Solid State Shortwave Receivers For Beginners - The Listeners Guide

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CHAPTER 5 - Amateur Band Receiver A.M. Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 C.W. Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 80 Metre Direct Conversion Receiver . . . . . . . . . . . . . . . . . . . . . . . 75 Using the Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 CHAPTER 6 - Ancillary Equipment R.F. Amplifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Tuned R.F. Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 Morse Practise Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 Calibration Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Using the Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Special Notes for Overseas Readers . . . . . . . . . . . . . . . . . . . . . . . . 92
CHAPTER 1 There is a strange fascination in listening to a broadcast that eminated from a-station some thousands of miles away, and this has helped to make short wave listening one of the most popular and interesting branches of electronics. Although most people interested in S.W. reception have aspirations of owning a complicated communications receiver, most start with a far less extravigant set, and almost invariably one that is home constructed. Fortunately, even using a simple receiver it is possible to receive transmissions from the other side of the world, and usually a greater sense of achievement is experienced when one receives a distant station using a simple home made set, rather than when one has used a sophisticated commercially produced receiver. Several simple S.W. receiver circuits are described in this book, and these will all give a fairly high level of performance despite the fact that relatively few components are employed in each case. There is no one simple design that will suit all S.W. listeners requirements, and it is because of this that a number of designs have been included. For instance, the Direct Conversion Receiver provides an excellent introduction to amateur band reception if the constructor has space for a good aerial and earth system and requires a fixed installation. On the other hand it is completely useless if the enthusiast is primarily interested in the broadcast bands or in a portable unit that does not require a long aerial and an earth connection. Prospective constructors are therefore advised to study the various designs and choose for construction only those that really suit their requirements. If there is no preference for either broadcast or amateur bands reception initially, then one of the general purpose circuits would probably be most suitable to start off with. However, most short wave listeners specialise in one type of reception eventually. Frequency Spectrum The S.W. frequency spectrum extends from about 1.7 to 30 MHZ, and this is divided into areas which are designated for specific purposes. Those that are of primary interest to the S.W. listener are the six amateur bands and the twelve commercial broadcast bands. Although one can simply build a receiver and then occasionally tune around the dial to see what can be picked-up, it is a great advantage to have a certain amount of knowledge about the various bands and their characteristics. Armed with this knowledge the S.W. listener stands 7
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Page 5: CONTENTS Page CHAPTER 1 Frequency S
Page 9 and 10: Propagation The reasons for the ama
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The gain of the I.C. is fixed at ap
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Like MOSFETS, CMOS I.C.s can be dam
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CHAPTER 4 Portable Receivers One mi
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Normally the telescopic aerial shou
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Components List for Fig.26 Resistor
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A.M. Signal It will be helpful to f
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As should be apparent by now, if th
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Components List for Fig.29 Resistor
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the mains earth (regardless of whet
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Components List for Fig.30 R1 3.3k
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Components List for Fig.32 R1 3.3k
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Apart from increasing the sensitivi
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Components List for Fig.36 R1 390 o
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prevent the oscillator from operati
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BERNARDS No 222 Solid State Short W
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Solid State Shortwave Receivers For Beginners - The Listeners Guide

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