### Purpose

• Studying the effect of load impedance on the transmitted signal.
• Studying the principle of transmit by amplitude modulation.

### Required equipment

1. Dual powers supply.
2. Oscilloscope.
3. VOM or DMM.
4. Frequency counter.
5. Radio frequency oscillator unit, radio frequencies buffer amplifier unit, radio frequency power amplifier unit, and audio modulator unit (D64).

### Procedure

Part one: Transmit using generate radio signals and amplifier it.
1- Test the (D216, D215, D214) boards. Make sure that the pieces in the correct places, and in the same value on each Circuit.

2- Connect the circuit as shown in fig.

3- Adjust the power supply to give (20) V, ask the Supervisor to see the connections.

4- Adjust the radio signal generator unit D214 to 1.6Mhz, After turn off its output from buffer amplifier circuit D215, by changing the capacitance value CV1, use the frequency counter to adjust the radio frequency oscillator to 1.6Mhz.

Plane the output signals and record the voltage value.

5- Tune the radio frequency buffer amplifier unit to the nearest frequency for the last frequency 1.6Mhz.

6- Tune the radio signal amplifier unit to have 1.6Mhz.

7- Change the value of capacitance CV4, CV3 in power amplifier unit to have max. Possible light for damy load lamp by adjusting buffers amplifier unit.

8- Connect rms. voltmeter on power amplifier unit output and record the value.
V=33V.

9- Use resistance box (1M) to connect it on power amplifier output d216, keep the frequency of power amplifier on 1.6 MHz, then fill the following table:

10- Turn off the power and resistance box from the circuit.

Part two: Capacitance-modulating transmitter.

1- Connect the circuit shown in fig.

2- Adjust the dual power supply to 20V, one to supply the radio frequency power amplifier, and the other to supply audio power amplifier unit d64.

3- Connect the signal generator to the input of audio power amplifier unit D64 after adjusting It to 400hz and 4V(p-p).

4- Connect the leads of the jack wire to the output of d64, and the jack to the (Jm) connection on the R.F power board.

5- Ask the supervisor to see the connection, and then turn the power on.

6- Attenuate the circuit until the distortion Load lamp light to the maximum Light.

7- Change the frequency of the audio signal generator from (400,1k, 2k, 15k) Hz receptively. After connecting the oscilloscope on the output of R.F power, then observe the change of the signal.

8- Change the voltage of the signal generator from (4-5, 7, 8, 10) Vp-p receptively, then notices the change of the output signal.

9- If possible, try to hear the signal using the radio, then change the frequency, and notice the change in voice in the receiver.