Page 29 - Build Your Own Transistor Radios a Hobbyists Guide to High-Performance and Low-Powered Radio Circuits

Chapter 2

Calibration Tools and Generators for Testing

Many of the radios in this book will include adjustable inductors for
intermediate-frequency transformers and oscillator coils. Therefore, special

adjustment tools are required. This book will include not only radio projects but
also circuits that require test generators to test and verify some of the el'ectronics
theory. For example, the generators will be helpful in testing both radio-frequency
(RF) and audio-frequency amplifiers. Other test equipment, including a volt-ohm
milliampere meter, an oscilloscope, a capacitance meter, and an inductance meter,

will prove very useful for building and troubleshooting the various circuits.
Alignment Tools

The types of tools needed for the projects in this book are simple flat-blade
alignment tools. These are used instead of flat-head screwdrivers so that there is
no damage to adjustable inductors. Adjustable inductors use ferrite slugs to change
the value of the inductor. Sometimes, when a regular screw driver is used, the
ferrite si ug. can crack.

In addition, the alignment tools have thinner and wider blades than many
screwdrivers, which relieve stress on the ferrite material. These alignment tools also
have blades that are thin enough for adjustment to the trimmer or padder
capacitors in poly-varicon variable capacitors (Figure 2-1).

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FIGURE 2-1 Alignment tools.
The alignment tool in the middle of the figure below the board is suitable for
adjusting the variable inductor and the poly-varicon's trimmer capacitors at the top