A couple of weeks ago, Ken Brown, N6KB, asked:
"Can you discern any difference in the noise blanker function with/without the
Inrad roofing filter? For instance when band conditions are such that your
ability to copy a signal is not limited by close in strong signals, and is
limited by QRN and you are using the noise blanker, what works best? Inrad
roofing filter in or out?"
I had an experience yesterday, I'd like to share. During a time when I had
strong line noise, some of the locals were working 5T0CW on 30 meters, and I
couldn't copy at all. The Omni VI noise blanker helped, but not enough. Then
I turned my NAR switch off ( which disengages both my narrow IF filter-- INRAD
753-- and the 600 Hz roofing filter. Now I could copy the 5T station! The
noise blanker was more effective in smoothing out the harsh hiss of the line
noise in this case. When the line noise is not present, I always have better
copy with the NAR switch on.
I've been considering dedicating the Omni VI to CW only by wiring the roofing
filter so it is in line all the time (using the NAR switch in its normal
mode). That would provide me with options in terms of CW selectivity (since I
have the VI, not the VI+). Now I'm wondering if this would compromise my noise
blanker.
73,
Chuck NI0C
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