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  • Shipment on new orders for all Gemini amplifiers is currently January 2019, PowAbeam antennas 3-4 weeks from order.

1:1 ATU Current Balun 1-54 MHz 5kW

 

  • 1:1 ATU Current Balun
  • 1-54MHz
  • 5kW power handling
  • INsertion loss <0.2dB
  • Studs on top
  • Silver Plated SO239 connector
 

Availability: In stock

Price excl VAT: £79.95 Incl VAT: £95.94
 
OR

1:1 ATU Current Balun 1-54 MHz 5kW

The DX Shop are distributors for Balun Designs

 

 

This is a departure from the normal 1:1 isolation/choke balun and utilizes a bifilar pair designed to maximize interwinding breakdown voltage. The balun functions to transform balanced twin lead, ladder line or open wire to unbalanced coaxial feedline while providing high levels of choking impedance to stop common mode currents from entering equipment.

This balun is NOT wound with the normal 50 ohm pair, instead the design criteria is maximizing inter-conductor breakdown voltage.  Consequently, this design is intended primarily for use with multiband wire antennas such as doublets and loops where there will be a wide range of impedance values generated across the different bands and a tuner is required for the final match.  Use with resonant monoband wire antennas is not recommended.

With wire antennas being used primarily on the lower HF bands, choking impedance for this balun has been shifted to provide maximum performance on the 160m through 40m bands. However, this ferrite mix also provides excellent common mode control on the upper HF bands where high choking impedance levels are not as critical. It is best installed outdoors to minimize the chance of RF entering the operating position from the balanced feedline.

Typically this balun is utilized with a tuner that can easily match a wide set of impedance values. 

 Design Criteria

- T match antenna tuners perform quite poorly if the resistive component of load impedance is very low, even worse if there is also a high capacitive reactive component. This is a common load found in shortened dipoles fed with open wire line.

- The traditional approach is to use a 4:1 balun on such antennas, but antenna tuner loss is worse with low resistive loads.

- The need to tolerate high voltages occurs when the balun happens to be located near a differential voltage maximum.

- Generation of high choking impedance for effective reduction of common mode current.

- Balun is intended for use with an antenna tuner which will manage SWR and transformation mismatches.

- Differential insertion loss is not significant in this application, the dissipation in a current balun is primarily from the common mode current which is installation dependent and not easily predicted.

Specifications



  Core Material
  Custom mix ferrite from Fair Rite Products optimized for low frequencies.
  Cores are coated and sealed for long term durability.
  Winding Type   Stacked dual core, bifilar pair 1:1 current balun provides larger effective core.
  Winding Material   Heavy gauge Essex polyamideimide Allex 240 Winding Wire wire inserted in teflon tubes.
  Breakdown voltage in excess of 10kv
  Power Rating   1 to 31 MHz - 5kW, 8kW intermittent.  32 to 54 MHz - 3kW, 5kW intermittnet.  
  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.
  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.