This is a unique design by Dr. Jerry Sevick (W2FMI) that combines a 25 ohm balun with a 1:2 unun for final transformation to 50 ohms. Used anywhere there is a need to transform 25 ohms balanced to 50 ohms unbalanced. We have eliminated a common failure point of this design by inserting one of the unun windings in Teflon tubing. Consequently this is an enhanced version of the balun used for the popular SteppIR yagis. IMPORTANT NOTE - This balun is a complex custom wind and as such is not eligible for exchange or refund except for defect in materials or workmanship.
Note: This model is also available without an enclosure to use as a replacement for a damaged SteppIR balun. Select model 1213x from above.
|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||Two stage balun/unun wound on single core.|
|Winding Material|| Hand made 25 ohm impedance coax for first stage balun.
Second stage is trifilar wound unun of heavy gauge thermaleze wire.
Center conductor of unun is inserted in Teflon tube to increase cross conductor isolation.
7000v breakdown voltage
|Power Rating|| 1.5 to 31 MHz - 3kW
All ratings based on resonant load. High SWR will reduce power handling ability.
|Useable Frequency||1.5 to 31 MHz|
|Insertion Loss||Less than 0.3db|
SO-239 connectors are gold center conductor with Teflon insulation.
|Hardware|| All Stainless Steel
Studs are 1/4 inch
| Enclosure Type
|| NEMA rated 4x marine grade junction box for outdoor installations.
Cover utilizes integral neoprene gasket for weatherproof integrity.
|Dimensions|| 4x4x2 inches for main body of unit
Dimensional Drawing of Standard Enclosure
|Additional Info|| Very high efficiency (98+%)