A base-mounted tuner may have difficulty matching certain lengths.
According to my ICOM AT-150 manual, we should avoid multiples of half-waves.
The manual offers the formula 300/freq X 0.5 X integers 1, 2, 3, etc. (You
figure it separately for each integer but stop when the product is longer
than your antenna is.) For all your desired frequencies, you do the
calculations, then avoid that length. You will develop a list of lengths
that are "bad" and you avoid an antenna of that length.

I did the calculations and saved them with the manual. I observe from my
own results that 43 feet is in a sweet spot between 39.5 feet (which is bad
for 12m) and 45.8 feet (which is bad for 30m). Never mind who uses those
bands or doesn't. I simply ran the numbers for he frequencies we can bring
up and that's where the chips fell. By the way, ICOM says the antenna
should be more than 7 meters (23 feet).

Here are the "bad" lengths that I got, in meters.
5.05 - 5.30
6.00 - 6.03
6.99 - 7.14
8.25 - 8.30
10.10 - 10.71
12.00 - 12.05
13.99 - 14.85
15.15 - 15.81
16.51 - 16.60

So, obviously, some good lengths fall between those "bad" lengths. Here are
the midpoints of the "sweet spots" that remain in play:
7.75m (25.42 feet)
9 m (29.52 feet)
11.5m (37.72 feet)
13m (42.64 feet)
15m (49.21 feet) but this is a minimal sweet spot
16.25 (53.3 feet )

The 43' antenna is at one of those sweet spots. CAUTION: If you use a long
pigtail, that could mess things up.

I hope this helps.

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"Gareth's Downstairs Computer" wrote in message
news
What is so special about that magical length, for it does
not appear to be resonant anywhere!