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Monday, August 9, 2021

Mythbuster Video #15 The Mythbuster Signal As Seen in the NA5B WebSDR


Mehmet NA5B has an excellent WedSDR receiver in Washington D.C., about 9 miles east of me. I often use it to check my signal quality. I think this video shows that the 10 pole crystal filter is working and is producing a signal with very sharp drop-off outside the 2.7 kHz passband. You should focus your attention to the passband (yellow vertical lines) near 3895 kHz. That's me.

Once, when I was describing my 40 meter DIGI-TIA to an SDR guy, he seemed surprised that I was using a -- gasp -- crystal filter. "Your skirts must be atrocious!" he said. My HDR sensibilities were deeply offended.

I had hoped that the 10 pole crystal filter would produce skirts so nearly vertical as to make my signal indistinguishable (in the waterfalls) from the SDR signals. At least at this low signal level, it appears to be working.

1 comment:

  1. Bravo Bill! Nice pattern and the QSO roundtable sure gave you high marks -- I didn't even hear "sounds OK for a Homebrew Radio" Must be the 10 Pole Filter,

    Pete

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