The video transmitter has a very stable saw crystal controlled circuit. The power output of this transmitter is app. 80 mW / 50 peak-to-peak - modulated. The oscillator was built in a stable Colpitz configuration. After the oscillator signal is going to an RF amplifier and mixer. Antenna ?wave is attached to the board. Modulator has two transistors in video amplifier configuration with a negative TV amplitude modulation over 75 %. The complete unit has 4 transistors. The currency consumption is 36 mA/ 9 V or 42 mA / 12V. This transmitter is inverse polarity protected. An RF output transistor is Motorola MMBR 941. The complete unit was built in surface mount technology. PC board is a high quality FR? material. Video amplifier was built in a stable configuration with an open video input. For Cmos cameras for the best results an resistor 220- 270 ohms is added in serial connection to the video input. This video transmitter has excellent picture quality. The range is also over 1000 ft LOS can be obtained with a high gain antenna on the receiving end..
Since the video input of this transmitter is not DC coupled some CMOS cameras will interfere the modulation with the DC voltage (app. 2 V out). A compensation resistor 100-270 ohms is used in serial combination with video input. The other method would be the RC combination, 47 uF capacitor and a resistor 100 ohms before the input will work fine for any cameras. We have used 2.4Ghz for excellent quality of the transmitters. The give quality pictures in line of sight configuration.
wireless transmiiter general data.doc (Size: 60.5 KB / Downloads: 84)