![]() 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. This tuner was donated to QCWA Chapter 85 and sold at auction to raise scholarship money.I have had two non-working MFJ-989C tuners *given to me* by unhappy users over the years. Physical characteristics: Size: 10.75 x 4.5 x 15 inch (WxHxD), 10 lbs. You can learn more about this tuner in the nice YouTube video by Dave Larsen KK4WW. The MFJ-989 is a T-network tuner that uses a huge roller inductor (with turn counter) and two huge variable capacitors (see pictures below). It includes a front panel switch that allows selection of one of two coaxial antennas, the wire antenna or a balanced feed line antenna, plus a "pass-through" for times when tuning is not necessary. The tuner includes a 300 watt dummy load for easy tune up of your exciter. The tuner is designed to match most antenna systems operating from 1.8 to 30 Mhz and will handle up to 3KW PEP RF output power. The MFJ-989 Antenna Tuner is a high power, manual antenna tuner designed for coaxial fed, single wire and balanced antennas fed with open-wire.
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