The MFJ-933 Small High-Efficiency Loop Tuner, Jr. is a versatile device designed for amateur radio enthusiasts, allowing operation across a frequency range of 5.3 to 29.7 MHz with a power output of up to 150 Watts. This tuner features a detachable mount for a PVC Cross, making it compatible with the MFJ-57B or MFJ-58B PVC Cross Loop Antenna Kits. These kits enable users to create a compact, self-contained antenna system that requires no ground, radials, or counterpoises. Users can quickly transform their setup into a high-efficiency multi-band transmitting loop antenna by simply draping a wire around a bookcase and connecting both ends to the tuner.

The MFJ-933 supports various loop shapes, including circles, squares, and rectangles, with a quarter wavelength wire shaped like a circle, yielding the best efficiency. The performance of a fixed wire length typically covers a frequency range of about 1.5 to 1, depending on the wire length, loop shape, and surrounding environment. Users have reported excellent results with this small loop antenna, known for its ability to produce low-angle DX signals that can compete with full-size dipoles. Additionally, its design minimizes static interference, making it an ideal choice for quiet reception during adverse weather conditions.

This tuner is particularly well-suited for those in antenna-restricted environments, such as apartments or hotel rooms, and is easily portable for use during trips or camping. With its easy-carry handle and compact dimensions of 6 ¼ W x 9 ½ D x 5 ¼ H, the MFJ-933 can be set up and operational in minutes, providing users with a reliable and efficient antenna solution wherever they go. Whether for casual use or serious DX expeditions, this tuner offers a practical and effective way to enhance amateur radio communication.