41-72MHz micro-receiver ( MC3362 )

  
This receiver weighs about 6 g, used in 41 and 72 MHz, met a great success with readers of the magazine. The RX22 is the subject of these lines is improved RX20. Adding a preamp-HF improving sensitivity. Establishment of an automatic gain control of this amp. Integrated voltage regulator. Power Connectors and embedded servos. Using a MC3362DW much easier to find. We therefore returned to the MC13156 MC3362 because is very difficult to find and we seemed a bit risky handling fragile. The MC3362 is actually expected to double the frequency change but here we use simple changer.
41-72MHz micro-receiver ( MC3362 ) - schematic

The FET T1 is the HF amplifier. The signal pre-selected by L1 is injected in the first changer of 3362. Associated with the internal oscillator driven Qz, it provides the 455 kHz on the stud 19. Filtering by F1 and reinjection of 17 in the second changer, who here does not change anything because we do work as an amplifier by neutralization of the second local oscillator. Amplified output of 455 kHz to 5. Second filter F2. Reinjection into 7 in the logarithmic amplifier internally. Finally the FM demodulation quadrature using L3 for modulating the signal output 13 (BM test). This AF signal is then applied to the input of a comparator 14 whose output 15 provides the sequence formatting (SRX) and thus usable by the decoder. The logarithmic amplifier also delivers a current proportional to the collected field. (RSSI) The current from 10 is amplified by T2 and T3. It tends to block the supply of T1. Strong signal on the voltage on R2 is zero and T1 operates as an attenuator. Low signal on T1 and T3 leads amplifies. Dynamics of CAG is about 20 dB (factor of 1 to 100). INDOOR a dedicated receiver, this feature seems very important and that's why we wanted to include it. In fact, modelers use to the flight room issuers that are so typical way too powerful. If you're flying alone, it's perfect, but several potential interference by intermodulation are great, as this is a high level that it occurs. In fact, not only requires...



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