Hüsnü Köktürk TA6CAA yozgat LW MW DIRECT AM RADIO RECEIVER alıcı devresi

LW DIRECT AM RADIO RECEIVER

By Hüsnü Köktürk - TB6CAA

The device is not a toy. It is a serious receiver, not regenerative nor reflex type, only has one tuned three stages rf amplifier type direct receiver. The two stage is enough for receiving LW but the three is good. Perhaps the four stages is best but I did not fell need for it. For MW band quadrupled is advice. SW needs more stages but the selectivity will be lacking at that frequency. Selectivity is enough for LW band, if desired more selectivity some number of turn removed from L2 coil. For 12 cm ferrite rod antenna the turn number is 16-30 is ideal, L1 =180-200 turn. The principle is more turns and less capacitors. Be carefull, the ferrite rod antenna on the rf stages reduces or increases the sensititivity of the receiver. Also makes the sensitivity to zero easily, or opposite of this makes harmful distorsion. So The ferrite must be far from rf stage and loudspeaker, or some suply cord. The best is to make plug play while listening.

Adding audio amplifier is not much easy although the receiver accepts many kind of amplifier, but our advice is to use an old type germanium Ac187-Ac188 complementary four transistors amplifier. The dedection diodes must be germanium types low-power rf like AA112- 121.etc. I couldn’t read diod numbers my own. For rf stages accepts many kind of transistors. I saw that some BC type transistors gives more selectivity than others. Q-1-2-3, 9018 Japan, the other 2x BC308b is audio amplifer and some dedections transistors. It is possible to add a rf stage made fet like bf244 in front of the receiver so, than, no needs to get medium point coil The device needs less voltages if fr stages is much. For 4 stage rf 1v2 volt enough and for two stages needs much voltages. So the voltage of the receiver depens to the number of rf stages . Select the oltage between 1v2, and 2,4 . If needs less voltages put 1k5 serial resistor to + pole. The 100k pot solves this problems instead of us (sorry for poor English)

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