[Skimmertalk] Red Pitaya vs QS1R - comparison tests with CW Skimmer Server.

[kazeringue at aol.com]

Did you try using a step up transformer at the input?  Even with the 
short, the board's input impedance should be 5K+.

No QS1R here to compare to, but the RP seems comparable to the softrock 
sensitivities.  I'm running RP with a step up transformer at the input. 
Tests with K2AV on 160m show his SNR is averaging 47 on RP.  With the 
softrocks he was averaging closer to 45db from data collected over the 
past 2 years or so.  K2AV is ground wave on 160m, about 8 miles to my 
WSW, rx coming into what should be just about 250 degrees, into the side 
lobe of my K9AY facing EU.

Generally, the current RP set up seems to be reporting more spots with 
skimmer server than the softrocks did with single channel skimmers.  The 
antenna system feeding RP is exact same as it was previously into the 
softrocks.  Some of that may be due to cleaning up the power supply and 
the BCB to knock down the broadcast mixes.  K2AV is 8 miles away, but 
WPTF is less than 2, and is running 50KW.  lol

The transformer is currently 2 transformers cascaded.  The first is 3:1 
turns ratio 5:15 actual turns of #24 on FT-43-50 core.  That output 
feeds into a 4:1 turns ratio.  Actual turns on the second transformer is 
6:25 of same #24 on same ft-43-50 core.  So something like 50 ohms to 7K.

I intend to test more using each transformer individually, as well as 
removing it entirely to see what works best.  Just not there yet with 
testing.  I wasted a bunch of time before I found the info about the OS 
compatibility issue.  Will do that testing after SSCW.

73 de w4kaz