Overview

CG Antennas BL-49 Unun

CG Antennas BL-49 Unun, also referred to as a 49:1 Balun, is an outdoor HF antenna feedpoint transformer. This high ratio device is particularly suitable for building an End Fed Half Wave, or EFHW antenna. Available as part number CGA-11365-49 from DX Engineering, this 49:1 Unun is built with heavy gauge wire and a large toroidal ferrite core which handles up to 600W PEP over the entire range from 1.8 to 30 MHz. The waterproof case is high strength plastic with a special valve to drain off unavoidable condensation while preventing insects from entering and nesting. A stainless steel eye hook at the top of the Unun provides an attachment point for a support rope to handle the weight of the Unun, antenna wire, and coax. Also on top is a stainless steel stud and wing nut for the antenna wire and another is on the bottom, next to a SO-239, for an optional counterpoise wire or ground connection.

End-fed half-wave antennas (EFHW) are very popular because they are easy to hang in limited space installations while achieving multi-band functionality with a transceiver built-in tuner or an external wide range tuner. In many cases the use of a BL-49 Unun with a specific monoband wire length can achieve low or reasonable SWR on many harmonically related Amateur bands. The radiation pattern of an EFHW antenna is similar to that of a dipole and the 49:1 Unun adapts to different end-fed wire configurations; the antenna wire may be suspended straight and parallel to the ground, or angled as an inverted-V or inverted-L, or run diagonally as a sloper wire, with the BL-49 Unun feedpoint located anywhere from a few feet above the ground hanging high from a support. Experimentation is encouraged with this very adaptable and forgiving feedpoint method, where the position of the wire in relation to the ground or any metal having the greatest effect on the efficiency and the pattern of the EFHW wire antenna. See antenna texts and web forums for wire lengths known to provide the best results, such as 60-70 ft. for 80-10 meters.

CG Antennas BL-49 Unun Specifications:

Frequency Range: 1.8 - 30 MHz, antenna tuner required.
Transformer Ratio: 49:1
Feedline Impedance (Ω): 50 Ohm
Max. Power: 600W SSB
Connector: SO-239 – UHF female
Size (WHD): 3.582 x 5.984 x 2.165 in. (91 x 152 x 55 mm)
Weight : 1.15 lbs. (520 g)

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