Balanced line antenna tuner1/17/2024 ![]() ![]() de 2016 Ive built an antenna and tuner for an AM radio before by putting. True active peak reading lighted cross-needle SWR/Wattmeter allow you to read SWR, true peak or average forward and reflected power all at a glance on 300/3000 Watt ranges.Īre you running QRO? Consider one of these MFJ 976 Legal Limit Balanced Line Tuners from DX Engineering. line feeding a balanced antenna or radiation of the antenna onto the feed line. ![]() As a result, most high-end ATU manufacturers now use 1:1 current. ATUs tend to have their lowest efficiency and highest loss of power at very low impedances. MFJ 976 1500 Watt antenna tuners have a heavy duty 1:1 current balun that gives you superb balance and stays cool even at 1.5 kW. Further, in the event that the antenna system’s impedance is low, which happens often, the 4:1 balun will transform its impedance 4x lower, presenting a very low impedance to the ATU. You'll also have excellent 10 meter performance because of MFJ's low minimum capacitance, exclusive Self-Resonance Killer™, and high-Q AirCore™ roller inductor with silver plated contacts. Four separate 500 pF capacitors in two gangs contribute a total of 2000 pF for highly efficient low loss separation on 160 meters. There's no complicated switching between high and low impedance and switching in additional capacitance or L-networks. MFJ's wide-range T-network delivers simple, fast, three-knob tuning. MFJ 976 tuners also tune random wires and coax-fed antennas. They tune any balanced lines including 600 ohm open wire line, 450/300 ohm ladder lines, 300/72 ohm twin lead, shielded or unshielded. These tuners provide superb balance, very wide matching ranges (12-2000 ohms) and continuous 1.8-30 MHz coverage including all WARC bands! They handle a full 1500 Watts SSB and CW. It stays cool even at maximum power.ĭoublet, horizontal loop, vertical loop, quad, double extended Zepp, Lazy H, W8JK antennas all give efficient multi-band operation when fed with balanced lines.MFJ 976 Legal Limit Balanced Line Tuners are 1500 Watt fully balanced antenna tuners. The balun is made of 50 ferrite beads on RG-303 Teflon coax to give exceptional and efficient isolation. The tuning components are mounted symmetrically to insure electrical balance.Ī 1:1 current balun is placed on the low impedance 50 input side to convert the balanced T-Network to unbalanced operation. The MFJ-974HB 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 inductors for 6 and 160 Meters. 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-974HB tunes any balanced lines including 600 Ohm open wire line, 450/300 Ohm ladder lines, 300/72 Ohm twin lead - shielded or unshielded. You can even adjust for highly efficient broadband low-Q operation or use higher Q when you encounter extreme loads.Ī 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.Ī ground post is provided to ground one output terminal so you can also tune random wires and coax fed antennas. Tuning is fast and easy - just three tuning controls. ![]() Handles 300 Watts SSB PEP and 150 Watts CW. The MFJ-974HB gives you excellent current balance, very wide matching range(12-2000 Ohms) and covers 1.8 through 54 MHz continuously including all WARC bands, 160 Meters, 6 Meters and the new 60 Meter band. It meets todays needs and even surpasses the Johnson Matchbox outstanding performance. But, it had a severely limited matching range and covered only 80, 40, 20, 15 and 10 Meters. It gives you superb current balance throughout its very wide matching and frequency range.įor decades, the Johnson Matchbox has been the standard of comparison for balanced line tuners. The MFJ-974HB is a fully balanced true balanced line antenna tuner.
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