ELECRAFT K2 - Page 7

VFO Linearization I.F. Amplifier Alignment
Make sure the bottom cover is securely attached. L34, located near the right front corner of the RF board, is used
to
Allow the K2 to stabilize for at least 10 minutes at room peak the output of the I.F. amplifier.
temperature (approx. 20-25°C). (
Note:
Avoid using a high-
wattage
Using the wide end of the plastic tuning tool, adjust the slug in
L34 until it is near the top of the can.
Stop turning the
slug
work lamp direct above the K2 during calibration. With the top
cover removed, this could heat the RF board to a higher
when it appears to be at the top or when
you feel resistance.
temperature than would ever be seen during normal operation.)
Connect the internal frequency counter cable to the VCO
output test point (TP1).
Turn L34’s slug one full turn clockwise (down into the can).
Use the procedure listed below to linearize the VFO. If you see
Set the band to 40 meters using
BAND +
or
BAND -
. Select CW
any
INFO
messages, refer to Troubleshooting.
Normal and FL2 (700 Hz nominal bandwidth).
1. Use
BAND +
or
BAND -
to select 40 meters. Select CW normal
Make sure the RF GAIN control is fully clockwise (max. gain).
mode and filter FL1.
Disconnect the antenna from J4, if one was connected.
2. Set the VFO to anywhere in the range 7000-7100 kHz.
Tap
PRE/ATTN
until the PRE annunciator turns on.
3. Enter the menu and select
CAL PLL
, then hold
a
second time to start the VFO linearization sequence.
Connect a pair of headphones (stereo or mono) to the front
panel jack, and turn the AF GAIN control to about midway.
4. The frequency counter will show the VCO frequency as it
decreases through a range of about 10-13 kHz. (The letter "
d
"
Slowly tune the VFO to locate the weak internally-generated
will flash each time a calibration data point is stored.)
signal near 7000 kHz. If you can't hear the signal at all, you may
have a receiver problem. Try the 40-meter Band Pass Filter
5. When calibration is completed (4-8 minutes), you'll see the
Alignment, below, then refer to Troubleshooting if necessary.
message
End
on the LCD. You can then tap any switch to
return to normal operation. If you see an INFO message rather
While listening to the signal at 7000 kHz, adjust L34 for best
than
End
, refer to Troubleshooting (Appendix E).
signal strength and lowest noise. This setting occurs at about 1 to
1.5 turns below the top of the can. (You can use your DMM on
AC
volts, at the speaker jack, to obtain a more sensitive indication.)
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