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UHF indicator or wavemeter is some kind of device that measures frequencies and determines LC circuit frequecy resonance . This device does not need to radiate.
The oscillator is build with T1 and T2 (2 x BF494) and can be adjusted with C1 and Lx. The Lx coil is connected outsite of the metal box and has to be changeble handiest.
If Lx is inductively coupled with another LC coil wich has the same frequency as the wavemeter, then will extract energy from oscillator coil, this will result in a voltage reduction.
This UHF transmitter is designed for low power applications as remote for garage doors and operating systems, wireless alarm. This UHF FM transmitter with only one transistor which works on frequencies reserved to low power airwaves signaling.
Transmitters frequency is FM modulated by an audio or digital signal applied in the common point of D1 or D2, through R3. The transmitter schematic can e modified to produce AM modulation by eliminating D1, D2, R2, R3 and R6, and short circuinting A and B points.
This amplifier circuit is used to amplify TV signals in UHF range. It uses a low-noise transistor and gives 10 to 15 dB amplification in the frequency range from 400 MHz to 850 MHz.
The transistor must be shielded from the input components and in constructing this circuit, the wirings must be as short as possible. For best results, the cable must be directly soldered to the PCB. The circuit should be installed near the antenna and housed in a water proofed case.
