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Balun Designs

Model 1116d - 1-31 MHz, 5kW - Optimized for Low Frequencies


Model 1116d - 1-31 MHz, 5kW - Optimized for Low Frequencies

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Product Description

This Isolation balun is very similar to the Model 1115d with one key exception.  The material utilized for the two stacked cores is optimized for the lower HF bands and provides exceptional choking impedance at these frequencies. Over 5000 ohms of choking on 160m and over 6300 ohms on 80 and 40 meters. The 1116d even generates over 4000 ohms of choking impedance on 20 meters. 

No other design can provide this level of isolation and choking at these lower frequencies.  Note that although optimized for lower frequencies, this balun also provides very good choking at higher frequencies and can be used up through 30MHz. 

Please go to the Accessories category for additional RF connector types and mounting options.

Testing shows SWR remains below 1.05 across the entire HF band, transformation is perfectly flat, return loss is between 60-80 dbmw and choking impedance is maximized at over 6k ohms on the low HF frequencies. Please click on the graphs shown below to view the complete test results.
  choking-impedance.jpg  1116d Scan_thumb.jpg
Click to Enlarge

Tests run utilizing AIM-4170uhf Network Analyzer and a precision non-inductive 50 ohm load

Noise Reduction

While the most common advice is to improve the station's RF ground, the root of the problem is in the poor isolation of the feedline from antenna currents. If your goal is to reduce feedline radiation and improve reception by reducing noise, feedline isolation baluns are an excellent choice. Adding an additonal isolation balun at the point where the feedline exits the near field area of the antenna will substantially reduce unwanted feedline radiation and reception of EMI without the need for improved station grounding. 

***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 as great as 5,000 ohms creating very high voltages which can bring about voltage breakdown and/or excessive heating. This exception ONLY applies to COAX FED HALF WAVE DIPOLES WHEN USING A 1:1 BALUN AT THE FEEDPOINT.



  Core Material   Custom mix ferrite by Fair Rite Products optimized for low frequencies.
  Cores are coated and sealed for long term durability.
  Winding Type   Stacked dual core, coaxial wound 1:1 current balun provides larger effective core area.
  Winding Material   Mil Spec 50 ohm coax rated 19kW @ 1MHz, 9kW @ 10 MHz & 4kW @ 50 MHz.
  Silver flashed braid and center conductor with solid Teflon dielectric.
  Power Rating   1 to 35 MHz - 5kW, 10kW intermittent.
  All ratings at resonance. High SWR will reduce power handling ability.
  Useable Frequency   1 to 31 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
  Additional Info   Very high efficiency (98-99%). 
  Will not heat up or saturate at like many of the "less expensive" designs.

Installation Notes


Additional Information