A 27 MHz amplitude-modulated transmitter with an output power of at least 350 mW at a 10-volt supply. The modulator is built on a 2sk3919 transistor, the oscillator on an S9018, and the power amplifier on an S8050.
Winding L1 contains 11 turns of wire with a diameter of 0.3 mm, which are wound on a mandrel with a diameter of 3.5 mm. Winding L2 contains 4 turns of the same wire and is wound between the turns of L1.
A ferrite rod must be inserted inside the windings.
You can take ferrite from a choke or sometimes a ferrite tube is put on a wire
Checking the oscillator. Connect a non-inductive 50-ohm resistor to the terminals of winding L2. Measure the signal on the resistor using an oscilloscope. The signal level will be at least 1.2 volts.
It is necessary to measure at a supply voltage of 7 volts.
Connect the power amplifier to the generator. Connect a 50-ohm resistor instead of the antenna. Apply 7 volts of power. The signal level should be at least 11-12 volts. The output power will be approximately 360 mW. If the signal level is lower, swap the terminals of the L2 winding. The L4 winding contains 9 turns of 0.3 mm wire wound on a 3 mm diameter mandrel.
Connect the modulator and apply an audio signal to its input. Increase the supply voltage to 10 volts. The signal amplitude at the transmitter or resistor output is approximately 12 volts. The S8050 and 2SK3919 transistors should be heated. Instead of the 50 ohm resistor, connect an antenna with a 50 ohm impedance.
What you need to pay attention to. Different quartz resonators may produce different signal levels from the oscillator. If the signal level is lower, try decreasing the resistance of resistor R3 or try changing the number of turns of L1. It is advisable to install the S8050 transistor on a heat sink.
Комментарии
Отправить комментарий