: [softrock40] Protect USB Si570 from parasitic RF in shack.
      > >
      > > > Probably someone here can help me with some
      > > ideas to resolve my problem. Time from time
      > > without any systematic, the PowerSDR
      > > > software lost Si570 USB interface. I need
      > > re-plug USB cable from Softrock to notebook and
      > > set checkbox again in PowerSDR. See
      > > > attached image for details. The same can be
      > > also with Rocky (but without any error screen -
      > > simple Rocky lost control for Si570).
      > > >
      > > > This situation often occurs in next situations:
      > > > - after switch antenna;
      > > > - in case high SWR in antenna;
      > > > - also PowerSDR lost Si570 even 50W
      > > transmitter working in few meters from Softrock setup;
      > > >
      > > > Looks like Si570 USB interface very sensible to parasitic RF.
      > > >
      > >
      > >Yes, I cannot offer any specific advice. You
      > >must experiment until you cure it.
      > >Ferrites, maybe change ground configuration.
      > >Make sure your antenna system is good, that you have not got RF in the shack.
      > >the procedure is the same as for any other setup.
      > >
      > > > The USB ground is separate from regular
      > > ground of Softrock and power amplifier. Looks I
      > > have some ground loops. How is better
      > > > solve this problem ?
      > > >
      > >
      > >It is designed to be separate, others do not
      > >report problems. It is done to prevent ground
      > >loops. But you may have ground loops
      > >through other connections.
      > >
      > >73 Alan G4ZFQ
      > >
      > >
      >
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