Solid State Shortwave Receivers For Beginners - The Listeners Guide

ted it would look something like the graph shown in Fig.10(a). The peak
occurs at the resonant frequency of the tuned circuit, and the response
only falls away gradually either side qf this. As a result, the receiver has
only a very limited degree of selectivity, and when a transmission is
present within a few tens of KHZ of the desired one, both signals will
fall within the receiver’s passband, and it will not be possible to tune to
only one or other of them.
Regeneration will boost signals at or near the centre of the
receiver’s response by a far larger amount than it will boost signals
towards the edges of the response. It does this in just the same way as it
boosted positive input signals more than negative ones. This gives the
receiver a passband something like that shown in Fig.10(b). The ‘bandwidth’
as it is termed, is greatly reduced, and the receiver is capable of
accepting only one of two closely spaced signals.
This feature is very important for any S.W. receiver, because a
large number of S.W. stations tend to be crammed into each band, and a
sensitive receiver with poor selectivity would simply receive a jumble
of signals and would not be able to produce a coherent output.
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