The antenna will work OK. The VSWR may be a little high due to the low
height. Minimum height should be in excess of 65 feet and most hams
can't get that high!

Working on 20 meters will most likely be difficult without a good tuner.

Deacon Dave, W1MCE

whitehat wrote:

I will be building a center fed 80 m dipole, 62.5 feet
each side of center. The ends will be about 23 feet above
ground but the center is not supported to it sags to about
18 feet. I will feed it directly with about 25 feet of
RG-213 50 ohm coax and connect it to an antenna tuner in
the shack that can tune from 50 to 500 ohms.

This should work okay on 80 m, right?

How well will it do on 20 m?