ELECRAFT K2 - Page 86

ELECRAFT 85
Filter Settings (CAL FIL)
This section explains how to use C A L F I L to select the
bandwidth and BFO settings. An example appears on the next
page. The Elecraft web site provides information on other filter
setup methods, including a method that uses a personal computer
sound card. For a discussion of how the crystal filter and BFO
settings are related, see page 104.
Basic CAL FIL Setup
1. Connect the frequency counter test cable to TP2 (BFO).
2. Set AF GAIN high enough to hear some background noise.
3. Switch to a band between 160 m and 17 m. (The sideband is
inverted on 15 m and above, which may be confusing during
filter setup.)
4. Select CW mode using
M O D E . If a bar appears above the C,
the K2 is in CW Reverse mode; hold
C W R V to select CW
Normal mode.
5. Tap
X F I L until F L 1 is selected.
6. Tap
M E N U and scroll to C A L . Hold E D I T to move the
underline to O F F , then scroll until you see C A L F I L .
Finally, hold
E D I T again to activate the filter display.
Filter Bandwidth Display
The initial C A L F I L display shows the present filter bandwidth
and the operating mode, e.g. F L 1 1 . 5 0 c . The number 1 . 5 0
indicates a bandwidth of roughly 1.50 kHz.
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This parameter has
a range of 0 . 0 0 - 2 . 4 9 . Above 2 . 4 9 , the parameter changes to
O P 1 - O P 5 , which can be used to select optional filters. For
example, the filter on the SSB adapter (KSB2) is O P 1 .
Note the present bandwidth setting, then try using the VFO knob
to change it. You'll hear the "shape" (or pitch) of the noise
change. (Return to the original bandwidth after experimenting.)
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The number shown should be used only as a relative indication of filter
bandwidth. Actual bandwidth will probably be narrower.
BFO Displays
Tap
B A N D - to display the BFO setting for filter FL1, which will be
similar to B F 1 t 1 1 0 c . The 3-digit number is the BFO control
parameter. This number can be changed using the VFO knob, but
you'll use a different BFO-setting method described below. The letter
t after B F 1 is a reminder that the B F 1 BFO frequency is always used
on transmit, which is important for SSB operation.
Whenever the BFO control parameter is displayed, you can tap
D I S P L A Y to show the actual BFO frequency in kHz. The VFO knob
can then be used to set the BFO directly. This method is used in the
filter-setup example.
Note: After changing the BFO setting, you can tap
A G C to re-
measure and save the BFO information without switching filters. This
is useful if you want to try various BFO settings for a particular filter
to find the one with the best audio peak.
Other CAL FIL Operations
When you're in C A L F I L you can always tap
X F I L to change to the
next filter, tap
M O D E to change modes, and hold C W R V to switch
from CW normal to CW reverse. Whenever you switch modes or
filters, the K2 will first record your new settings, if they have been
changed.
B A N D + switches to the filter bandwidth display, and B A N D - switches
to the BFO display. Tapping
M E N U exits C A L F I L and returns to
the normal display. (On exit from C A L F I L , changes are saved.)
Turning Selected Filters Off
FL2, 3, or 4 can be individually disabled. To turn off a filter, display
the filter bandwidth using C A L F I L , then set the bandwidth number
to O F F . (To get to O F F , go to 0 . 0 0 first, then turn the VFO knob
a bit farther counter-clockwise.)