ANTENTOP- 01- 2012, # 016

S- Tuner

Eugene (RZ3AE)

Credit Line: http://www.cqham.ru/ant71_34.htm

S- Tuner provides matching of asymmetrical output of a transceiver with symmetrical feeder line. Symmetrical feeder line (as usual it is two- wire ladder line or two- wire line with plastic insulation) used to feed symmetrical dipole antennas.

Lots additional stuff on S- Tuner it is possible to find from the site PA0FRI http://pa0fri.home.xs4all.nl/

Figure 1 shows schematic of the S-Tuner.

Figure 1 Schematic of the S- Tuner

Binocular transformer (made on ferrite tubes used on the monitor cable) forms symmetrical output. Variable capacitor and tap inductor provide matching two- wire line feeder with transmitter. Figure 2 shows design of the S- Tuner.

Variable capacitor used at the tuner has capacity 12x520- pF. At the lower HF-Bands it may be need to connect to bridge to the variable capacitor a fixed capacitor on 500- pF or 1000- pF. It is possible to use a two or four section variable capacitor from an old tube receiver. At the case rotors should be connected to binocular transformer stator should be connected to the "ground." Such capacitor works fine up to 100- Wtts.

At the S-Tuner it is used a tap- inductor on ferrite connected in serial with air- winded inductor. Air winded inductor is used at upper HF- Bands. The air winded inductor contained 4 turns of copper wire in diameter 1.3- mm (16- AWG). Inductor is coiled on a form in diameter 10- mm. Then it is stretched to 6-10 millimeter (should check by experimental) in length. Tap inductor is coiled on ferrite ring Amidon T200-2. The inductor has inductance in 40- microHenry. Figure 3 shows the inductor. Inductor has 15 taps. Tap # 1, 2, 3 made from each turn. Tap # 4, 6 made from each second turn. Tap # 7, 8 made from each third turn. Tap # 9 from fourth turn. Then taps spaced evenly among the rest taps. It is possible to use at the S- Tuner almost any tapped inductor with overall inductance up to 34- microHenry.

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