Some interesting Projects


Posted on Feb 7, 2014

A design for a synthesised ATV transmitter covering the 13cm band and beyond up to about 2. 6 GHz. This transmitter has been designed for optimum video performance and can achieve a broadcast quality signal when received with a professional TV microwave receiver. The design is based around a commercial voltage controlled oscillator (VCO) wh


Some interesting Projects
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ich forms the heart of the transmitter. This unit allows for the complete absence of RF alignment requirements and also aids in the construction and reproducibility of the design. The transmitter also makes use of a commercial power amplifier module made by Down East Microwave producing about 1. 6W. The transmitter exciter could be operated on it`s own if required and produces about 50 mW. The microwave signal is initially generated by a VCO made by Z-comm. This company produces a wide range of VCO products and so the one chosen meets our requirements very well. The module tunes about 2. 2-2. 7 Ghz and provides an output of about +10 dBm. The unit can almost be considered a little TV transmitter in it`s own right. The tuning voltage input spans about 1-10V and has very low capacitance and so excepts high frequency video modulation with ease. The VCO is very stable as it was originally designed for narrow band applications, it also simplifies the design of the transmitter considerably. A colleague of mine has built a miniature TV transmitter using one of these units and an amplifier which measures just a couple of inches square. The VCO feeds two destinations via a 3 dB attenuator and a resistive splitter. Z-comm recommend this approach as it improves the isolation of the VCO and prevents it from "pulling" with changing load. The splitter is made up of three 18R resistors and so provides further loss and hence isolation. One...




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