Elecraft K2 Owner's Manual User Manual

Page 79

LECRAFT

40-Meter Transmitter Alignment

To align the transmitter you’ll need some means for

monitoring power output as you adjust the band-pass filters. An analog
wattmeter or oscilloscope is ideal. However, in the instructions that
follow we’ll assume that you’re using the K2’s built-in digital
wattmeter, which will also provide satisfactory results.

Set the POWER control for 2.0 watts.

Switch to the 40 meter band and set the VFO for about 7100 kHz.

Locate the 40-meter band-pass filter inductors, L1 and L2, and be

prepared to adjust them using the wide end of the tuning tool.

In the following steps you’ll place the K2 into "TUNE" mode

by holding

T U N E

. You should limit key-down periods to about 5 or 10

seconds during tune-up for safety reasons. If you see or smell smoke
turn the K2 off and refer to Troubleshooting.

Note: While in tune mode, it is normal to see power drift upward
several tenths of a watt. You may also see a sudden jump in power
during alignment. Adjust the POWER control as needed to maintain
the output between 1 and 2 watts.

Put the K2 into tune mode and activate the built-in wattmeter by

holding

T U N E

. Using the alignment tool, adjust L1 for maximum

output. Tap any switch to exit TUNE mode.

Enter tune mode again and adjust L2 for maximum output. Tap

any switch to exit.

If necessary, repeat the adjustment of L1 and L2 two or three

times to be sure that you have the inductors peaked correctly. If you
cannot get power output to 2.0 watts or higher, see Troubleshooting.

Make sure the bar graph is set for DOT mode using the GRPH

menu entry.

Set power output to 5.0 W using the POWER control.

Tap

D I S P L A Y

to enter voltage/current display mode. When this

display is selected, you can use

T U N E

to check your voltage and

current in transmit mode.

Enter tune mode and note the change in voltage and current.

Current drain at 5 watts is typically 1.3 to 1.6 amps.

If the current

reading is much higher than this, or if the voltage drops more than 1 V,
you may have a problem in the transmitter, load, or power supply (see
Troubleshooting).

Return to frequency display using the

D I S P L AY

switch.

Set the POWER control for 10.0 watts.

Enter tune mode just long enough to verify that the wattmeter

reads approximately 10 watts. If you then switch to voltage/current
display and hold

T U N E

again, you should see a current drain of

typically 1.8 to 2 amps. If you see a "HI CUR" warning message (high
current), use CAL CUR to set your transmit current limit higher. If
current is much higher than 2 A, see Troubleshooting.

This completes transmitter alignment and test on 40 meters.

The K2 transmitter is most efficient at 10 watts and higher; current drain at

5 watts CW may be higher than expected. This is unavoidable because the K2
is capable of up to 15 W output. Also, for a given power level, SSB
transmission requires more transmitter "overhead" to prevent distortion.