70246Re: Protect USB Si570 from parasitic RF in shack.
- Nov 20, 2012Hello,
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.
--- In email@example.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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