The author was taking notes in his lab while testing the receivers being described herein, and used them later to write this book. One remark about the receiver whose electrical diagram is given on Pic.3.35 was: “Works EXCELLENT”. The reader will probably ask himself: Isn’t this the aforementioned “The Best Receiver”? No, it isn’t, just remember: DE GUSTIBUS... If, however, you consider it to be “The One”, please send your vote on E-mail: tesla@drenik.net;
This device is very similar to the one being described in the previous project. The most important difference is that the LF signal exiting the ZN414 does not go to the transistor amplifier but to the power amplifier built around the LM386, which was used in some previous projects. Any other audio amplifier can be used instead, e.g. those on Pics. 3.15, 3.21 and 3.22.
With this receiver, special care should be taken regarding the voltage on pin No.1. As you did in previous project, put the potentiometer’s slider in mid-position, turn the receiver on and tune it to some station. Move the slider carefully, until you reach the optimum reception. Start changing the capacitance of the variable capacitor, covering its entire scope, to make sure that receiver works well in its entire operating range. If a problem occurs, re-position the slider again. When everything gets OK, turn the receiver off, disconnect the potentiometer, measure its resistance, and solder the resistor of such resistance on the board. The R2 resistance must be no less than 600 Ohms.
EmoticonEmoticon