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Science Fair
ELECTRONIC PROJECT KIT #28-110
THREE TRANSISTOR SHORT WAVE RADIO
The air is literally full of radio signals from practically every country in the world. These
"short wave" signals are propagated through space and refracted back to earth by the
ionosphere to points many miles from the transmitter source. As a result, communications
services, international broadcasters, radio amateurs, and others depend on this "refraction" and
return to earth of short wave signals for long distance communications around the globe. Still, it
is difficult to believe that you will be receiving signals from far off places with only a three
transistor radio. A regenerative high gain detector with two stages of equally high gain audio
amplification provides enough audio drive for either a crystal earphone or any audio power
amplifier. Have fun "DX-ing" – distancing around the world!
Entire Contents Copyrighted 1968 by Radio Shack,
PRICE: 50
INSTRUCTION MANUAL
T
A Tandy Corp, Co. Printed in U.S.A
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TM
₵
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Summary of Contents for Science Fair 28-110
- Page 1 PRICE: 50 ₵ INSTRUCTION MANUAL ELECTRONIC PROJECT KIT #28-110 THREE TRANSISTOR SHORT WAVE RADIO The air is literally full of radio signals from practically every country in the world. These “short wave” signals are propagated through space and refracted back to earth by the ionosphere to points many miles from the transmitter source.
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Page 2: Top View
FIG. 1 – PICTORIAL DIAGRAM TOP VIEW 9V Battery ANT GND VOLUME REGEN TUNE PARTS LIST Quantity Identification Desc Quantity Identification Desc Transistor NPN (2N3904) .047uF Multilayer Capacitor Transistor PNP (2N3906) Q2, Q3 .1uF Mylar Capacitor 33K Resistor 1/4W 5% R1, R5 10uF Electrolytic Capacitor 1K Resistor 1/4W 5%... - Page 3 STEP-BY-STEP WIRING AND ASSEMBLY DIRECTIONS Be sure to carefully follow all the directions. Do one step at a time and then check off the step in the box provided. Before beginning, read over the enclosed page labeled “Construction Hints”. The step by step instructions indicate a soldering requirement; however, these connections can be made by firmly twisting joining wires together.
- Page 4 14. ( ) Remove 1-1/2” insulation from one end of a 2- 2.2K resistor R6. Connect the POSITIVE lead of C7 to 1/2” piece of wire and ¼” insulation from the other end. resistor R6 as shown in Fig 1 and solder all leads and Insert the long bare end of the wire into the perfboard wires together.
- Page 5 31. ( ) Insert the .01uF disk capacitor C6 into the 44. ( ) Insert 100K resistor R4 into the perfboard. Solder perfboard and bend the leads out slightly to keep the capacitor C4 to one end of resistor R4 as shown in Fig 1. capacitor in place.
- Page 6 The completed coil should look like the coil in the drawing. can be used as your television antenna, citizens band Wrap the coil with clear tape to prevent it from springing antenna, or even the metal dial stop of your telephone. apart.
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Page 7: Power Supply
AC-DC power supply kit #28-104. to use additional amplification. Ideal for the purpose is the It supplies either 6 or 9 volts DC for most of the Science Fair Science Fair OTL Amplifier #28-106 and the Science Fair Kits as well as most transistor radios, tape recorders, and Extension Speaker #28-123.