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SDR Receivers for VHF/UHF bands All published designs and materials are free for personal and non commercial use. Other use for commercial purpose are not allowed without permission of the author. HF/VHF/UHF SDR receivers with LO at receiving frequency Many HAM like to try new SDR technique at higher VHF/UHF frequencies. This task direct receiving is not so easy except to use standard super-heterodyne RX with HF IF where we can use new SDR technique. This design is with double balanced diode mixer as demodulator. First part describe some theoretical problems and I publish few version HF, VHF/UHF SDR receivers without image rejection.
AR1C SDR receiver built by Jean-Michel TR8JH AR1C VHF SDR receiver built by Martin 9A3 GEAR1 VHF SDR receiver built by Dragan YU1ASHF/VHF/UHF SDR receivers with LO at receiving frequency Same HAM built my DC receivers for HF/VHF/UHF frequencies and felt some kind of disappointment because receivers are not good for crowded bands and strong local station without additional circuits preamplifiers and attenuators to prevent input mixer overload or increase sensitivity. Many builders didn't read carefully article that this realizations are DC receivers without image rejection that mean that you have every signal at 2 places. This fact complicate practical use too. Here is my new SDR AR2D 2m receiver with image rejection realized by Alexandar RX3DR who realized first prototype.
AR2D 2m SDR receiver IF for 1.2GHz built by Alexandar RX3DR.
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