Principle of operation:
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.
Further the wire is usually outdoors, the tuner sets in the shack, but the wire cannot be connected to the tuner with a coax feed… Here a wire tuner like the SGC products will help – at a price!. But there is a more economic alternative.
The MTFT (Magnetic Balun) is a resistance transformer wit ha ratio of 1:10. 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. The MTFT 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.
F6JSZ installed a 20m long windom, fed with the MTFT at one third from the end, 20m coax to the rig. He writes in french “CQ” that he had a SWR better then 1.5:1 on all amateur bands and didn’t require a tuner.
But the MTFT cannot only be used with a wire but with any metallic object – water pipes, rain pipes or CB antennas (remove matching elements of the antenna before use). The MTFT is an excellent tool for the experimental amateur…
Of course the MTFT can be used for transmission, max. power load is 100W PEP.
For shortwave listeners the MTFT is an ideal accessory: a simple wire connected to the world band receiver is very badly matched, resulting in only mediocre efficiency. With the MTFT the match is greatly improved. An additional matching unit is not required.
Model 11370 is not weatherproof, use additional cover when using outdoors.
HyEndFed 5 band for 80,40, 20, 15, 10 meter band
HyEndFed 5 band for 80,40, 20, (15) and 10 meter.
Max. Power : 200 watt PEP.
Length : 23 meter.
Enclosure : Polycarbonate IP67, 100% UV resistant.
SO239 Connector : Silverplated.
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