[hpsdr] Penelope vs: PennyLane - final IMD? Mercury diversity?

[Tom Cathey]

Joe / K5SO,
 
Thanks so much for the detailed info.  Being new to SDR, I appreciate the
guidance to get off to a fast start.
 
Yes, K2SDR's null steering demos are impressive. That's just what I'm
looking for. I was almost to the point of buying a Flex 5K just because of
that feature, but my friend and fellow HPSDR member, Frank/WA1GFZ said
there's a better way.  Yes, learning and implementing the HPSDR technology
is exciting and leading edge for ham use.
 
I am impressed to see you have already set up THREE diversity receivers and
playing with even more complex software nulling routines. Count me in as a
beta tester soon. I have a number of high gain, homebrew antenna arrays for
HF that I wish to multi-phase, including Beverages in several directions.
My main bands are 40M and 75M Dxing.  (Check out QRZ.com for some pics of
the antennas.)  Your PowerSDR software work with diversity is much
appreciated, Joe.
 
OK on the Penny and IMD. I have been on a never-ending quest for years to
set up a QRO HF linear amplifier system that was at least -45db 3rd order
IMD. I have accomplished this recently with my big tube amp, but now my
FT-1000D is only about -32 3rd IMD  - a bottleneck problem. Thus the
interest in using the very clean 500 mW Penny output into a chain of SS amps
as an IPA. 
 
BTW, I received an informative email from Hans, DL2MDQ, with charts of IMD
for Penny. Incredible numbers at lower HF freqs and lower power levels
exceeding -70db 3rd.  He also plans to publish some comparable SS amplifier
info concerning CCI amplifiers that will produce higher power -50db F3
results. (Class A)    I was confused  why the PennyWhistle used an average
-32db IP3 linear stage for the very clean Penny exciter.  The bottom line is
when we run QRO on the bands, we have a responsibility to have ultra clean
side products to compensate for our higher power. It's all relative and no
one cares how many db down our products are - it's how loud are we now and
are we causing adjacent channel problems as a result? Every db in better IMD
helps.
 
 
* Another benefit of the HPSDR list is I was contacted by someone who had an
HPSDR kit for sale. Except for the Metis board, an Excalibur and second
Mercury board, I should be up and running in the near future to start some
diversity tests.  But maybe I will need three Merc RX's for your new tests,
Joe.. :-)
 
 
Thanks again for the help and I'll be lurking and reading.
 
73,
Tom, K1JJ
 
 
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