Description
MTFT Multi: The MTFT MULTI is a transformer with three ratios 4:1 9:1 16:1. It reduces the high impedance of a short wire to a range that can then be tuned by a common tuner. The balun must be placed directly at the connection of the wire antenna; absolutely do not use a coaxial cable to power it. The MTFT is then connected to the tuner via coaxial cable, the VSWR will be less than 3:1, and the losses will be low. The antenna length must be at least 6m. The earth connection must be good, the earth must be connected with a clamp to the earth of the PL, not to the insulated container. If no ground is available at the balun, at least the TRX must be connected to ground. If necessary, place a common mode filter before the balun. A counterweight can be used instead of the ground connection.
F6JSZ has installed a 20m windom, powered by an MTFT at a third of its length, and 20m of coaxial cable. He wrote in the French magazine “CQ” that he had an SWR better than 1.5:1 on all bands and…without a tuner…!
The MTFT can be used not only with a wire, but with any metal object, water pipes, gutters, CB antennas (in this case, remove the matching elements from the antenna before use). The MTFT is also a great tool for experimenters…
Of course, it can be used in transmission, max. power of 100W PEP.
Operating principle:
Usually internal or external tuners can work in a limited range of impedances. Coupling with a short wire (short compared to the wavelength) is not possible due to its high impedance.
Furthermore, the wire is usually external while the tuner is inside the station, and they cannot be connected to each other with coaxial cable… In these cases a tuner like the one from SGC could come in handy – but, at what price! There are cheaper alternatives.
Features / Specifications:
MTFT MULTI Magnetic balun for long wire ratios 4:1, 9:1 and 16:1
Frequency coverage: 0.1 – 50MHz
Power rating: 150W PEP
Watertight version for mast mounting. max. 60 mm
With a few meters of wire on 0.1…50 MHz QRV! Can be used with limited efficiency up to 150 MHz
Go in the air with just a few meters of line..!
(3) Taps for external use with wire MTFT-MULTI.
