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> affordable quality 1:1 balun 1.5 to 35 mhz #1113
affordable quality 1:1 balun 1.5 to 35 mhz #1113
This is one of Dr. Jerry Sevick's (W2FMI) most popular designs. I have adapted his design using an enclosure that allows easy installation with 1/2 wave dipoles or, by using the model with studs, for mast mounting to feed yagis. Be sure to indicate which model you prefer when you purchase.
For additional information on this design, please visit the Manufacturer's Website.
All of the baluns are hand made, hand wound one at a time utilizing the best available components for the power class. Any other balun of comparable quality will cost between $80 and $100 on the web. They may look simple but the right components are expensive and hard to find even before attempting to wind one.
This is a current balun and has the widest operating frequency range, lowest core stress and provides the best overall balance of any balun for given cost, size, and weight. This balun is the best type to balance currents on each side of a 1/2 wave dipole or the driven element of a yagi while providing the perfect transition from a balanced antenna to unbalanced coax feedline.
Installing this balun will not affect antenna matching unless the feedline is acting as part of the antenna. This is, of course, not a desirable situation and installing this balun will correct the problem if one exists with the antenna. In beam installations, using a 1:1 balun in series with the antenna s feed system can substantially improve the antenna s front-to-back and front-to-side ratios. It does this by providing the antenna's driven elements with balanced current at the feedpoint and by preventing the feedline from acting as part of the antenna.
It is a seldom appreciated fact that feedlines, which are not adequately decoupled, can act as efficient vertical antennas degrading an otherwise excellent radiation pattern. The addition of a 1:1 balun can significantly reduce feedline radiation and dramatically decrease RFI and TVI. Beam antennas especially benefit from improved balanced drive and superior feedline isolation, but even simple dipoles benefit from properly selected and installed 1:1 current baluns. Receiver noise may also be reduced by eliminating signal pickup by the coax shield.
New mix toroid with low permability allows broad frequency coverage. Toroid is also coated for durablity.
This balun has significantly higher common-mode impedance and larger effective core area than other similar designs. It is much more effective than types with ferrite rods, ferrite beads or air wound coax baluns.
Windings are Thermaleze wire with a minimum of 2000v breakdown voltage each. This is NOT the less expensive enameled wire like many of my competitors use. It may appear similar but both windings are coated with an expensive Polymide covering. I also wrap one winding in an additional layer of Polyimide tape to ensure a uniform winding impedence of 50 ohms. When combined with the Polyimide tape, total breakdown voltage is increased to over 7500 volts.
Typical insertion loss is less than 0.2 dB
SO-239 connectors are silver plated with teflon insulation.
All hardware is stainless steel.
N connectors, top eyebolt hanger and mounting options are available.
Very high efficiency. Will not heat up or saturate like the typical cheap current baluns using ferrite bar,beaded or open air wound coax.
All Baluns are sealed in weatherproof 4" X 4" X 2" Nema Box which makes an excellent outdoor enclosure.
This balun will handle continuous power of 3kw or 6kw intermittent and tolerate high SWR for extended periods.
It will not heat up at rated power, extended duty cycles or stressing load conditions.
It must be pointed out that a 1:1 balun should never be used on the second harmonic of a half-wave center-fed dipole (like an 80 meter dipole being used on 40 meters). The impedance can be as great as 10,000 ohms creating very high voltages which can bring about voltage breakdown and/or excessive heating.
Also, please note that although this balun will tolerate very high SWR, efficiency drops markedly if your SWR is 3:1 or above. At 4:1 it is down by approximately 30%
