tx atv


Posted on Feb 6, 2014

This project has been developed together with some other OMs (in particular Marco IW1DGG) in our local radio club. When we started looking at a simple transmitter providing sufficient power to exice the local ATV repeater we did not find anything simple to build and with components easy to find. At that time there was on the market one transmitter


tx atv
Click here to download the full size of the above Circuit.

based on SMDs components and using a Mitsubishi hybrid power amplifier (M67715) no more available almost everywhere. Looking on internet we found a simple transmitter based on through-hole mount components only and providing 50mW RF power. It was presented at the ATV Meeting in Treviso in 2001 and you can find it here (in italian ony), on the ARI Vittorio Veneto web site. We have only slightly modified this transmitter adding a power amplifier stage based on a BFG35 (or BFG135) providing about 0. 5W output RF power, which is sufficient to operate through repeaters and to perform short distance (tens of km) direct QSOs. This is the electrical diagram of the complete circuit as we modified. You can identify the video input section with the A-V mixer in the upper-left part of the diagram, the audio section in the lower-left part of the diagram (around the TL081), the PLL and low power stage in the center of the diagram (composed by the PIC, the TSA5511, the BFW91 and the first BFR96) and the power stage on the upper-right part of the diagram (composed by the second BFR96 and the BFG135). The PCB that we have realised is based on the ARI Vittorio Veneto design and consists of a simple two layer board. All components are "big size" (no SMD) except for the RF varicap diode. Some of them have to be soldered directly on the component side, but the majority is mounted in a standard way, i. e. via through-holes soldered on the...




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