[Elecraft] Two KX3 ATU operating tips

[Wayne Burdick]

On a hike to a local park today, I had occasion to use two of the KX3's lesser-known internal ATU features:

1. "Try harder" ATU mode

Having tossed about 25' of wire in a tree and laid another 25' on the ground, I found that the ATU would tune close to 1.0:1 on 60-6 meters, except for 17 meters, where it was 1.9:1. Even though 1.9:1 is an acceptable SWR, a lower SWR can sometimes be obtained by allowing the ATU to try more LC combinations. To do this, simply tap ATU TUNE a second time within 5 seconds of the first match attempt. In my case, a 1.0:1 match was found on the second try.

2. Clearing out old LC data

The KX3 stores ATU LC data for many segments on each band. The LC data required to match a home antenna system is often quite different from what is needed to match a field antenna. So when operating in the field, you may find that clearing all of the LC data for each band used can save a lot of re-tuning time. This is done by locating the ATU MD menu entry, then holding CLR (a switch function of the RIT offset control). Then exit the menu.

Today's situation was typical. I noticed I my SWR was high in different segments on 40 meters and realized it was because of the home-antenna segment data. Rather than retune in each segment I used, I cleared the LC data as described above, then tuned up once in the middle of 40 meters. My SWR was now fairly low across the entire band. I later retuned once in the SSB segment and once in the CW segment.

The ATU will use the LC data from the closest segment that you've tuned, so when setting up a new antenna, you can tune up in as little as one spot (if the antenna is broadband) or as often as within every segment. Segments are on 20-kHz boundaries on most bands (5 kHz on 160 m).

Conditions were good. On 40 m I could be copied all up and down the state running 3 W SSB, aided by the new speech compressor algorithm.

(BTW, for those interested in station weight, my internal-batteries-only KX3 station including antennas and pack comes in at 3.3 lbs.)

73,
Wayne
N6KR