MFJ MFJ-784B, Instruction Manual, Page: 56 / 74

MFJ-784B Instruction Manual
Filter Description 5-4
BP Filter [2]
Use: Custom Voice, FSK, Custom CW Filter.
Passes narrow to wide frequency width.
This filter is an adjustable band-pass filter. The bandwidth (
BW ) is controlled
by the Tunable Filters right knob. This adjustment is similar to the selectivity
control on a receiver. It can be adjusted from 30 Hz to 2100 Hz. The Tunable
Filters left knob varies the center frequency ( fc ) between 300 Hz and 3400
Hz. This adjustment is very much like the pass band tuning or IF shift control
on high quality receivers.
For example: If the center frequency ( fc ) is adjusted to 2200 Hz and the
bandwidth ( BW ) is adjusted to 600 Hz, all frequencies between
1900 Hz and 2500 Hz will pass. All frequencies not in the
600 Hz bandwidth will be attenuated.
Typical Band-pass Filter Response
Frequency (Hz)
dB
-80
-70
-60
-50
-40
-30
-20
-10
0
0 500 1000 1500 2000 2500 3000 3500 4000