This is a draw back of this design tuner (note the Differential T from MFJ claims ONE best setting is easy to get but this is a different internal design.) Best way to learn is to use 50 watts into an external dummy load of 50 ohms and start with book dial settings. Experiment with many different dial settings and see you get what appears a good match with the dials in many different positions. This should give an arc-free setting, but if this 1.5 kw tuner arcs, 99% chance it is not tuned correctly. Op should start with 50 watts and the book standard dial settings and then start tuning from those points, and turning the knobs in the sequence given in the book. The problem with antenna tuners of this design is that they will show some kind of match (lower SWR) on a WHOLE LOT of dial settings, most of which are not the best settings. The drive belt on the roller inductor which drives only the counter broke. Had the 989C for six years used it twice on G5RV and worked ok on 1KW. It is possible that carefully first reading the manuals for these tuners would be helpful to many who have had problems. IMHO these tuners only need some TLC, modest parts replacement and care in using them. I cleaned and resoldered the bad solder connection and cleaned the coil and replaced its original drive belt with a stronger "Heathkit" drive belt and both tuners have worked flawlessly now for over three years. The second tuner had a poor solder connection and severe carbon arcing on the roller loading coil. These stronger drive belts are often available new on E-Bay for a very modest cost. The problem with one tuner was a broken drive belt which I replaced with a much stronger drive belt designed for use with the old Heathkit SB series linear amplifiers. I use these on occasion up to full legal limit power with no problems whatsoever. Both tuners were easily fixed by me, are in use now and I have not had any problems with either tuner after fixing them. If you have an amplifier, then your tuner must handle the power and match the line.I have had two non-working MFJ-989C tuners *given to me* by unhappy users over the years. The coaxial line outputs are selectable, tuned or direct, with the tuner's matching network in line or with the matching network bypassed, respectively. An internal six-position antenna selector switch selects a built-in 300 watt, 50-ohm dummy load, two coaxial line outputs or a single wire line-balanced output. The built-in balun will work with balanced open wire, twin-lead or twin-axial feedlines. MFJ 989D tuners have rear panel connectors for coaxial and single or two wire feedlines. They will match dipoles, inverted-Vs, verticals, beams, random wires and many other antennas. MFJ 989D legal limit tuners use a roller inductor "T" matching network that continuously tunes all frequencies from 1.8 through 30 MHz. Illumination is provided via a 9-Volt battery or 12 Vdc or 120 Vac with an optional AC adapter. Peak and average forward power, refelected power and SWR are displayed on the illuminated cross needle meter. MFJ 989D tuners are designed to match 50 ohm output amplifiers, transmitters or transceivers to virtually any antenna. MFJ 989D Versa Tuner V Roller Inductor Tuners handle the US amateur legal limit of 1500 watts, CW and SSB.
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