To which part of the band should I tune my Hi-Q wire antenna if my transceiver has an automatic antenna tuner?

Question

I'm attempting to tune my DX-EE Alpha Delta multi-band wire antenna. The instructions state:

The 40 meter sections can be shortened to the SSB section of the band by pulling the wires through the end insulators an additional 3 inches each side, and twisted back on themselves. This length will vary due to the installation site, so check the SWR resonance first. The wires don’t have to be cut. Then, a wide range antenna tuner should be employed to broaden out its bandwidth.

I think what they're saying is, "you can't cover the entire 40m band with this antenna, so trim it to the half you want to use (the upper half, where phone transmissions are allowed), and let your antenna tuner do the rest." Am I right in my interpretation?

When trimming a wire antenna, should you trim it so the VSWR is lowest in the middle of the band of interest or should you trim it so it's lowest at one edge?

This question stems from a previous question. In those graphs you can see that all my wire segments aren't trimmed properly (I may not be able to fix 15m--I'll look in the attic and see if I can unfold some of the wire I folded back).

Answer 1

You should trim it so that the SWR is the same at each edge of your band segment of interest.

If you tune it for the lowest SWR in the middle, you likely will find that the the above condition does not occur and the SWR might be too high at one edge.

Answer 2

You can tune it like Mike Waters says, the idea being to minimize the worst case regardless of where you are in the band.

Or perhaps you use one side of the band more than the other, in which case tune for the part of the band you use the most.

Most likely, it doesn't matter too much either way. As long as the SWR is still within range of your transmitter's tuner, what you're trying to avoid is additional loss due to SWR. Since the feedline to your attic is probably not very long, and the worst-case SWR is probably not that bad, the losses will probably be small.