Filter Presets (I/II)
Each operating mode provides two “floating” filter
presets, I and II, which store filter settings on a
per-VFO, per-mode basis (excluding FM). They are
updated continuously as you change filter settings.
Fixed (non-floating) per-mode filter settings are
also available, as explained below.
You can alternate between the I and II settings by
holding the I/II switch. This is especially useful
when you’re alternating between wide and narrow
settings during contest or DX operation.
Filter Normalization (NORM)
Standard Settings
To get quickly to a standard per-mode bandwidth
and reset any passband shift or cut, hold NORM
(normalize). The normalized AF bandwidth is 400
Hz in CW and DATA modes, 2.7 or 2.8 kHz in SSB
modes, and 3.0 kHz for AM
1
.
Whenever you normalize the filter passband,
two small "wings" appear at the left and right ends
of the DSP filter passband graphic as shown below.
Moving any DSP control makes the "wings"
disappear, as a reminder that the passband is no
longer normalized.
1
In AM mode, the I.F. bandwidth required for good
fidelity is about twice the AF bandwidth. This is why a 6
kHz or wider crystal filter is needed to effectively use the
3 kHz NORM setting. If an FM filter is installed, it can
be used in AM mode to provide good fidelity at even
higher AF bandwidth settings.
Custom Settings (NORM1 and NORM2)
In addition to the standard "NORM" values, you
can save two of your own setups in each mode, then
recall them using the NORM function. These setups
are referred to as NORM1 and NORM2.
To save a custom normalization setting:
• set up the filter passband as desired for the
current mode
• hold NORM until you see <
-
SAV
-
> (3
seconds)
• rotate the knob slightly left or right to save it as
NORM1 or NORM2.
(The arrows to the left and right of SAV are a
reminder that you can rotate the knob to get to the
two user-defined normalization settings.)
To recall, hold NORM until you see <
-
NOR
-
>
(about 1/2 second), then rotate the knob left or right
to recall NORM1 or NORM2.
Narrow DSP Filter Selection
For bandwidth settings of 100 Hz or lower, the DSP
normally uses a type of filter that minimizes
ringing: the Finite Impulse Response or FIR filter.
If you’d like steeper filter skirts, and don’t mind a
small amount of ringing, you can select Infinite
Impulse Response” or IIR filters for these
bandwidths. Locate CONFIG:FLx BW menu entry,
then tap 7 until you see IIR ON. Both main and
sub receivers will use the same setting.
IIR filters take longer to change from one
bandwidth to another, so you may hear audio
artifacts when adjusting the DSP controls. If this is
objectionable, use the default FIR filters.
Another narrowband filter alternative in CW
mode is APF (audio peaking filter). This filter has a
very narrow peak (~30 Hz) but very little ringing
due to its broader skirts. See APF, pg. 32.
To Next Page
Loading...
