On 7/1/2023 8:47 AM, Steve L wrote:
I recently discovered several presentations by Rob Sherwood - famous for his
receiver testing. I was fortunate to get to meet him at Hamvention this year
and thanked him for his work. His new(?) message: CLEAN UP THE DIRTY
TRANSMITTERS. And he calls out specific models! BTW, Elecraft was NOT on the
lists, but it is surprising which ‘high end’ transceivers were. It’s worth
reviewing his presentations on the subject - and it kept me from a bad upgrade!
It's good to see that Rob has finally started paying attention to dirty
transmit, but I started working on this ten years ago. My first
publication was jointly with K6XX, the second an analysis of ARRL Labs
data that they sent me in electronic form. The third consists of
measurements in my own lab, using the P3/SVGA in my second radio.
http://k9yc.com/K6XXAmpTalk.pdf (Published Nov 2013)
http://k9yc.com/TXNoise.pdf (published July 2014)
http://k9yc.com/P3_Spectrum_Measurements.pdf (published March 2015)
When I leaked an early version of the ARRL data analysis to someone I
strongly suspected would make sure that Yaesu saw it, they issued a
firmware update that brought their flagship radio, the FTDX5000 from
absolute worst to roughly even with the second worst, ICOM 7800. The
March 2015 shows before and after measurements of a neighbor's Yaesu rig.
While Rob is a great engineer and has done a lot to improve our
receivers, there are some things he doesn't understand, and refuses to
listen to what I've told him to fill in his gaps -- that audio is
dynamic, and that traditional RF test signals are not the way to test
SSB rigs. Rather pink noise, which has been used in pro audio for more
than 40 years, is a far better test signal to expose defects in rigs, an
example of which is, again, Yaesu!
73, Jim K9YC
73, Jim K9YC
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