Simple Valve MW Transmitter circuit 30W

Posted on May 3, 2017

The simplicity of this transmitter compared to its very high performance makes it very interesting. Its output power is about 30 W and its range under normal conditions, with proper antenna and handling, reaches 30 km. The oscillator is the PL 84 which provides enough signal to normally excite the output light. Coil L1 is the oscillation coil of the 6SA7 lamp. The RFC1 has a 2.5mH inductance and can operate at a current of 100mA. The PL 509 power lamp is used in the output stage.

Click here to download the full size of the above Circuit.

The L2 coil consists of 50 coils of 1 mm thick enamel wire, wound into a 5 cm diameter drum. RFC2 has an inductance of 29mH and can operate at 600mA.

The variable capacitors C1 and C2 have a capacity of 500 pF each, with thin sheets. Transformer T1 has a primary with a 2.5K resistor. Its power is 6W. Diode D operates at 250V and can withstand 700mA current. The input of the modulator is excited by a crystalline microphone or by any other audio source.

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