CTMB Transmitting 100W Magnetic Balun 0.1-50MHz

0.1-50MHz Magnetic Balun

Usual internal tuners or external tuner only have a limited impedance range. The matching of a short wire (short in comparison to the wavelength) with it's high impedance is usually not possible

Also the wire is usually outdoors, the tuner sits in the shack, but the wire cannot be connectied to the tuner with a coax feed

The is a resistance transformer with a ratio of 1:9. It reduces the extremely high impedance of a short wire to a range which can be matched with a normal tuner. The balun must be used right at the antenna wire, don't use coax to feed the wire. This magnetic balun is then connected with a coax to the tuner, the SWR on this line is usually below 3:1, losses through resonant waves are low

The required wire length should be at least 6m. Ground connection is good, connect ground with a clamp to the ground of the PL connector, not to the insulated case. If no ground can be used at the balun at least the transceiver should be grounded. If necessary use a common mode filter right below the balun. Instead of a ground connection a counterpoise can be used

This balun cannot only be used with a wire but with any metallic object - water pipes, rain pipes or CB antennas (remove matching elemens of the antenna before use) and is an excellent tool for the experimental amateur

Please note: max power is 100W PEP

For shortwave listeners balun is an ideal accessory: a simple wire connected to the world band receiver is very badly matched, resulting in only mediocre efficiency. With this balun the match is greatly improved. An additional matching unit is not required