See the pictures below. Tuning of the 12,17,15,10 and 2 meter, bands are accomplished via shorting or lengthening respective stub. The antenna can be assembled and tuned on the ground. Although, MFJ says in to use a five foot pole when tuning, I installed it on a 3-foot pole and tuned the antenna with no problems. The spokes you see in the picture below are the means of tuning the antenna on the 30,40 and 80 meter bands.
All frequencies are at the low end of the band.
Tuning of the bands above 30 meters are easily done by means of the stubs. 30-meters and below are accomplished by trimming spokes on the loading coils. These bands must be tuned in succession, starting with the 80-meter band. See page 22 of the manual for complete details If you would like a MFJ1798 manual before purchase, you can get one from MFJ's web site. The final installation is on a 30-foot tower with no ground radials.