To protect cell phone jammer being damaged by the over heat

A frequency synthesizer circuit and the reference clock oscillator, phase detector, low pass filter, VCO and divider composed of five parts. Among them, the phase detector and dividers generally integrated IF IC, the low-pass filter is generally discrete components. Phone reference clock circuit is 13MHz oscillator circuit, the oscillation frequency should be within the 13MHz_ to +100 Hz, if the baseline frequency offset is greater than 100Hz, will have no signal or the call dropped calls, in addition to the clock frequency instability to produce a frequency deviation outside , due to the clock signal through the circuit failure caused by many reasons, in addition, the AFC if the circuit or the signal of the control signal of the reference clock is not working properly, will seriously affect the stability of the reference clock, maintenance should be attention. If the voltage, current or pressure of  cell phone jammer  exceeds the specified value.
Voltage-controlled oscillator circuit should be careful to check three things: First, the power supply should be normal; PLL control voltage (usually by a foot of the IF IC output) should be normal when you start receiving circuit should be 1 - the 4Vp-p pulse output, standby mode, the waveform is not always appear, and network synchronization will arise, the waveform sparking. If there is no output, should be welded relevant circuit. The oscillation frequency of the output should be stable. Generally adopted, if the local oscillator circuit does not work, it will cause the reception field strength shows that the local oscillator circuit is not working properly, it will cause the receiving field strong display flashes frequently, and sometimes play and sometimes not playing, or a phone field strong signal disappearance of failure. The local oscillator output can only be measured with a spectrum analyzer or frequency counter to. And automatically to protect  cell phone jammer .
Logic audio circuitry is not normal. GMSK demodulation logic audio circuit when it is received RXI / Q signals RXI / Q signal simulation is converted to a digital signal; GMSK modulation will launch the digital signal converted to the TXI / Q analog signals, in addition, the logic The circuit also outputs the control signal of the whole, therefore, logic audio circuit failure will cause the phone network, logic audio circuit have been integrated, and maintenance should focus on strengthening the soldering and cleaning. Maintenance practice from the point of view, logic audio circuits phone network failure is rare. The transmitter circuit is not normal. The transmitter circuit power supply, input and output signal is only measured in the launch state. It is the centralized management of  cell phone jammer .
Therefore, the maintenance of transmitter circuit should first start transmitting circuit, so that the transmitter circuit, and then with the purpose oscilloscope, frequency counter or spectrum analyzer measurements. According to different models, repair the following four methods can be used to start the transmitter. The first method is to call 112. Call 112 simultaneously start transmitting and receiving circuit, This method is suitable to call 112 more convenient cell phone after the teardown. But the drawback is the test more difficult, it is necessary to call 112, but also to test. Very hectic. The second method is to use the test card. Motorola has a special test card. Normally, the manufacturer will produce some popular kinds and types of   cell phone jammers .