MFJ MFJ-784B, Instruction Manual, Page: 61 / 74

MFJ-784B Instruction Manual
Filter Description 5-9
Manual Notch Filter
Use: Removes unwanted tones or heterodynes.
Removes up to 2 very narrow frequency ranges and passes all others.
The manual notch filter allows the use of two frequency-independent manually
tunable notch filters. The
Tunable Filters left and right knobs control the
individual notch frequencies ( f1 & f2 ).
The manual notch has two different frequency ranges and widths: one for the
CW filter and one for the other filters. When using the CW filter the notch is
narrower, 45 Hz @ -40 dB, and has a frequency range of 300 Hz to 1000 Hz
(same as the CW filter). In all other modes the notch is wider, 85 Hz @ -40 dB,
and has a frequency range of 150 Hz to 3400 Hz.
For Example: There is RTTY in your SSB audio. After engaging the Manual
Notch button, use the Tunable Filters
left and right knobs
to
notch the two RTTY tones at 2125 and 2295 Hz.
Typical Manual Notch Filter Response
Frequency (Hz)
dB
-120
-100
-80
-60
-40
-20
0
0 500 1000 1500 2000 2500 3000 3500 4000