Saturday, April 28, 2012

Cushcraft A3S/A743 Performance

A3S/A743 pointed toward Europe.

Jerry, NG6R, e-mailed me this week in response to my posting on the Cushcraft A3S/A743. Jerry had sold his A3S to another ham who was wondering about getting the A743 add-on kit. He wanted me to share my experience with the antenna.

The specifications don't really change with the 40 or 30m add-on. This was true with my experience. I did the A743 update in-place, with the antenna still on the tower. (Something I'll share in another posting)

The performance on 20/15/10 was the same as before the update. On 40m, it is a dipole -- but a rotatable dipole. Beamwidth is pretty broad, about 100 degrees. There are noticeable nulls off the ends -- and some of that may depend on how high the antenna is mounted. Mine is at 15m (50 feet) high, which is still a little bit low for a 40m antenna.

If you can mount an inverted V or dipole significantly (8-15m) higher than the A3S, you might be better off with a wire antenna than the A743. At my QTH, the 15m high tower is the highest point in the lot, so the A3S/A743 is a great combination. 

In the picture, you can see the 80/40m trap dipole coming off horizontally to the left of the tower at the 12m level. This dipole is broadsize NE/SW. With only 3m difference in height, there's not a lot of difference in the two antennas, with the higher antenna having a slight edge on DX. During some domestic contests, I would rotate the A3S/A743 to point NE, giving me 360 degree coverage on 40m with a flick of the antenna switch.

(The 80/40m dipole has since moved to the micro-shack in Floyd County, GA)

Does it work? You bet. I have 40m WAS and 113 credits on LoTW for 40m, virtually all of them on this antenna. I'd prefer a two-element short 40m yagi, but my tower installation doesn't allow it. The A743 kit only adds a few pounds of weight and increases the turning radius by about a meter. It's a good addition to most A3S installations.

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