Hey, folks,
To all of you who have received my filter measurements... I went back and
spent some more time investigating the issue of the low-to-high frequency
rolloff as you saw in my screen shots and that you've heard others refer to.
I made considerable progress in finding a workaround. Tonight, I'm going to
see if I can capture some more measurements and re-send to you all so you
can see the difference. Please stay tuned.
It really boiled down to an alignment issue. I will document the procedure I
used to correct the rolloff so that anybody curious about their audio can
see if they can reproduce my results. I have a theory as to why the radio
looked like it did. The short answer is "operator error", but the longer one
is that to align the IF you have to put the test tone in the right part of
the passband before peaking both IFs. Knowing how the passband looks right
now tells you what correction should be made. Really, anyone who has done
any alignment at all already knows the answer... it just takes me longer
than most folks to realize what's going on!
Anyway, take the screen shots you have now as an example of what a
mis-aligned IF could look like until I can send you some better pictures,
okay? I think you'll be much happier with what you see.
Regards,
Al W6LX
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