This Isolation balun is very similar to the model 1115d with one key exception. The material utilized for the 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.
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.
Click to Enlarge
Tests run utilizing AIM-4170uhf Network Analyzer and a precision non-inductive 50 ohm load
- Custom mix toroids from Fair-Rite Products allows broad frequency coverage while maximizing performance on the lower Amateur bands. Toroids have a special coating applied for all weather protection and added durability.
- This Isolation 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 beads, ferrite bars or air wound coax.
- Windings are Mil Spec 50 ohm coax rated 19kW @ 1MHz and 9kW @ 10 Mhz. Silver flashed braid and center conductor. Solid Teflon dielectric.
- Typical insertion loss is less than 0.2 dB
- Power handling of 5kW continuous - 10kW intermittent up to 31 MHz.
- SO-239 connectors are silver plated with teflon insulation.
- All hardware is stainless steel.
- N connectors and Alternate mounting options are available in Accessories.
- Very high efficiency. Will not heat up or saturate like many of the typical "feedline choke" baluns.
- Balun is built installed in weatherproof 4" X 4" X 2" Nema Box which makes an excellent outdoor weatherproof enclosure.
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 10,000 ohms 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.
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.
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