Solid State Shortwave Receivers For Beginners - The Listeners Guide

Components List for Fig.30
R1 3.3k
R2 680 ohms
C1 47nf plastic foil.
C2 22pf plastic foil.
L1 10mH. (Repanco CH4).
Tr1 2N3819.
S1 S.P.S.T. toggle.
Hardware.
spectrum. This is because the input and output of a common gate
stage are in phase, and any feedback due to stray circuit capacitances
is positive, and tends to inciease gain rather than diminish it.
The circuit of Fig.32 is basically the same as that of Fig.30,
except that it has been modified to use the aerial input coupling coil
of the receiver as its drain load. It will only work with receivers that
use an aerial coupling coil (which most do).
This circuit is of the positive earth type, but as it uses its own
power source, and is isolated from the receiver by its input transformer,
it can be used with both positive and negative earth receivers. In fact
any of the R.F. amplifiers described here are suitable for use with either
type of receiver.
The circuit of Fig.33 is the grounded base version of Fig.32.
Although one might think that. the tighter coupling between the -
receiver that is achieved with the circuits of Figs.32 and 33 would give
these a higher gain than the previbus two circuits, in practice this
would not appear to be the case. Their gain would seem to be
fractionally lower.
82