Page 43 - Build Your Own Transistor Radios a Hobbyists Guide to High-Performance and Low-Powered Radio Circuits

can be used for TRF, reflex, and regenerative radios but not for superheterodyne

radios, which require two or more sections.
In the center of the figure is a two-section (two gang) variable capacitor. This
particular capacitor has an antenna section on the left side and an oscillator section
on the right side. Notice that the number of plates on the left side (antenna
section) is larger than the number of plates on the right side (oscillator section).
Not shown, but on the other side of this variable capacitor are adjusting screws for

each trimmer capacitor that are connected internally to the antenna and oscillator
sections.
Finally the variable capaCitor at the top of Figure 3-6 is a four-section capaCitor.
Two sections are used for the AM band, and the other two are used for the FM
band. Since this book is limited to AM radios, only two will be used. Counting from

left to right, section 2 is for the oscillator, and section 4 is used for the antenna of a
superheterodyne receiver. Also not shown are the trimmer capaCitor screw
adjustments on the other side of this variable capacitor.
Transistors

In terms of tranSistors, the most common lead (terminal) configuration is E, B, C
(emitter, base, collector), as shown in Figure 3-7.