60 ELECRAFT
BFO Alignment
The K2 uses a variable-bandwidth crystal filter, allowing the
operator to set up as many as four filter bandwidths for each
operating mode. Each of these filter configurations requires an
appropriate BFO setting, which determines the pitch you hear.
Filter and BFO set up is done with the C A L F I L calibration
function. C A L F I L is described in detail in the Operation section
of the manual, under Calibration Functions. Rather than duplicate
this information here, the instructions and example in the
Operation section will be used.
Make sure the bottom cover is securely attached.
Tap P R E / A T T until the PRE annunciator is turned on.
(Turning the preamp on will provide some background noise so you
can hear the effect of changing filter bandwidths.)
Follow all instructions on page 85 to become familiar with the
C A L F I L function.
Perform the steps in the example on page 86 to set up all
filters. You'll use the filter and BFO data from Table 8-1 (for a
CW-only K2), since the SSB adapter is not installed. If you later
install the SSB adapter, you can easily change the settings to take
advantage of the optimized, fixed-bandwidth SSB filter.
VFO Linearization
Make sure the bottom cover is securely attached.
Allow the K2 to stabilize for at least 10 minutes at room
temperature (approx. 20-25°C). (Note: Avoid using a high-wattage
work lamp direct above the K2 during calibration. With the top
cover removed, this could heat the RF board to a higher
temperature than would ever be seen during normal operation.)
Connect the internal frequency counter cable to the VCO
output test point (TP1).
Use the procedure listed below to linearize the VFO. If you see
any I N F O messages, refer to Troubleshooting.
1. Use
B A N D + or B A N D - to select 40 meters. Select CW normal
mode and filter FL1.
2. Set the VFO to anywhere in the range 7000-7100 kHz.
3. Enter the menu and select C A L P L L , then hold
E D I T a
second time to start the VFO linearization sequence.
4. The frequency counter will show the VCO frequency as it
decreases through a range of about 10-13 kHz. (The letter "d "
will flash each time a calibration data point is stored.)
5. When calibration is completed (4-8 minutes), you'll see the
message E n d on the LCD. You can then tap any switch to
return to normal operation. If you see an INFO message rather
than E n d , refer to Troubleshooting (Appendix E).
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