With respect to the Omni VI+, AB9M mentioned "TenTec
for that reason provides narrow roofing filters in the
first IF. With the 500 Hz or more likely the 250 Hz
filters selected"
I don't think it's quite right to call these cascaded
9Mhz 1st i.f. filters "roofing filters"
There's actually a wide (15khz?) "roofing filter"
before the 2.4khz 9Mhz filter. A few folks have
experimented (but nothing conclusive ever published)
with replacing that wide roofing filter with a
narrower filter to improve close-in dynamic range
performance.
73,
Barry N1EU
www.albany.net/~bg
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