Re: New to the list


I think I'm missing something here.  You keep mentioning wired LAN connections.  I'm talking about running the SDR stand alone with wspr daemon running on the same pi that is connected to the SDR hardware and no LAN connection at all, but just logging spots to an internal file for upload at a later time.  I still don't know if it is possible to run wspr daemon the way I propose and how wspr daemon software would connect to the SDR software in this case, ...I suppose through defining a common port or using a third application which acts as a virtual port, I am no expert on the like but wouldn't this get around virtually (no pun) all the connectivity issues that cause ground loops and common mode noise injection?


---------- Original Message ----------
From: Glenn Elmore <n6gn@...>
Date: July 14, 2021 at 6:28 PM

Only measurement will tell for sure but it isn't uncommon for a even a
co-located device to create a loop with power supply and wired LAN
connections. Shielding probably won't matter or help. If the entire
arrangement is within a small volume then self-capacitance can be low
and paths in one line and out another, through the Kiwi 'grounds' , may
not be enough to cause a problem but even then  edges whether LAN or
SMPS may cause QRM.   Try it and see. If you always have a symmetric
antenna then it may be possible to short out only the
desired/differential part and verify that any remaining CM is well below
the measurement level.

On 7/14/21 4:19 PM, VE3VXO wrote:
> If I can run the SDR and WD on a single Pi in a shielded box with no
> LAN then the only external connections will be a short battery lead
> and the coaxial lead in.  The phased pair I described are on 50 ft
> double shielded LMR-100A feedlines so as short as possible and a
> lumped element Pi network for the phase delay feeding into a
> minicircuits ZFSCJ-2-1 inverting combiner. The chokes I made should
> give about 5k ohms at the low end of HF, will this not be sufficient?
> Joe


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