My previous posting on the subject assumed a 750hz center for the Inrad
roofing filter. If the center freq is actually 700hz, the lower knee of the
221 filter will intersect the roofing filter's response at -6dB (and not
-10dB). So what you would end up with downstream of the 221 would be a flat
passband for the 125hz passed above the center freq of 500hz (i.e., 500 - 625hz
sidetone) and a downward sloping passband for the 125hz below the center freq
to -6dB at 375hz sidetone. 73,Barry N1EU----- Original Message ----- From:
"Chuck Guenther" Doing this for the standard CW roofing filter (BW = 600 Hz and
Center Freq.= 700 Hz) and the 221 filter (BW = 250 Hz and CF = 500 Hz) will
show thatthe lower -6db cutoff frequency of the composite response will fall
ABOVEthe lower cutoff of your 221 filter,
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