Solid State Shortwave Receivers For Beginners - The Listeners Guide

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
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