[hpsdr] Hermes/ANAN-10 RX spurious signals?

[John Marvin]

  I have a fair amount of spurs on my standalone Hermes.  But I haven't 
done a "fair" test yet.  I'm using a reasonable quality PC power supply, 
but since it is a switching supply it can easily be adding interference. 
What are you using to power your Hermes/ANAN-10?

  I also have it near other electronic equipment. Finally I haven't 
completely enclosed the board in a metal case.  I need to try a test 
with a  battery and some more isolation from potential noise sources.  
However, I'm not quite seeing the same  issue with 10 Mhz multiples. I 
see a little spur at 10 Mhz, nothing at 20 Mhz, a little spur at 30 and 
40 Mhz. I see a big spur at 50 Mhz.

My biggest spurs are at fractions of the 122.88 Mhz main sampling clock, 
i.e. 12.288 Mhz, 24.576, 36.864 and 49.152 Mhz, with the biggest ones 
being 24.576 and 49.152 Mhz. Those are huge.

I would think you could open your case and disconnect the ANAN-10 if you 
wanted to check just the Hermes board by itself.

John
AC0ZG

On 11/10/2012 2:42 PM, Bruce Beford wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> I am interested in hearing from others who have their Hermes/ANAN-10 units
> up and running. I note several spurious signals in the RX, with the antenna
> connector terminated in a 50 Ohm load. There are pretty strong signals on
> the 10MHz clock freq and it's multiples. I have not tried using the external
> input with my GPSDO yet. There are also a few other internally generated
> spurii. I have not cataloged the actual freqs yet. Very easy to check with
> the wideband display of CuSDR.
>
> I would like to determine if these signals are present on a bare Hermes, or
> if they are related to the integration within the ANAN-10 PA and enclosure.
> I am preparing to leave on a business trip shortly, so won't have too much5
> time to tear down to the bare board to investigate.
>
> All comments from those who have actually checked for these appreciated.
> Thanks,
> Bruce, N1RX
>
>
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