This walkie-talkie is a dedicated model with a transmission frequency of 49.8MHz. It is relatively easy to assemble, with a high assembly success rate. The maximum communication distance is 100 meters. It has advantages such as loud sound and good sound quality, making it suitable for electronic enthusiasts with a certain electronic foundation and electronic training installation in vocational and technical schools.

Transistor Q1, coupled adjustable inductor coil T1, and capacitors C4 and C2 form an oscillation circuit, generating a carrier signal with a frequency of approximately 49.8MHz. Q2, Q3, Q4, Q5 and related resistors and capacitors form a low-frequency amplifier circuit. Speaker SPK1 also serves as a microphone.

When the circuit is in the receiving state, set the receive/transmit switch to the "Receive" position (the default state is receive). The signal from antenna ANT1 is matched to the detection circuit through the matching network composed of capacitor C4, primary winding of inductor T1, and inductor L1 for detection. The detected audio signal is coupled to the input end of the low-frequency amplifier through the center tap of the secondary winding of T1. After amplification, it is coupled by capacitor C17 to drive speaker SPK1 to produce sound.

When the circuit is in the transmitting state, set the S2 receive/transmit switch to the "Transmit" position. The speaker converts voice into an electrical signal, which is coupled by capacitor C17 to Q2, Q3, Q4, Q5 and related resistors and capacitors for low-frequency amplification. Then, the signal is added to oscillator tube Q1 through the center tap of the coupled adjustable inductor for signal modulation. The bc junction capacitance of this tube changes with the change of the voice signal, and this bc junction capacitance is connected in parallel with the bc junction capacitance of T1. Therefore, the oscillation frequency changes with the frequency of the voice signal, realizing the modulation function. The modulated wave is transmitted from T1 and L1 through the antenna.

After receiving the kit, first read the instruction manual carefully. Place all components in a container. Resistors, capacitors and other devices are very small, so identify their parameters carefully to prevent loss. When holding the circuit board by hand, hold the edge, not the surface, to prevent the circuit board from oxidizing due to dust on the hands.

All devices are inserted vertically, close to the circuit board, and not too high. Pay attention to the polarity when inserting electrolytic capacitors and transistors. Do not break the welded devices; place them vertically. The jumper J1 on the circuit board is replaced by the metal wire cut off after welding the resistor. In addition, a metal wire is needed to connect the upper end of the toggle switch to the (SW1) position on the circuit board. There are 6 wires in the kit, which are connected to the circuit in the following ways:

Rotate the black antenna sleeve onto the spring antenna, fix the lug and the spring antenna in the plastic front shell with screws, and weld the wire to the L1 position on the circuit board.

After welding two kits, carefully check for no errors, then connect a 9V stacked battery. Rotate the toggle switch knob to power on the circuit. If the reset button is not pressed, the circuit is in the "receive" state, and the speaker converts "electricity" into "sound", and a "hissing" sound can be heard. Press the reset button of the other kit to make it work in the "transmit" state. At this time, the speaker converts "sound" into "electricity". Bring the antennas of the two walkie-talkies close to each other in parallel, and slightly adjust the magnetic core of the adjustable inductor T1 with a non-inductive driver to maximize the "beeping" noise of the receiver, that is, the transmitting and receiving frequencies of the two are consistent.

Then, the two kits are adjusted in the same way to fine-tune the magnetic core of the adjustable inductor T1 to ensure that their transmitting and receiving frequencies are consistent. This process needs to be fine-tuned several times (including testing at a distance) to ensure the longest communication distance and the clearest sound between the two kits.

After successful debugging, install the "toggle switch plastic knob" and "reset switch plastic knob", fix the circuit board in the front shell with 2 screws, tidy up the wires, and fix the front and rear covers with 5 screws.

When in use, open the battery cover, install a 9V battery, and rotate the toggle switch knob to power on the circuit. Normally, the circuit is in the "receive" state. Press the reset button, and the circuit is in the "transmit" state. If there is no "hissing" sound when powered on after installation, carefully check whether there are faults such as wrong welding or short circuit in the power cord, speaker wire, components, etc. The inspection must be careful.