Amateur radio is truly one of the largest fraternities in the world, open to persons of all ages and nationalities. This book allows you to get in on the ground floor of amateur radio.
Who Can Become a Ham Radio Operator?
Organizations such as the Courage HANDIHAM System (see Chapter 2) provide a wide range of services to assist people with disabilities. We will tell you how to prepare and apply for your ham permit in Chapter.
New Avenues into Amateur Radio
About Amateur Radio
Amateur radio provides a challenging entry to explore much of the technology involved in many of these areas. Many of NASA's space shuttle flights include Shuttle Amateur Radio Experiment (SAREX) contacts with amateur radio operators.
A History of Amateur Radio
There are many fascinating aspects of amateur radio: talking to fellow hamsters, participating in emergency communications during disasters, studying electronics technology, or building ham equipment and antennas using state-of-the-art electronic components. Before we get into the details of amateur radio and how to pass the FCC exam for an amateur radio license, let's take a look at the fascinating history of amateur radio.
Early pioneers
The first major use of the new wireless telegraph sets was to provide marine communications. By 1905, spark gap transmitters and cohering detector receivers were installed on many merchant ships and offshore vessels.
Beginning of amateur radio
Early wireless amateur radio equipment. a) Early crystal receiver that used a dual-sided antenna tuning inductor, a “Cat Whisper” detector, a telephone blocking capacitor, and headphones. By this time, the number of persons interested in or participating in amateur radio had grown to an estimated 10,000 or more.
First licenses for amateur radio operators
Through the dynamic leadership of Hiram Percy Maxim, the ARRL grew to become the largest amateur radio organization in the United States. In 1915, the ARRL introduced QST, an amateur radio magazine devoted solely to amateur radio pursuits.
The death knell for amateur radio
In addition, some of the equipment from the more extensive amateur stations was released to the government for use by the military. This legislation would have granted control of all forms of radio communications to the Department of the Navy.
The golden age of amateur radio
Some of the amateurs dusted off their old spark gap transmitters and crystal detector receivers for instant operation. Others began to adapt the new vacuum tubes for both transmitter and receiver use.
Amateur Radio—A Scientific Hobby
The old crackling sounds of spark gap transmitters have been replaced by the clear, sharp signals of continuous wave (cw) transmitters and voice modulated devices. The availability of the operational amplifier has allowed amateurs to design and build active filters for cw (Morse code) applications with bandwidths less than 100 Hz.
Amateur Radio Public Service
Although space does not permit a complete overview of these activities, some of the major disasters in which hams provided emergency communications were Hurricane Carla in Texas (September 1961), Hurricane Hugo in the Caribbean and Puerto Rico (September 1989), and Loma Prieta earthquake (October 1989). Currently, amateurs provide much of the personal communications for Antarctic research station staff.
The Path into Amateur Radio—The Technician Class License
Sporadic E-layer propagation is a favorite of 6-meter hams, which provide short band gaps at distances up to about 3000 km (1200 miles). More extensive 70 centimeter stations could also enable long-distance contacts between 'earth-bound' hams over a distance of up to about 2,000 km (1,200 miles).
The Entrance to the World of Amateur Radio Is Easy
For more information about the VE test teams, please contact your local amateur radio club or ARRL at the address above. Virtually everyone in the United States, regardless of age, is eligible to take the FCC amateur radio exams.
The Federal Communications Commission
When you are ready to take the Technician (or higher) license exam, a local VE team made up primarily of EXTRA class hams will be available to schedule the exam.
The FCC Volunteer Examiner Program
FCC Amateur Radio Operating Classes
This "top prize" in ham radio gives you full operating privileges on all ham bands. Note that the technician class license allows the beginner to gain valuable experience in almost all types of amateur radio communications.
The Amateur Radio Frequency Spectrum
Each amateur radio band exhibits a unique set of characteristics that require special techniques to design and build antennas, transmission lines, transmitters and receivers. For example, the 40-meter band is approximately TABLE 2.1 FCC Amateur Radio Licenses, Exam Requirements, and Operation.
FCC Rules and Regulations
Amateur Radio Service
- Basis and purpose. The rules and regulations in this part are designed to provide an amateur radio service having a fundamental
- Definitions
A station in an amateur radio service consisting of the apparatus necessary to carry out radio communications. A dotted code, as defined in the International Telegraph and Telephone Committee (CCITT) Recommendation F.1 (1984), Division B.I. Using a control operator who directly manipulates the operating settings on the station to achieve compliance with FCC rules.
Station license required
The manager must be a person who holds an Amateur Extra, Advanced, General, Technician Plus or Technician operator license. A RACES station license can only be held by the person who is the license manager appointed by the official responsible for the governmental agency served by the civil defense organization in question.
Operator license
To whom the granting of a permit for an amateur operator/primary station appears in the collection of ULS collective permits, or The person named in the grant of the operator's license is authorized to be the supervisory operator of the amateur station with the privileges granted for the class of operator specified in the license.
Restrictions on station location
The person named in an operator's license grant of Novice, Technician, Technician Plus, General, or Advanced class who has properly submitted an FCC Form 605 document to the administering VEs requesting examination for an operator's license for a higher class, and who is the holder of a CSCE indicating that the person has completed the required examinations within the previous 365 days, is authorized to exercise the rights and privileges of the higher operator class until the final processing of the application or until 365 days after passing the exam, whichever comes first. Power PEP (peak envelope power) input to the antenna except for repeater stations only, power rejection is based on ERP (effective radiated power). 2) If the routine environmental evaluation indicates that the RF electromagnetic fields may exceed the limits in Section 1.1310 of this chapter and are available for such electromagnetic fields.
Station antenna structures
Application for new license grant
Application for a modified or renewed license
Revocation of the station license or suspension of the operator's license may result when correspondence from the FCC is returned as unwarranted because the grantee has not provided the correct address.
License term. An amateur service license is normally granted for a 10-year term
General standards
Station licensee responsibilities
The FCC will assume that the station licensee is also the control operator unless evidence to the contrary is found in the station records. When deemed necessary by an EIC to ensure compliance with the FCC Rules, the station licensee shall maintain a record of station operations containing such information as the EIC may require pursuant to Part 0.314(x) of the FCC Rules.
Control operator duties
Station control
When deemed necessary by an EIC to ensure compliance with FCC rules, the station licensee shall maintain a record of station operation containing such information as the EIC may require under Part 0.314(x) of the FCC Rules. e) No station may be automatically controlled while transmitting third party communications, except a station transmitting an RTTY or data broadcast.
Authorized transmissions
Prohibited transmissions
A club station control operator may accept compensation as an incident in connection with a teaching position during periods when an amateur station is used by that teacher as part of classroom teaching at an educational institution. Prior approval for shuttle transfers must be obtained from the National Aeronautics and Space Administration.
Third party communications
This prohibition does not apply to a message for any third party who is eligible to be a control operator of the station. The third party may not be the subject of a cease and desist order related to amateur service operations that is still in effect.
Station identification
Each indicator must be separated from the exclamation point by a forward slash (/) or by some appropriate word indicating forward slash. If an indicator is assigned by itself, it must be included before, after, or before and after the call sign.
Restricted operation
For a control operator who requested a license modifica-. transition from beginner, technician or general operator to advanced class: AA; or For an operator who has applied for a license change from a beginner, technician, general or advanced operator to an amateur extra class: AE.
Beacon station
For a control operator who has requested a license change from the Novice or Technician class to the General class: AG (3). For a control operator who has requested a license change from Novice, Technician, General or Advanced Class operator to Amateur Extra Class: AE. G).
Repeater stations
Space station
The beacon can transmit one-way communication. subject to the privileges of the class of operator's license held by the controller. The space station must be capable of terminating transmissions by remote command whenever such termination is ordered by the FCC.
Telecommand of model craft. An amateur station transmitting signals to control a model craft may be operated as fol-
Emission standards
A transmitter built before April 15, 1977 or first marketed before January 1, 1978 is exempt from this requirement. e) The average power of any spurious emission from a station transmitter or external RF power amplifier transmitting on a frequency between 30–225 MHz shall be at least 60 dB below the average power of the fundamental tone. A transmitter built before April 15, 1977 or first marketed before January 1, 1978 is exempt from this requirement. f) The following standards and limitations apply to transmissions on the frequencies specified in part 97.305 of this part:.
Transmitter power standards
RTTY and digital code transmission rates are measured in baud or bits per second. Baud can be thought of as the rate at which a signal passes, e.g. 300 baud represents 300 signal transitions per second.
Operation during a disaster
The declaration will indicate any special conditions and special rules that stations must comply with during the communications emergency. A request for a declaration of a temporary state of emergency must be addressed to the RIC in the area concerned.
Station in distress
Before 1984, the FCC administered amateur radio exams at select FCC facilities across the country. Since that time, the FCC has delegated administration of all amateur radio examinations to qualifying (or accredited) amateurs and amateur organizations such as the ARRL and the W5YI Group.
Qualifying for an amateur operator license. Each applicant must pass an examination for a new amateur operator
However, if you have the opportunity to also prepare for the Element 1 Morse test and the Element 2 written exam for the Technician Class license, it's the best of both worlds. The following sections of Part 97 govern the amateur test sessions for all Technician (and above) Class license examinations.
Element standards
Every candidate must pass the new amateur operator exam. necessary for the proper performance of the duties of the license holder for amateur services.
Amateur Call-Sign Allocations
Call signs for these licensees use a 1 3 format with the first letter of the prefix a letter K, N, or W. Initial class licensees located outside the continental United States were issued 2 3 format call signs with the prefixes KL, NL or WL (Region 11); NP or WP (Region 12); and KH, NH, or WH (Region 13).
How to Learn International Morse Code
General or Technician Class licensees located outside the continental United States will be issued call signs with a 2 3 format prefixed with KL, NL or WL (Region 11); NP or WP (Region 12); and KH, NH or WH (Region 13). NEWS, CLUB AND MILITARY RECREATION STATION CALL SIGNS Although these call signs, a 2 3 format, are no longer issued by the FCC as of May 15, 2000, holders of current Novice Class licenses may retain their licenses indefinitely.
What is Morse Code?
The international Morse code uses individual combinations of dashes and dashes to represent the 26 letters of the alphabet, the 10 digits (0 to 9), and a group of special symbols and abbreviated expressions. For example, the letter H would be "di-di-di-dit". The letter R will be represented by "di-dah-dit". Table 2.3 provides a complete list of the recommended International Morse Code characters set for amateur radio communications.
How code is transmitted
F buat-buat O buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-buat-lakukan -dah-di-dah Z sudah-dah-di-it. Tanda soal (?) done-done-done-done-done Jemputan untuk menghantar (K) done-done-done Bar putus (/) done-done-done-done-done Tamat mesej (AR) done-done -di - dah-dit Ralat dalam pemindahan di-di-di-di-di-dit Tamat kerja (VA) di-di-di-dah-di-dah.
Who can learn Morse code?
You must establish an adequate schedule for code practice sessions and strictly adhere to this schedule. A code practice oscillator, a hand wrench, and a source of code practice signals are considered essential tools for learning to send and receive international Morse code.
The FCC Written Examinations
While operating, the arm should be positioned to rest on a flat surface and the key should be grasped loosely by the thumb, forefinger and forefinger.
The VEC question pool
Since the Technician Class exam is the easiest of all the amateur exams, many beginners don't put enough effort into studying and preparing. As you can see in Table 2.5, the technician exam contains nine questions on FCC rules and five questions on operating procedures.
Scheduling the examination
The process of writing down the information on the cards results in significant preservation of this material. Then, through constant review, you can begin to separate the cards into two piles—known and unknown.
Taking the examination
This way, the easy questions can be answered and you can return to the more difficult questions for additional study. The FCC allows you to retake the test at any time convenient for the VE.
Definitions
In this chapter we will take a closer look at some of the basics of radio communication. Scientists have recorded the number of sunspots that appear on the sun's surface for the past 300 years and have determined that the number of sunspots reaches a maximum about every 11 years.
The Radio Circuit—Transmitter to Receiver
Ionosphere The ionosphere consists of layers of ionized air at altitudes above the earth's surface ranging from about 7 to 250 miles (or about 11 to 402 kilometers). The heights of these layers vary from daylight to darkness, depending on the position of the sun relative to the earth's surface.
The Electromagnetic Spectrum
Some of these factors are RF output power levels, antenna directivity and gain characteristics, radio frequencies used and associated propagation characteristics at those frequencies, and receiver performance. The ever-increasing number of transmitters in an already crowded spectrum and interference from unintended transmitters also contribute to the difficulties in achieving reliable radio communications.
Frequency and wavelength
Because electromagnetic waves travel at the speed of light (meters per second) in free space, the frequency of the wave can be determined in complete cycles per second (or Hz) by dividing the wavelength in meters. Also, if the frequency of a wave is known, the wavelength can be determined by dividing the frequency in hertz.
The radio frequency spectrum
The need for mathematical calculations in the written examinations for the technician class license is extremely limited. Most amateur radio communications begin in the 1800–2000 kHz portion of the MF band and extend through the EHF band.
Wave propagation
Types of Propagation
In the HF bands and above, the radio waves are attenuated by the earth's surface and rarely extend beyond 20 to 30 miles (or about 30 to 50 kilometers). Thus, amateur radio communications in the HF bands and above cannot rely on ground wave propagation over long distances.
The Effects of the Ionosphere on Radio Communications
The formation of these layers of charged particles and electrons is attributed to intense solar radiation. It is the nature of the ionosphere that affects the quality and distance of radio communications.
Ionospheric layers
The layers of the ionosphere extend up to about 250 miles (400 kilometers), depending on the intensity of solar radiation. The rotation of the Earth on its axis, the orbital travel of the Earth around the Sun, and the variable activity of sunspots on the surface of the Sun cause the layer of charged particles in the ionosphere to constantly change.
Sunspots affect the ionosphere
The ionosphere differs from other areas of rarefied air in that it contains large numbers of free ions (charged particles) and electrons. During periods of high sunspot activity, the Sun's radiation increases, causing more intense ionization of the atmosphere.
High sunspot activity
At approximately 11-year intervals, the number of sunspots increases to a maximum that ranges from about 60 to 200. During minimum sunspot activity, the number of sunspots can decrease to zero for short periods of time.
Propagation characteristics of the ionosphere
No waves at night and only occasional waves during the day during minimal sunspot activity. Very few daytime waves in the sky and almost no waves at night during minimal sunspot activity.
Nighttime propagation conditions
Direct current Direct current (DC) can be described as a flow of current in only one direction. Electromotive force Electromotive force (emf) can be described as a difference in potential, or voltage, which forces current to flow in a conductor.
Fundamentals of Electricity
Atoms and matter
Negative and positive charges
Electricity—the flow of electrons
These attractive and repulsive forces can be thought of as electrical pressure, similar to the pressure in a water pipe that forces water through the pipe. The flow can be thought of as analogous to the amount of water flowing in the pipe at any given time.
Units of voltage and current
Negatively charged electrons are immediately attracted to the positive pole of the battery, while the negative pole repels electrons.
Conductors and insulators
Resistance and resistors
Resistors used in electronic circuits can have resistance values ranging from less than one ohm to millions of ohms (or megohms). The size of the resistor usually indicates the power rating, and the color bands or stripes provide a coding for the value of resistance and tolerance factor.
Some Basic Electrical Laws
Ohm’s law
Resistors in series
Resistors in parallel
For example, if four 100 ohm resistors are connected in parallel, the resulting resistance is 100/4 or 25 ohms. When two resistors with unequal values are connected in parallel, the resulting resistance is found by the following equation:
Series-parallel combinations
A more complex equation is required to calculate the parallel resistance of three or more unequal resistors.
Current flow in series dc circuits
Batteries connected in series have a total voltage equal to the sum of the individual batteries. Batteries connected in opposite series have a total voltage equal to the difference of the individual batteries.
IR voltage drops
Current flow in parallel dc circuits
Magnetism
The magnetic field
If the north pole of one magnet is placed near the south pole of another magnet, the two magnets will be attracted to each. However, if two similar poles (north-north or south-south) of two magnets are placed close together, there is a repulsive force and the two magnets will try to move away from each other.
Temporary and permanent magnets
The more lines there are per unit area, the stronger the magnetic field will be. A magnet, on the other hand, will always have a north pole at one end and a south pole at the other end.
Electromagnetism
The magnetic lines of force associated with each turn of the conductor combine in the same direction with the magnetic lines of force from the other turns. Thus, more lines of magnetic force will be concentrated in a small space, all passing through the center of the coil.
Magnetomotive force (MMF)
If the conductor is wound in the form of a coil, as in Fig. 4.15, the strength or intensity of the magnetic field is increased many times. Electric motors, relays, solenoids and headphones are some of the devices that use electromagnets to perform work functions.
Electromagnetic induction
Alternating current and voltage
The ac sine wave
The term rms is short for "root mean square", a mathematical expression to describe the effective value of an ac waveform. The relationship between peak AC voltage and rms voltage for a sine waveform is given by the following equation.
As the AC frequency increases, the capacitive reactance in ohms decreases. As the frequency increases, the AC voltage will increase until finally the inductor acts as an open circuit.
Capacitors and Capacitance
In a dc circuit, only the dc resistance of the coil provides opposition to current flow. The amount of capacity developed by such a capacitor is related to the surface area of the plates.
How capacitors work
This current continues until the voltage across the capacitor plates is equal to the battery voltage, in this case 6 volts. At this point the voltage across the capacitor drops to zero and the capacitor discharges.
Capacitor voltage ratings
The positive and negative charges on the capacitor plates create an electric field between the two plates. The charged capacitor can now be disconnected from the battery, retaining an electrical charge that can do work (Fig. 4.21B).
Connecting capacitors in parallel
In addition, when connecting electronic capacitors in circuits with DC potentials, the + terminal of the capacitor must be connected to the positive terminal of the circuit.
Connecting capacitors in series
Capacitive reactance
Otherwise, the electrolytic capacitor may be damaged by the dc potential. AC voltage being impressed on the capacitor. Note that when several capacitors are connected in series or parallel, the capacitance resulting from such combinations can be used to find the total capacitive reactance involved.
Phase angle of capacitors
Testing capacitors
Further tests with a capacitor tester are required to ensure that the capacitor has the required capacitance. With a little experience, you will be able to check almost all types of capacitors with a multimeter.
Inductors and Inductance
In most cases, the capacitor must be removed from the circuit for the test to make sense.
Inductance
When the conductor is wound in the form of a coil, the inductance is increased many times depending on the number of turns. Most coils used in audio and radio frequency circuits have values of inductance in the millihenry and microhenry range.
Series inductors
Parallel inductors
Inductive reactance is the resistance to the flow of alternating current developed by an inductance. This is caused by the opposing induced voltage created by the expanding and contracting magnetic field.
Phase angle of inductors
The voltage levels at 0, 180 and 360 degrees are at a maximum because the rate of current change is highest at these angles. However, the induced voltage drops to zero at 90 and 270 degrees because the current does not change in value at these angles.
Transformers
We don't mean actual current values, but how fast the current value is changing. The same receiver may contain an audio output transformer to drive a low-impedance speaker, or RF and IF transformers to couple RF and IF signals between stages.
Basic transformer concepts
The ratio of current in the primary winding to current in the secondary winding is the inverse of the turns and voltage ratios. IS the current in the secondary winding in amperes IP is the current in the primary winding in amperes.
Testing inductors and transformers with a multimeter
ISIP IP (Eq. 4.25) One interesting aspect of step-up or step-down transformers is that the step-up transformer reduces the available output current while the step-down transformer allows for an increase in current in the secondary winding. The equations just given for finding output voltage and current levels must be used for each secondary winding in relation to the primary winding.
Impedance and phase angles
The actual resistance will depend on the size of the wire and the number of turns. Any analysis of impedance must take into account the phase angle of the component or circuit involved.
Resonance and tuned circuits
However, above and below the resonant frequency, the LC network exhibits inductive and capacitive reactance, respectively. Above or below the resonance frequency, the network appears as a capacitive or inductive reactance, respectively.
The Q of resonant circuits
Power Relationships
Power in a dc circuit
Power in an ac circuit
The total power supplied to the AC circuit, called apparent power, consists of the actual power consumed by the resistive elements and the reactive power absorbed (but not dissipated) by the reactive elements. Apparent power, which is defined as the product of the current through the circuit and the voltage flowing through the circuit, is expressed in volt-amperes instead of watts.
Maximum power transfer
The vacuum tube uses a controlled flow of electron flow to perform functions such as rectification or amplification. Diode The diode is the simplest form of a vacuum tube and consists of two electrodes, a cathode and a plate.
Vacuum Tubes
Thermionic Emission
For a given material and temperature, the number of free electrons contained in the cloud will remain relatively constant. Once produced, the cloud of free electrons can be made to flow in a specified direction to other electrodes in the tube and perform functions such as rectification and amplification.
General Types of Vacuum Tubes
Diodes
When we move the switch S1 to position B, a positive voltage potential is placed on the plate and free electrons will flow to the plate. Moving the switch S1 to position C results in making the plate negative with respect to the cathode.
The diode as an ac rectifier
Using Ohm's law, we can find the actual plate current (amperes) by dividing the plate voltage (volts) by the resistance (ohms) of R1. An alternative method of finding the plate current is to break the circuit at the plate terminal and connect a DC ammeter.
Triodes
This allows most electrons from the cathode to flow unhindered to the plate. Dimensions, shapes and spacing of the three electrodes used in triodes vary depending on the intended applications.
How triodes work
As the negative grid potential increases, the plate current eventually reduces to zero. If the positive grid voltage increases beyond a certain amplitude, all electrons emitted from the cathode will flow to the plate.
Triode amplification action
Because the grid is now at zero voltage potential, this has virtually no effect on the negatively charged electrons emitted from the cathode. This condition is known as cutoff, and the amplitude of the mains voltage required to cause this condition is called the cutoff voltage.
Limitations of triodes
Capacitors C1 and C2 isolate the signal input and output connections from the tube's DC voltage. By using an oscilloscope to measure input and output peak-to-peak signal levels, we can determine the voltage gain of this or other similar amplifiers.
Tetrodes and Pentodes
Another major limitation of the triode is that it does not meet all the gain or amplification requirements needed in receivers, transmitters, and other electronic equipment.
The tetrode
This screen-to-grid voltage, which is usually lower than the plate voltage, provides another desirable advantage over the triode. The plate current is independent of the plate voltage because the screen grid supplies a positive potential that draws the electrons from the cathode to the plate.
Limitations of the tetrode
As long as the plate voltage is higher than the screen voltage, the plate current in the tube depends mainly on the screen grid voltage and very little on the plate voltage. This action of the tetrode leads to a higher amplification factor and increases plate resistance compared to the triode.
The pentode
The pentode as an amplifier
Specific vacuum tube operating specifications and design data for triodes, tetrodes, and pentodes are available in many vacuum tube manuals and electronic handbooks such as The ARRL Handbook.
Beam-power tubes
Gas-filled tubes
Cathode-ray tubes
Diodes, Transistors, and other Semiconductor devices
How semiconductor devices are made
The pn junction
This electrochemical force is responsible for the operation of the p-n junction diode and the transistor. Note that the p-type material in the p-n junction diode is called the anode and the n-type material is called the cathode.
How diodes work
Such diodes can be used in AC power supplies involving low power receivers and transmitters. These high-power rectifiers are used in the power supplies of powerful amateur radio transmitters.
Reverse bias
Thus the free electrons in the n-type material cross the junction and move towards the anode. At the same time, holes in the p-type material move toward the anode terminal because they are attracted to the negative potential.
Diode circuits
Two diodes can be connected to form a full-wave rectifier circuit when the secondary winding of the transformer has a center tap. The negative half of the AC signal is unaffected because the diode is reverse biased and does not conduct.
Special-Purpose Diodes
The zener diode
This type of voltage regulator can be used to power a transistor radio from an automobile's electrical system. With the engine running, the car's electrical system can supply up to 14 volts from the generator or alternator.
The varactor diode
When the engine is turned off, the voltage drops to about 12 volts as the battery is charged. Regardless of the varying voltage supplied by the system, the zener regulating circuit maintains a constant 9-volt supply to the transistor.
Transistors
Basic amplifier circuits for the pnp and npn transistors are compared to the triode vacuum tube in Fig. Field effect transistors are generally divided into two types: the junction FET (or JFET) and the isolated gate FET (or IGFET). .
Bipolar transistor construction
Most of the free electrons entering the base float over the narrow region and end up in the collector. For example, approximately 95 percent of the free electrons pass through the base to the positive collector.
Common-base amplifying circuits
An important parameter or characteristic of the common base configuration is the current gain. The amplifier action of the common-base configuration is based on the ac input signal changing the forward bias across the emitter-base pn junction.
Common-emitter amplifier circuits
The collector current, on the order of a few milliamps, flows in the collector-emitter circuit. The voltage gain of the common-emitter configuration is comparable to that of the common-base configuration—usually on the order of 100 to 1000.
Common-emitter design considerations
The base resistance, RB, can now be calculated based on IB 8 A. The base-emitter pn junction is forward biased, resulting in a voltage drop of about 0.7 volts for silicon transistors. If a germanium transistor is used in this type of circuit, the base-emitter voltage, VBE, is about 0.3 volts.).
Variations in transistor characteristics
