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6 - 80 Meter Balanced Line Antenna TunerThe MFJ-974B is a fully balanced true balanced line antenna tuner. It gives you superb current balance throughout its very wide matching and frequency range.
For decades, the Johnson Matchbox has been the standard of comparison for balanced line tuners. But, it had a severely limited matching range and covered only 80, 40, 20, 15 and 10 Meters.
The MFJ-974B is its successor. It meets today's needs and even surpasses the Johnson Matchbox outstanding performance.
The MFJ-974B gives you excellent current balance, very wide matching range(12-2000 Ohms) and covers 1.8 through 54 MHz continuously including all WARC bands, 6 Meters and the new 60 Meter band. Handles 300 Watts SSB PEP and 150 Watts CW.
Tuning is fast and easy - - just three tuning controls. You can even adjust for highly efficient broadband low-Q operation or use higher Q when you encounter extreme loads.
A large three-inch lighted Cross-Needle SWR/Wattmeter lets you read SWR, peak or average forward and reflected power all at a glance on 300 or 30 Watt ranges. A ground post is provided to ground one output terminal so you can also tune random wires and coax fed antennas.
Compact 7½Wx6Hx8D inches fits anywhere.
The MFJ-974B tunes any balanced lines including 600 Ohm open wire line, 450/300 Ohm ladder lines, 300/72 Ohm twin lead - - shielded or unshielded. Superb current balance minimizes feedline radiation that can cause troublesome TVI and RFI, painful RF bites, mysterious RF feedback problems and radiation pattern distortion.
The MFJ-974B is a fully balanced wide range T-Network using four gear driven 1000-Volt air variable capacitors and high-Q air wound tapped inductor for 80-10 Meters and separate inductor for 6 Meters. The tuning components are mounted symmetrically to insure electrical balance.
A 1:1 current balun is placed on the low impedance 50 input side to convert the balanced T-Network to unbalanced operation. The balun is made of 50 ferrite beads on RG-303 Teflon™ coax to give exceptional and efficient isolation. It stays cool even at maximum power.
Balanced lines give extremely low loss.
Doublet, horizontal loop, vertical loop, quad, double extended Zepp, Lazy H, W8JK antennas all give efficient multi-band operation when fed with balanced lines.
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