Vectronics VEC-884 - Manual (Page 36)

VEC-884 Owner's Manual
Operation Error! Main Document Only.-10
Manual Notch Button
When pressed in, this button activates two manually adjustable notch filters.
Each filter removes a very narrow range of frequencies or tones. The manual
notch operates in every filter mode except when the DSP button is out.
The manual notch is often used to notch out one or two unwanted tones on
CW, voice or digital modes. A manually adjusted notch is the only type of notch
that operates correctly on CW and digital modes. The manual notch can also
remove warbling or buzzing carriers that the automatic notch may ignore. The
manual notch also causes less audio distortion in voice modes than an
automatic notch.
A manual notch does some things better than the automatic notch. In tone
modulated modes the automatic notch wouldn't "know" which tone you wanted
to hear and which tone was the interference. It would remove the good signals
right along with the bad signals. Since the operator can tell which tones are
bad, he/she can use the manual notch to remove them.
The Tunable Filters left and right knobs adjust the frequency of each notch
over the entire audio range of the filter. The manual notch bandwidth is very
narrow. Tones within 100 Hz of each notch frequency will be reduced over ten
thousand times in volume. If you only need to notch one tone, set the other
Tunable Filters control to any end of its range. Doing so will prevent the
unused notch from hurting the quality of the signal you want to hear.
One thing is a little tricky when using the manual notch. Since the manual notch
uses the Tunable Filters left and right knobs to adjust the notch frequencies,
you must select and adjust the correct main filter
before using the manual
notch. The VEC-884 always "remembers" the Tunable Filters left and right
knobs settings when the manual notch is engaged and then the Tunable
Filters left and right knobs will only adjust the two manual notch frequencies.
Another important thing to remember is when you release the Manual Notch
button, the main filter will still remain exactly as it was set. The only thing that
will happen is the notch will turn off. But if you adjust or move either Tunable
Filters left or right knob, the main filter will quickly jump to the current control
settings. If you don't want to loose your original filter settings, don't touch the
Tunable Filters left or right knobs after using the manual notch. You can
adjust and use the notch as much as you like without affecting the original filter
settings whenever the Manual Notch button is "in."