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Learning Objectives: After studying this chapter, you should be able to:
• describes the process of making a six transistor radio;
• make a six transistor radio.

Material in this Cha...

Learning Objectives: After studying this chapter, you should be able to:
• describes the process of making a six transistor radio;
• make a six transistor radio.

Material in this Chapter:
A. Persian pan Tools and Materials
B. Chassis manufacture
C. Installation of components on the chassis (PCB)
D. Wiring Components at Terminals
E. Soldering
F. Testing of Circuit Results

making six transsistor radio

The manufacture of a six transistor radio or a superheterodyne radio requires several tools, namely as follows.
1. Screwdriver
2. Hacksaw
3. Hammer
4. Drill
5. Miser
6. Pliers
7. Zinc scissors
8. Vise (vise)
9. Solder the bout
10.Multitester (AVO)
11. Testpen
12.Oscilloscope (if you have one)
13. Signal injector

radio schematic of a six mw npn transistor radio receiver

What is meant by chassis is a PCB (Printed Circuit Board) which functions to put all the circuit components to be practiced.
The explanation of how to build a chassis has been discussed in the previous chapter of this book.

After the PCB is finished, all the superheterodyne radio components are installed on the PCB. In order not to encounter a lot of difficulties, components should be installed with similar groupings. For example, the first stage installs all fixed Rs, the second stage installs all ceramic capacitors, the third stage installs electrolytic capacitors, then the transformer type and so on.
The components that are installed outside the PCB are:

a) loudspeaker (LS);
b) antenna spool with fefit rod;
c) potentiometer (some are directly mounted on the PCB).

Installation of these components requires wiring, which requires connecting cables between the components and the PCB. In principle, the installation of this superheterodyne radio component is not much different from that of the previous practical components. However, in order not to encounter difficulties, it is necessary to pay attention to the following points.
1. In the installation of a fixed resistor, the value between R and R should not be confused.
2. Installation of the elco legs must not be reversed. In principle, the minimum elco capacity value is as stated on the list, so it is permissible to use the capacity value above it, but not the capacity value below it.
3. Installation of the antenna spool.

installation of the antenna spool

4. Installation of the on-off switch on the potentiometer

installation of the on off switch on the potentiometer

The negative pole of the voltage source is connected directly to the PCB, the sign (-) of the potentiometer d is connected to the positive voltage of the voltage source, and the potentiometer e is connected to the positive sign (+) on the PCB. Installation of d legs with e can be reversed.

To get a good soldering result, it is necessary to know the basics of soldering. A good soldering process will produce a small, dull and shiny solder. You learned how to solder in Grade VII.

After all the components are installed on the PCB with the soldering process, the next step is the process of testing the circuit results.

Circuit Testing Instructions

There is nothing to be afraid of when trying out the circuit. Before the circuit is tested, pay attention to the following points.
a. Re-examine the installation of all components, do not install wrong.
b. Examine the results of the soldering, so that there is no short circuit between the solder and another which should not be connected.
c. If using an adapter, be careful about attaching plugs and cables that come out.
d. Connect the LS mark on the PCB to the loudspeaker using a cable.
e. Connect a 6 volt DC voltage source to the circuit. Don't reverse the installation of the poles.
f., Open the switch on the pot, if the circuit works well on the LS you will hear a sound or signal. Try twirling the varco rod for radio waves.
g .. If the sixth step is successful then the next step is to trim the radio in order to get maximum results.

The part of the radio that is trimmed is the MF amplifier, oscillator, and antenna spool. Metering can be done in a simple way or using complete tools. Simple metering uses a plastic trim screwdriver that can be assisted by the injector signal (SI). Metering with a screwdriver and the aid of an injector signal will get fairly good results, although less satisfactory when compared to using a complete tool. Metering with complete tools using a signal generator and multitester. Signal generator is a tool for generating frequency, whether it contains radio (modulated) or not. Multitester is a combination of several kinds of measuring instruments.

a. MF Amplifier Metering The simple steps for measuring MF amplifier using a screwdriver tip are as follows.

1) Turn on the radio.
2) Radio tuning sound to one of the small and distant transmitters. If a large and close transmitter is used, then the small and far transmitters will not be captured.
3) With the tip of a screwdriver, turn the ferrite rod of transformer MF III, MF II and MF I until you hear the loudest sound at the LS (repeat with another wave).

The steps of a simple MF amplifier with the help of the injector signal are as follows.
1) Turn on the radio.
2) Connect the injector clamp wire to the (+) pole of the radio.
3) While turning the ferrite rods of the MF III, MF II and MF I transformers, inject the injector cable into the base of the MF amplifier (TR4 and TR5) until the LS sounds "tiutiut ....." the loudest. b. Oscillator Metering The purpose of oscillator metering is to obtain the loudest sound from all broadcast transmitters and to match the needle of the waveform to the scale of the wave against the varco (variable condensator) rotation.
The steps for measuring the oscillator spool are as follows.
1) Turn on the radio.
2) Place the needle of the wave on a certain scale, for example a 75 m wave or other wave that has known the name of the transmitter. To speed up this work, use a radio as a benchmark.
3) Turn the oscillator spool ferrite up and down until you hear a sound that corresponds to the wave in question, for example a 75 m wave.
4) Move the wave needle to another wave scale, for example 90 m.
5) Turn the oscillator spool ferrite until you hear a sound that corresponds to the other wave in question, namely the 90 m wave. The result of good metering is that between the wave scale of 75 m and 90 m, the same sound is heard.
6) If after being moved to another wave (by way of the varco detour) a whistle is heard, then the tuning must be repeated.

c. Antenna Spool Metering
Metering the antenna spool aims to obtain the strongest radio sound. An incorrect location of the antenna spool on the ferrite rod will produce a sound that is not good and not loud.
The method of measuring the antenna spool is as follows.
The antenna spool is shifted from side to side with the tip of a screwdriver or other insulating material until the LS is heard the loudest sound. Metering the antenna spool is accompanied by shifting the position of the antenna spool and rotating the varco.

If using a signal injector (SI) the steps are as follows.
1. Turn on the radio and S.
2. Ground S is connected to the radio + pole and the injection pen is attached to the antenna spool leg.
3. Move the antenna spool from side to side until the LS hears the loudest "kiit" sound.

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