Elecraft KAT2 User Manual

Page 16

Route the ATU control cable approximately as shown in the drawing. If you will not be installing the

battery option at this time, leave a loop of the cable in the indicated position. Secure the ATU control cable
to the speaker and/or battery wiring using at least three of the supplied nylon cable ties.

Thread the binding post into the ground connector, E1 on the ATU control board, through the top

cover's GND hole. Tighten E1 using the large hex wrench supplied with the K2 as a lever. Insert either end
of the hex wrench into the wire-hole in the binding post, and tighten it until the serrated edge of the binding
post digs into the paint. Use an ohmmeter to verify that the binding post shows a very low resistance (< 1 Ω
to the top cover. If the resistance is high, carefully scrape some of the paint away by hand.

Check the orientation of J7 and J8 carefully as described below before turning on power.

Connect the ATU RF cable (J7) to the K2 RF board at P6 (AUX RF). The notch in J7's connector

housing must grip the locking tab of P6. Both the locking tab and notch should face the K2 front panel.
Make sure you have not plugged J7 into the internal battery connector on the RF board (P3), and
that the shield wire in J7 is closest to the side of the K2 when J7 is plugged into P6 on the K2 RF
Board.”

Connect the ATU's control cable (J8) to P4 on the K2 Control board (AUX I/O). The green wire

(indicated by the arrow on J8) corresponds to pin 2 of P4, and that end of J8 should be closest to the top
edge of the K2 Control board. Make sure that J8 is mated with all 10 pins of P4.

Examine both ends of the ATU's control and RF cables for shorted or loose wires.

Bridge Null Adjustment (C55)

Connect a 50-Ω dummy load rated at 5 watts or higher to the ATU's Ant. 1 jack.

Connect a power supply to the K2 and turn on power. (Do not install the top cover at this time.)

Select the 40 meter band (7000-7300 kHz). Set the K2's POWER control for about 5 watts.

If the ANT 2 annunciator is ON, tap the

A N T 1 / 2

button to turn it OFF. This will select antenna 1.

Using the menu, change the ATU mode to CALn (Null). Exit the menu before proceeding.

Turn the FWD and REFL potentiometers on the ATU module fully clockwise (R1 and R2). Set C55

so that its adjustment slot is parallel to the K2's rear panel.

Note: When

T U N E

is activated in the following step, the display will show reflected voltage in millivolts

(e.g., 075 ATU). If C55 is not yet close to the proper position, you'll see HI instead of a number. You
should be able to get a reading of 010 or lower when C55 is properly adjusted.

Locate a small insulated-handle screwdriver, and prepare to adjust C55 on the ATU module. Hold in

the

T U N E

button and release it when you see the display change. Adjust C55 for an indication as close as

possible to 000. Tap or hold

T U N E

again to cancel the CALn display and return to receive mode.

You should find a 000 indication (approx.) over a small range of C55's rotation. Position C55 at

approximately the middle of this range, repeating the previous step as needed. (Note: Due to stray
capacitance on the L-C board, you may not see a 000 indication if you try to use CALn on higher bands.)