Principle of work
- Transmission part: The RF carrier signal generated by the phase-locked loop and voltage controlled oscillator (VCO) is amplified through buffering, encouraging amplification, and power amplifier to generate additional RF power. The harmonic components are suppressed through an antenna low-pass filter, and then transmitted through the antenna.
- Receiving part: The receiving part mixes the amplified signal from the future RF with the top local oscillator signal from the phase-locked loop frequency synthesizer circuit at the top mixer and generates the top intermediate frequency signal. The top intermediate frequency signal is further eliminated by a crystal filter to eliminate clutter signals in adjacent channels. The filtered top intermediate frequency signal enters the intermediate frequency processing chip and is further mixed with the second local oscillator signal to generate the second intermediate frequency signal. The second intermediate frequency signal is filtered out by a ceramic filter to remove useless stray signals, then amplified and discriminated to generate an audio signal. The audio signal enters the volume control circuit and power amplifier through circuits such as amplification, bandpass filter, and de emphasis, driving the speaker to obtain the information people need.
- Modulation signal and modulation circuit: The electrical signal that converts human speech into audio through a microphone.
- Signal processing: The CPU generates CTCSS/CDCSS signals that are amplified and adjusted to enter the voltage controlled oscillator to terminate modulation. After receiving the low-frequency signal obtained from frequency discrimination, a portion of it is filtered and shaped by amplifying and sub audio bandpass filters, and enters the CPU. It is compared with the preset value and the result is manipulated to control the output of the audio amplifier and speaker. Assuming it is the same as the preset value, open the speaker, and if it is different, close the speaker.
- There are many types of batteries used in walkie talkies, and now different walkie talkies have different batteries, generally nickel cadmium batteries and lithium batteries. The usage and capacity of batteries are also different, so it is necessary to pay more attention to battery maintenance and other conditions when using them. Currently, many users are not very satisfied with the usage of walkie talkie batteries. Due to various reasons, To stop the modification of the walkie talkie battery and other related matters, let’s introduce the modification and precautions for the walkie talkie battery below.
Modification of walkie talkie batteries
The construction of walkie talkies is very different, so here, taking TK-2207G as an example, we will explain the information about battery modification of walkie talkies. After using walkie talkies for a period of time, it will be discovered that the battery life of walkie talkies is short. Therefore, the innovation of walkie talkie batteries is also a necessary task, and the cost of renovation is not high, and the required materials are not difficult to find.
Firstly, there is a requirement for two normal mobile phone batteries, with lithium battery cells of the SL-703W-703465 model. The best charging voltage is 4.2V, and the capacity should not be too large, only 1600mAh. Such batteries can be found in general mobile phone stores or some repair shops, and two are enough.
The walkie talkie is equipped with a regular battery, which usually requires 6 rechargeable 5th batteries for operation. The batteries are very useless, but after modification, the two prepared mobile phone batteries will be connected in series, and diodes and varistors will be added to stop releasing and charging the battery.
The process is very simple. Just open the outer shell of the walkie talkie, remove the original battery, connect the phone battery in series, install it into the walkie talkie, and stick it firmly with glue. That’s it.
Precautions for modifying walkie talkie batteries
If the purchased battery is a new one, it should be fully charged three times before discontinuing use. Moreover, after the modification is completed, it should be tested first to ensure that there is no leakage or power connection before discontinuing work, charging, and other uses.
Influencing factors
System parameter
1) The stronger the output power of the transmitter, the larger the masking range of the transmitted signal, and the farther the communication distance. However, the transmission power should not be too high. Excessive transmission power not only consumes electricity and affects the lifespan of power amplifier components, but also has strong disturbance, affecting the communication function of others and generating radiation pollution. Radio management agencies in various countries have clear rules regarding the transmission power of communication equipment.
2) The higher the receiving flexibility of the communication machine, the farther the communication distance will be.
Environmental factors
Environmental factors mainly include pathways, tree density, electromagnetic disturbances in the environment, buildings, weather conditions, and differences in terrain. These elements and other parameters directly affect the field strength and masking range of the signal.
After the modification of the walkie talkie battery, the usage time has greatly increased. Moreover, by fully charging the walkie talkie battery for 12 hours, it can be used for a full three days.
