Elecraft K3 Owner's Manual User Manual

Page 24

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, per-mode ‘normal’ settings are also
available as explained below.)

You can alternate between the I and II settings by
holding

I/I I

. This is especially useful when you’re

alternating between a wide and narrow setting
during contest or DX operation.

The I and II settings for VFOs A and B are
independent.

Filter Normalization (NORM)

Standard Settings

To get quickly to a standard per-mode bandwidth
and reset any passband shift or cut, hold

N O R M

(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

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.

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 a 15 kHz 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 K3's standard "NORM" values,
you can save two of your own setups in each mode,
then recall them using the

N O R M

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

N O R M

until you see

<- SA V ->

seconds)

• rotate the knob slightly left or right to save it as

NOR M1

NOR M2

(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

N O R M

until you see

<- NO R ->

(about 1/2 second), then rotate the knob left or right
to recall

NOR M1

NOR M2

Narrow DSP Filter Types

For bandwidth settings of 100 Hz or lower, the K3’s
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

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.