|Amateur Antenna Tuners|
The MFJ-986 3 KW roller inductor tuner lets you get your SWR down to absolute minimum for maximum power out -- something a tapped inductor tuner just can't do. Plus you get a peak reading SWR/Wattmeter, six position antenna switch, balun for balanced lines and full 1.8 - 30 MHz coverage including 160 Meters, MARS and all the WARC bands. A 3-digit turns counter plus a spinner knob gives you precise inductance control -- so you can quickly retune to your frequency. You get a peak and average reading cross-needle meter that shows you SWR, forward and reflected power at a glance! A directional coupler gives you even more accurate readings over a wider frequency range. You get a 6-position antenna switch that lets you select two coax lines and/or random wires (direct or through tuner), balanced line and external dummy load. A new current balun for balanced lines minimizes feedline radiation that causes field pattern distortion, TVI and RF in your shack. Ceramic feed thru insulators for balanced lines withstand high voltages and temperatures.
By replacing the two variable capacitors with a single differential capacitor, you get a wide range T network tuner with only two controls -- the differential capacitor and a roller inductor. That's what you get with the new MFJ Differential-T Tuner that makes tuning easier than ever, gives you minimum SWR at only one setting and has a broadband response that ends constant re-tuning. You'll spend your time QSOing instead of fooling with your tuner. The compact 10 x 4 x 15 inch cabinet has plenty of room to mount the silver-plated roller inductor away from metal surfaces for highest Q --you get high efficiency and more power into your antenna. The wide spaced air gap differential transmitting capacitor lets you run a full 3 KW PEP-- no worries about arcing.
MFJ's Cross-Needle SWR/Wattmeter gives you more accurate SWR and power readings over a wider frequency range with no frequency sensitive adjustments. That's because MFJ's directional coupler gives you up to an order of magnitude higher directivity and coupling factor than conventional circuits . . . plus it gives you a flat frequency response that requires no frequency compensation. The cross-needle meter lets you read forward/reflected power in two ranges: 200/50 and 2000/500 watts. The meter lamp is front panel switched and uses 12 VDC, or 110 VAC with optional MFJ-1312D. A switch lets you select peak or average power readings.
Nearly all commercially built tuners use a "voltage balun". A "voltage" balun forces the voltages to be equal on the two antenna halves. It minimizes unbalanced currents only if the antenna is perfectly balanced--not the case with practical antennas. The MFJ-986 uses a true current balun to force equal currents into the two antenna halves--even if your antenna is not perfectly balanced--so you get minimum unbalanced currents. The current balun gives superior balance over the "voltage" balun. Minimum unbalanced current reduces field pattern distortion--which concentrates your power for a stronger signal--plus it reduces TVI and RF in your shack caused by feedline radiation. View larger.
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