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DX Engineering Bead Choke Standoff Kits
DX Engineering Bead Choke Standoff Kits bring a practical solution to a serious problem when ferrite chokes are placed directly onto the metal boom at the feedpoint of beam antennas. A number of Amateur Radio operators and antenna engineers have known for years about the superior choking function of many ferrite toroids beads placed directly on the coaxial cable, as compared to standard feedpoint baluns. A more recent revelation is that the proximity of ferrite beads on coax taped to the aluminum boom of the antenna drastically reduces their effectiveness. DX Engineering Bead Choke Standoff Kits are mounting systems, made of fiberglass or acetyl standoff rods (color varies), PVC carriers and stainless steel hardware, available in four versions. Two sizes of PVC cradle tubes handle two different types of RF bead chokes; 3/4 inch outside diameter (OD) ferrite beads on RG-400 size cable, and 1 inch OD ferrite beads on RG-213 size 0.405 in. coax cable. Each are offered with two different boom size clamps, 2 inch OD and 3 inch OD. Bead Choke Standoff Kits simply hold an RF bead choke and feedline 4 inches away from the metal beam antenna boom (or 4 inches away from the metal mast for a dipole). They maintain the optimal choking performance of ferrite beads on coax. Using DX Engineering Bead Choke Standoff Kits, ferrite bead chokes function at peak performance for these key results: • Prevent feedline radiation of RF • Preserve current balance for proper beam antenna pattern • Prevent feedline shield exterior collected noise and signals from entering the antenna and interior of the feedline, resulting in lower noise floor and enhanced reception The absolute superiority of RF chokes made of many beads on the feedline, over the traditional enclosure balun, is becoming better understood in Amateur Radio. They achieve the best possible RF isolation of the feedline from the antenna and provide completely balanced currents at the feedpoint. Plus, they provide quieter reception with reduction of common-mode noise. Keeping Bead RF Chokes away from metal preserves the optimal function of this method of antenna feedpoint current balance and isolation. This mechanical requirement is simple and practical with DX Engineering Bead Choke Standoff Kits.
( 3 )
$65.99
$52.79
Clearance
COMTEK Jerry Sevick W2FMI Series Current Baluns
COMTEK Jerry Sevick W2FMI Series Current Baluns were inspired by the writing of Jerry Sevick, as published in his book "Understanding, Building, and Using Baluns and Ununs" also available from DX Engineering. COMTEK baluns are value-engineered for maximum performance at a reasonable cost. They provide a superb, efficient transition between unbalanced coax and balanced antennas. COMTEK Baluns feature: * Jerry Sevick design with modern improvements from DX Engineering's in-depth balun research and development * Unique high-voltage compensating capacitors for unequaled SWR bandwidth * Outstanding ferrite-mix coated toroid core with special design to accommodate close coupling without excessive stress * Exceptionally high and consistent common mode impedance across the specified bandwidth, which provides isolation where it is needed most * Special wire size selection and Teflon-insulated wire sleeves provide exact impedance matching and superb insulation, unlike common Thermaleze wire * Typical insertion loss is less than 0.2 dB * Power handling on HF is 3 kW CW and 5 kW SSB on single core models, 5 kW CW and 7 kW SSB on dual core models * May be used to 54 MHz with reduced ratings * Gasketed SO-239 connectors are silver plated and have Teflon insulation * Sealed in a weatherproof 4 in. x 4 in. x 2 in. NEMA box * Stainless steel hardware Note: Polarity markings on baluns are used for matching phase on balanced antennas when stacking beams for a phased array. Also, the positive terminal should be connected to a vertical element or Inverted-L and the negative terminal goes to the radials. For most regular applications on one antenna, including beams, dipoles and most wire antennas, balun polarity doesn't matter. The best Amateur Radio baluns in the world are from DX Engineering. That includes COMTEK Jerry Sevick W2FMI Series Current Baluns!
( 10 )
$104.99
$68.24