DX Engineering 450 Ohm Ladder Line

DX Engineering 450 Ohm Ladder Line is a transmitting grade low-loss parallel-wire RF feedline featuring a strong, waterproof, UV black polyethylene insulation. To maintain the wire spacing between the conductors while reducing losses, the integral flat plastic material alternates with rectangular openings, which explains the "Window Line" nickname. Capable of handling over 3 kW of RF power, DXE-LL450 is a very low-loss transmission line across HF. It is ideal for exceptionally long feedline runs and for low band wire antennas operated on multiple bands on which the feedpoint impedance can vary significantly, causing mismatch and elevated SWR. Unlike coaxial cables, DX Engineering DXE-LL450 Ladder Line maintains low RF losses at frequencies where antenna feedpoint impedance mismatches cause high SWR. It can provide significantly higher efficiency than coaxial cable when feeding non-resonant antenna systems that are matched with a wide impedance range antenna tuner.

DXE-LL450 450 Ohm Ladder Line is a high-quality flat RF feedline, about 0.938 in. wide (15/16") with two 16-gauge copper-clad steel wire conductors (29 AWG x 19 strands) that provide the strength to hold up for long spans between supports without twisting. It exhibits a nominal impedance of around 400 Ohms and a nominal Velocity Factor of 91 percent.

For proper performance, LL450 Ladder Line must be installed suspended through the air supported by insulators every 25 ft. or less, kept at right angles and several inches away from other wires, and at least one foot away when run parallel to the earth or large metal surfaces. Installing with an axial twist of one turn per 10 ft. can reduce wind, rain and ice loading, RF coupling and RF noise. DXE-LL450 can be mounted with insulators and suspended on metal or wood posts or run along a wood fence line, only if the fence has no wires or metal mesh that couples RF noise or unbalances the feedline.

Often used for non-resonant wire doublet antennas, DXE-LL450 can be more easily terminated outdoors to a DXE-MC20-C4-1 4:1 Balun or a DXE-MC20-1-1T 1:1 Balun. Then, with no inline switches or relays, directly connect the antenna system to a typical indoor wide range antenna tuner using a solid dielectric coax, not foam dielectric, to handle high voltage at high SWR. DXE-213U or DXE-214 Coaxial Cable Assemblies 12 or 18 ft. with PL-259s are perfect for this method, which eliminates the need for a special balanced tuner, and avoids the losses and detuning effects caused by unbalancing when ladder line is routed indoors near wires and ducts.

DXE-LL450 is sold by the foot, previously sold as DXE-LL450-CTL, this is the same ladder line with a new part number. It is also available in spools of 500 ft. DXE-LL450-5C and 1,000 ft. DXE-LL450-1K, which are specified for DX Engineering Reversible Beverage System Antennas.

NOTE: This type of feedline is intended for MF and HF use and is not suitable for use above 54 MHz.

Also consider DX Engineering 300 Ohm Ladder Line, DXE-LL300, an excellent alternative low-loss HF feed line that reduces impedance extremes on non-resonant HF multiband antenna systems.
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