Windings of Mil Spec coax allows this balun to provide a very high power rating across all HF frequencies, creates windings that have extremely uniform impedance for excellent transformation and very good choking impedance. By utilizing one of our mounts in Accessories, the balun can be securely installed on a mast, boom or where ever you need it.
Sometimes called a choke balun or common mode choke, this 1:1 ratio balun is the best for feedline isolation. It has the widest operating frequency range, lowest core stress and provides the best overall balance of any balun for given cost, size, and weight. If you have a yagi you should be using one to balance the power to the driven elements and prevent the coax feedline from distorting your radiated pattern. If you have a vertical you should be using one to prevent the vertical element from using your coax as a radial and to decouple the feedline for reduced noise.
This balun is more than just high power. Tests show SWR is below 1.06 across the entire HF band, transformation is perfectly flat, return loss is typically 60-75 dbmw and choking impedance peaks at over 5k ohms. Please click on the graphs shown below to view the complete test results.
Tests carried out in an anechoic chamber to determine the affects of unbalance on radiation patterns of a half wave dipole (published April, 1980 in QST) show just how serious this can be and how important the function of the balun is in achieving predictable patterns. Notice how the pattern is distorted when the feedline is not being isolated with a balun.
Regardless of the antenna you're using, an isolation balun can provide numerous advantages:
Preventing unwanted RFI by eliminating feedline common mode currents and radiation.
All power goes to the antenna, improving efficiency.
Power is balanced between driven elements of antenna.
Can help overcome a less than optimal ground.
!!! One Exception !!!
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 fed with coax (like an 80 meter dipole being used on 40 meters). The impedance can be 5000 ohms or greater creating very high voltages which can bring about voltage breakdown and/or excessive heating. This exception ONLY applies to HALF WAVE CENTER FED DIPOLES WHEN USING A 1:1 BALUN AT THE FEEDPOINT and does not apply to dipoles fed with ladder line.
|Core Material|| Custom mix low permeability ferrite by Fair Rite Products for maximum bandwidth.
Large 2.4 inch core is coated and sealed for long term durability.
|Winding Type||Single core, coaxial wound 1:1 current balun|
|Winding Material|| Mil Spec 50 ohm coax rated 19kW @ 1MHz, 9kW @ 10 Mhz and 4kW @50MHz.
Silver flashed braid and center conductor with solid Teflon dielectric.
|Power Rating|| 1 to 35 MHz - 5kW, 35 to 54 MHz - 4kW.
All ratings CCW into resonant antenna.
|Useable Frequency||1 to 54 MHz|
|Insertion Loss||Less than .02db|
|Connectors|| SO-239 connectors are silver plated with Teflon insulation.
Studs and eyebolts are 1/4 inch.
Alternate connectors and Mounting Options are available in the Accessories section.
|Hardware||All Stainless Steel|
|Enclosure Type|| NEMA rated 4x marine grade junction box for outdoor installations.
Cover has neoprene gasket for weatherproof integrity.
|Dimensions|| 4x4x2 inches for main body of unit
Dimensional Drawing of Standard Enclosure
|Additional Info|| Very high efficiency.
Will not heat up or saturate at like many of the "less expensive" designs.