[Skimmertalk] CWSL and HPSDR

[Bob Wilson, N6TV]

Most people are using the 14:1 transformer <https://www.kkn.net/~n6tv/XFMR>
plus a 10 dB preamp. to create a "close enough" 50 ohm input to the Classic
RedPitaya (125-14).

On the new Red Pitaya SDR (122.88-16), none of that is required.  I
produced an S-9 signal by transmitting very low power into dummy load and
listening on "calibrated" receiver (Elecraft K3, non-SDR, connected to
Skimmer antenna), then I went through the S-Meter calibration procedure
with HDSDR using the same signal and antenna and ended up with a correction
factor of -11.3 dBm.  I didn't try doing this on all the bands though. This
was with the default scaling factor 16 in the Extio_CWSL dialog.

73,
Bob, N6TV


On Thu, Jun 20, 2019 at 3:25 AM <dd5xx at web.de> wrote:

> Hi Brad,
>
> you never will succeed to calibrate your RP with HDSDR/CWSL_Tee and get
> correct values reported, simply said because you are not using a 50 Ohm
> input on the classic RedPitaya/StemLab. Even if you try, you would realize
> that your S-meter are not linear 160-10m when you cross-check with a real
> meter. I don't know how this behaves on the new RedPitaya with the 50 Ohm
> input, maybe someone tested it already and can give you feedback.
>
> 73
> Saki, DD5XX
>
>
> Gesendet: Donnerstag, 20. Juni 2019 um 03:58 Uhr
> Von: "Brad Denison" <brad.denison at gmail.com>
> An: skimmertalk at contesting.com
> Betreff: [Skimmertalk] CWSL and HPSDR
> Thanks Bob - perhaps I did not word my question correctly. I am more
> interested in knowing that if I put in a calibrated signal source (S9
> for example) to my receivers I get that value reported back correctly.
> The only way I know how to do this with a QS1R or a RP is by using
> CWSL TEE & HPSDR, which by default, never returns the value I know I
> am injecting. MY FDM-S2 for example requires no fiddling with
> parameters for the software to yield the appropriate S9 on the
> display.
>
> For now I am not worried about the frequency of spots or SNR of spots
> - just that my receivers are showing S9 when I put in a S9 (or any
> other value for that matter).
>
>
> Perhaps this clarification will help with an answer.
>
>
> Brad, W1NT
>
>
> >If you can "see" band noise on all bands with scale factor 16 (the
>
> >default), you're fine. No need to calibrate the HDSDR S-meter; CW Skimmer
> >doesn't calculate the S/N ratio that way. The scale factor you set in
> >HDSDR's Extio_CWSL dialog has no effect on the reports generated by CW
> >Skimmer Server. Better to check that your frequency of your spots matches
> >those reported by calibrated skimmers such as those at KM3T.
> >
> >The feature of Aggregator that would compare your frequency calibration to
> >those of all others was disabled a long time ago to improve server
> >performance, as I understand it.
>
> >
>
> >73,
>
> >
>
> >Bob, N6TV
>
> >
>
> >
>
> On Wed, Jun 19, 2019 at 6:04 PM Brad Denison <brad.denison at gmail.com
> <http://lists.contesting.com/mailman/listinfo/skimmertalk>> wrote:
>
> >
>
> >
>
> >* So, it's summer and I figured while not too busy I would do a health
> check*
>
> >* on my skimmers. Using CWSL and HPSDR is not something that I have
> bothered *>* with too much in detail but I observe that there is an s-meter
> calibration *>* procedure and also that the scale factor parameter changes
> the S-meter when *>* that parameter is adjusted. *> >* So my ask to the
> experts is when using a calibrated signal source what is *>* the
> appropriate method to setup HDSDR using CWSL such that I can ensure my *>*
> skimmers are healthy in the levels that they are hearing? *> >* Thanks, *>
> >*
> Brad, W1NT *>* _______________________________________________ *>*
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