One reason to upgrade right away is that you’re in study mode already. There’s no need to get back in the habit of studying and getting used to taking tests again. While the General Class test is more difficult than the Tech test, there are lots of good resources, both in print and on the Internet, to help you pass. These include my No-Nonsense General Class License Study Guide (http://www.kb6nu.com/tech-manual/).

Another reason upgrade to General Class is that it will make you a better ham. Seriously. Even if you memorize the answers to all of the questions in the question pool, you’re bound to learn something. That knowledge could come in handy when you want to put up a new antenna, buy a new radio, or determine the best band to use for a particular communication.

Perhaps the best reason to upgrade to General is that it gives you more privileges on the HF bands. While talking on the local repeater may be fun, let’s face it, there are only so many folks to talk to. By getting on the HF bands, you’ll be able to talk to thousands of hams all around the world, not just around the corner. That’s why many hams, including me, think that the shortwave (HF) bands are where the magic happens. As a General Class operator, you’ll get access to all the HF bands, including 20m, and you get to operate phone on them as well as CW.

Operating the HF bands literally expands your horizons. You get to meet hams from all over the world, not just around the corner. If you haven’t yet operated on the HF bands, you don’t know what you’re missing. To get a taste of HF operation, ask a ham with an HF station if you can visit him sometime and watch him operate. Chances are he’ll let you make a few contacts of your own. You may also get the opportunity to operate an HF station during Field Day or if your club has its own club station.

Another thing that you can do as a General Class licensee is become a Volunteer Examiner (VE). Becoming a Volunteer Examiner and helping others get involved in amateur radio is a great way of giving back.

A General Class license will let you do more and have more fun with amateur radio. If you haven’t yet taken the Technician test, you should be aware that you can take both the Tech and the General (and even the Extra) Class tests at the same test session. If you prepare for both tests, you could walk out of your first test session with a General Class license and skip the Technician Class altogether.

The person who fills this position will, among other duties, identify, review and organize resources needed by license instructors, teachers and Scout leaders, develop curricula/lesson plans, instructional media for instruction of ham radio license and other ham radio related topics (including radio science and basic electronics topics for use by classroom teachers) and develop an orientation course for license instructors and materials for instructor training. Candidates should hold an Amateur Extra class license (or be willing to achieve this within one year from date of hire) and a wide range of operating experience. Experience with instructional media is a plus. A Bachelor’s degree, along with teacher certification (and/or experience as a teaching or training professional) with Amateur Radio, electronics, science or technology subjects is required. Click here for a job description.

Much has been written about station grounding. One thing’s for sure. A station’s safety ground is not adequate as an RF ground. The reason for this is that conductors present different impedances at different frequencies.

A wide flat copper strap is the type of conductor that would be best for minimizing losses in a station’s RF ground system. (E9D14) The main reason for this is that at RF tends to be conducted near the surface of a conductor. The more surface area there is, the lower the impedance to ground.

To  minimize inductance, it’s best to keep the RF ground connection as short as possible.  An electrically-short connection to 3 or 4 interconnected ground rods driven into the Earth would provide the best RF ground for your station. (E9D15)

For many amateurs, there first antenna is a trapped vertical antenna. Mine was a Hy-Gain 14AVQ, which was resonant on 40m, 20m, 15m, and 10m.  One advantage of using a trapped antenna is that it may be used for multiband operation. (E9D12) Another big advantage is that it doesn’t require a lot of space when compared to a dipole antenna.

A disadvantage of using a multiband trapped antenna is that it might radiate harmonics. (E9D07) For example, if your 40m transmissions have high harmonic content on 20m, and the multiband vertical is also resonant on 20m, it will radiate those harmonics.

Another disadvantage is that they are generally shorter than 1/4 wavelength. The bandwidth of an antenna is decreased as it is shortened through the use of loading coils. (E9D08) Not only do they have a smaller bandwidth, but loaded verticals are also less efficient than full, quarter-wavelength verticals. One way to lessen this disadvantage is to use top loading. An advantage of using top loading in a shortened HF vertical antenna is improved radiation efficiency. (E9D09)

Mobile antennas are almost always shorter than a quarter wavelength. What happens to the feed point impedance at the base of a fixed-length HF mobile antenna as the frequency of operation is lowered is that the radiation resistance decreases and the capacitive reactance increases. (E9D13) To transform this impedance to 50 ohms, they use a loading coil. The function of a loading coil as used with an HF mobile antenna is to cancel capacitive reactance. (E9D11)

Because short verticals, such as those used in mobile installations are inherently inefficient, you should do whatever you can to make them as efficient as possible. An HF mobile antenna loading coil should have a high ratio of reactance to resistance to minimize losses. (E9D06)

The ratio of reactance to resistance is called Q. A high-Q loading coil should be placed near the center of the vertical radiator to minimize losses in a shortened vertical antenna. (E9D05)

An antenna that used to be very popular when TV antennas used 300-ohm feedline is the folded dipole. The reason for this is that that approximate feed point impedance at the center of a two-wire folded dipole antenna is 300 ohms. (E9D10) Amateurs would use the 300-ohm feedline for both the antenna elements and the feedline, and then use a balun or some other matching device to match the 300 ohm impedance to the transmitter output impedance.

Finally, there are four miscellaneous questions about directional antennas. The first is about how beamwidth and antenna gain are related. The beamwidth of an antenna decreases as the gain is increased. (E9D03) This is intuitively obvious. An antenna does not amplify a signal but instead focuses the power. So, when we say that the gain is increased, what we’re really saying is that we’re focusing the power into a smaller beam.

On the VHF and UHF bands, Yagi antennas are operated either horizontally for weak-signal work and vertically for FM operations. In some cases, however circular polarization is desirable. You can use linearly polarized Yagi antennas to produce circular polarization if you arrange two Yagis perpendicular to each other with the driven elements at the same point on the boom and feed them 90 degrees out of phase. (E9D02) The disadvantage to this approach is, obviously, that you need two antennas, instead of just one to achieve circular polarization.

For satellite operation, some hams have antenna systems that can tilt up and down as well as rotate. This is so the antenna can point directly at the satellite as it passes overhead. It is desirable for a ground-mounted satellite communications antenna system to be able to move in both azimuth and elevation in order to track the satellite as it orbits the Earth. (E9D04)

Parabolic antennas are often used at microwave frequencies to direct a signal in a particular direction. One thing to keep in mind is that gain increases by 6 dB if you are using an ideal parabolic dish antenna when the operating frequency is doubled. (E9D01) Also keep in mind that, as pointed out earlier, the beamwidth is narrower as well.

This type of logic is generally called positive logic. Positive Logic is the name for logic which represents a logic “1″ as a high voltage. (E7A11) The logic may be reversed, though. That is to say that a high voltage may represent a logic 0. Negative logic is the name for logic which represents a logic “0″ as a high voltage. (E7A12)

The microcomputers that control today’s transceivers, for example, are very complex digital circuits. These complex digital circuits are made by combining many smaller building blocks called logic gates. These gates perform basic digital logic functions.

Table E7-1. This two-input NAND truth table show the output (Q) for each combination of inputs (A,B).

One of the most basic digital circuits in the NAND gate. The logical operation that a NAND gate performs is that it produces a logic “0″ at its output only when all inputs are logic “1.” (E7A07)

This logical operation can be described by a truth table. A truth table is a list of inputs and corresponding outputs for a digital device. (E7A10) Table E7-1 shows a truth table that describes the operation of a two-input NAND gate. A and B are the two inputs; Q is the output.

Table E7-2.

Other types of gates perform different logical functions. The logical operation that an OR gate performs is that it produces a logic “1″ at its output if any or all inputs are logic “1.” (E7A08) Table E7-2 shows a truth table that describes the logical operation of an OR gate.

The logical operation that is performed by a two-input exclusive NOR gate is that it produces a logic “0″ at its output if any single input is a logic “1.” (E7A09) Table E7-3 shows a truth table that describes the logical operation of an OR gate.

Table E7-3.

Flip-flops are circuits that are made from combinations of logic gates. The output of a flip-flop is not entirely dependent on its inputs; it is also dependent on the current value of its output.

As an example, let’s look at the SR or RS flip-flop. An SR or RS flip-flop is a set/reset flip-flop whose output is low when R is high and S is low, high when S is high and R is low, and unchanged when both inputs are low. (E7A13) So, once set to a particular value, the output will not change when both inputs are set to low.

Some flip-flops are clocked. That is to say that they only change states when a clock signal input changes states. A D flip-flop is an example of this type of flip-flop. A D flip-flop is a flip-flop whose output takes on the state of the D input when the clock signal transitions from low to high. (E7A15) A JK flip-flop is a flip-flop similar to an RS except that it toggles when both J and K are high. (E7A14)

Another type of flip-flop is the T flip-flop. The T flip-flop is so called because for each transition from low to high on the flip-flop’s T input, the output “toggles” from 0 to 1 if the output was already at 0, and from 1 to 0 if the output was already at 1. Two output level changes are obtained for every two trigger pulses applied to the input of a T flip-flop circuit. (E7A02) See figure E7-1 below.

The output of a T flip-flop changes state every time a clock pulse appears on the T input. This effectively divides the input frequency by a factor of two.

A flip-flop can divide the frequency of a pulse train by 2. (E7A03) Consequently, 2 flip-flops are required to divide a signal frequency by 4. (E7A04)

A flip-flop is a bistable circuit. (E7A01) What that means is that its output is stable in either state. An astable multivibrator is a circuit that continuously alternates between two states without an external clock. (E7A05) In other words, it is an oscillator.

A monostable circuit is one that is stable in one state but not the other. One characteristic of a monostable multivibrator is that it switches momentarily to the opposite binary state and then returns, after a set time, to its original state.(E7A06) A trigger pulse causes the monostable vibrator to switch to the unstable state, and it stays in that state for a set period, no matter how long the trigger pulse.

Resources
Wikipedia: Multivibrator (https://en.wikipedia.org/wiki/Multivibrator)

To enter a contest and be considered for awards, you must submit a log of your contacts.  The contest organizers will check the log to make sure that you actually made the contacts that you claim. To make this easier to do, most contest organizers now request that you send in a digital file that lists your contacts in the Cabrillo format. The Cabrillo format is a standard for submission of electronic contest logs. (E2C07)

In contest operating, operators are permitted to make contacts even if they do not submit a log.  (E2C01) If you do not submit a log, you obviously cannot win a contest, but there are several reasons why you still might choose to participate in a contest. For example, for big DX contests, some amateurs travel to locations where amateur radio operation is infrequent. Making contact with those stations during a contest gives you an opportunity to add countries to your total.

Another reason is that it will give you a good idea of the capabilities of your station. If, for example, during a contest, you need to call repeatedly before a DX station replies, it might mean that you should improve your antenna system.

There are some operating practices that are either prohibited or highly discouraged. On the HF bands, for example, operating on the “WARC bands,” is normally prohibited. Therefore, 30 meters is one band on which amateur radio contesting is generally excluded. (E2C03). The other “WARC bands” are 17 meters and 12 meters.

Another prohibited practice is “self-spotting.” Self-spotting is the generally prohibited practice of posting one’s own call sign and frequency on a call sign spotting network. (E2C02) The reason this is prohibited is that doing so would give you an advantage over other operators.

During a VHF/UHF contest, you would expect to find the highest level of activity in the weak signal segment of the band, with most of the activity near the calling frequency. (E2C06) VHF/UHF contesters stay away those portions of the band that are normally reserved for FM operation. That being the case, 146.52 MHz is one of the frequencies on which an amateur radio contest contact is generally discouraged. (E2C04) 146.52 MHz is the national FM simplex calling frequency.

To see how this works, let’s consider the RC time constant. The time constant of an RC circuit is equal to the resistance in the circuit times the capacitance, or simply R x C. For example, the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors, all in parallel is 220 seconds. (E5B04)

The equivalent resistance of two 1 MΩ resistors in parallel is 500 kΩ. The equivalent capacitance of two 220 μF capacitors in parallel is 440 μF. The time constant is RxC = 440 x 10^-6 x 500 x 10⁵ = 220 s.

One time constant is the term for the time required for the capacitor in an RC circuit to be charged to 63.2% of the applied voltage. (E5B01) Similarly, one time constant is the term for the time it takes for a charged capacitor in an RC circuit to discharge to 36.8% of its initial voltage. (E5B02)

The capacitor in an RC circuit is discharged to 13.5% of the starting voltage after two time constants. (E5B03) Similarly, a capacitor charges to 86.5% of the applied voltage after two time constants.  After three time constants, a capacitor is charged up to 95% of the applied voltage or discharged to 5% of the starting voltage.

You can use these percentages to answer the questions about how much time it takes for a capacitor to discharge. The key is to figure out what percentage the voltage given is of the starting voltage. In one case, the starting voltage is 20 V and you must figure out how much time it will take for the capacitor to discharge to 7.36 V.

Well, 7.36 V just happens to be 36.8% of 20 V, so the time required will be one time constant. One time constant is R x C, or in this case 0.01 x 10^-6 x 2 x 10⁶, or .02 s. So, it takes 0.02 seconds for an initial charge of 20 V DC to decrease to 7.36 V DC in a 0.01-microfarad capacitor when a 2-megohm resistor is connected across it. (E5B05)

In the second case, the starting voltage is 800 V and you must calculate the time required for the voltage across the capacitor to drop to 294 V. Well, fortunately, 294 V / 800 V is again 36.8%, so the time required will be one time constant.

In this circuit, R = 1 MΩ and the capacitance 450 μF. R x C = 10⁶ x 450 x 10^-6 = 450 s. So, it takes 450 seconds for an initial charge of 800 V DC to decrease to 294 V DC in a 450-microfarad capacitor when a 1-megohm resistor is connected across it. (E5B06)

A high-pass filter can be made using two capacitors connected between the input and output and a shunt inductor. The cutoff frequency depends on the values of the components.

This particular filter has the characteristic of being a high-pass filter. That is to say it will pass frequencies above a certain frequency, called the cutoff frequency, and block frequencies below that frequency. A T-network with series capacitors and a parallel shunt inductor has the property of it being a high-pass filter. (E7C02) The reason the circuit acts this way is that as the frequency of a signal increases, capacitive reactance decreases and inductive reactance increases, meaning that lower-frequency signals are more likely to be shunted to ground.

A circuit containing capacitors and inductors can also form a low-pass filter. A low-pass filter is a circuit that passes frequencies below the cutoff frequency and blocks frequencies above it.

The circuit shown in figure E7C-2 is called a pi filter because it looks like the Greek letter pi. The capacitors and inductors of a low-pass filter Pi-network are arranged such that a capacitor is connected between the input and ground, another capacitor is connected between the output and ground, and an inductor is connected between input and output. (E7C01) The reason the circuit acts this way is that as the frequency of a signal increases, capacitive reactance decreases and inductive reactance increases, meaning that higher-frequency signals are more likely to be shunted to ground.

A low-pass filter is made from two shunt capacitors and a series inductance.

Pi networks can also be used to match the output impedance of one circuit to the input impedance of another or the output impedance of a transmitter to the input impedance of an antenna. An impedance-matching circuit transforms a complex impedance to a resistive impedance because it cancels the reactive part of the impedance and changes the resistive part to a desired value. (E7C04) One advantage of a Pi matching network over an L matching network consisting of a single inductor and a single capacitor is that the Q of Pi networks can be varied depending on the component values chosen. (E7C13)

A Pi network with an additional series inductor on the output describes a Pi-L network used for matching a vacuum-tube final amplifier to a 50-ohm unbalanced output. (E7C12) One advantage a Pi-L-network has over a Pi-network for impedance matching between the final amplifier of a vacuum-tube transmitter and an antenna is that it has greater harmonic suppression. (E7C03)

While transistor theory is outside the scope of this study guide, I will attempt to at least give you a basic understanding of how transistors are put together and how they work.  Most transistors we use in amateur radio are made of silicon. Silicon is a semiconductor. That is to say, it’s neither a conductor with a very low resistance, like copper, or an insulator with a very high resistance, like plastic or glass.

You can manipulate the electrical characteristics of silicon by adding slight amounts of impurities to a pure silicon crystal. When transistor manufacturers add an impurity that adds free electrons to the silicon crystal, it creates a crystal with a negative charge. We call that type of silicon N-type silicon. N-typeis a semiconductor material that contains excess free electrons. (E6A02) Free electrons are the majority charge carriers in N-type semi-conductor material.

When you add other types of impurities to a pure silicon crystal,  you can create a crystal with a positive charge. We call this type of material P-type semiconductor material. In N-type semiconductor material, the majority charge carriers are the free electrons. (E6A16) The majority charge carriers in P-type semiconductor material are called holes. (E6A03) P-type is the type of semiconductor material that contains an excess of holes in the outer shell of electrons. (E6A15)

You can think of holes as spots in the crystal that accepts free electrons. Because of that, the name given to an impurity atom that adds holes to a semiconductor crystal structure is call an acceptor impurity. (E6A04)

Silicon isn’t the only semiconductor material used to make transistors. At microwave frequencies, gallium arsenide used as a semiconductor material in preference to germanium or silicon. (E6A01)

Resources

• How Semiconductors Work
• P-type and N-type silicon

Amateur radio operators use many different ways to get signals from one spot to another. Perhaps one of the most interesting is meteor scatter propagation.

Meteor scatter propagation is possible because when a meteor strikes the Earth’s atmosphere, a cylindrical region of free electrons is formed at the E layer of the ionosphere. (E3A08) 28 – 148 MHz is the frequency range that is well suited for meteor-scatter communications. (E3A09)

Unfortunately, these ionization trails are relatively short-lived, so to communicate via meteor scatter, you need to either be able to detect when these paths are available or be transmitting when the paths are available. All of these choices are correct when talking about  good techniques for making meteor-scatter contacts (E3A10):

• 15 second timed transmission sequences with stations alternating based on location
• Use of high speed CW or digital modes
• Short transmission with rapidly repeated call signs and signal reports

For more information on meteor scatter, go to:

• G3WZT’s Meteor Scatter page
• RSGB’s Meteor Scatter page

Perhaps the most common danger is from RF exposure. The dangers from RF exposure differ from those posed by exposure to radioactive materials. What, if any, are the differences between the radiation produced by radioactive materials and the electromagnetic energy radiated by an antenna? Radioactive materials emit ionizing radiation, while RF signals have less energy and can only cause heating. (E0A01)

The amount of heating is proportional to the specific absorption rate (SAR). SAR measures the rate at which RF energy is absorbed by the body. (E0A08) OIn general, the SAR increases as the frequency increases. Localized heating of the body from RF exposure in excess of the MPE limits is an injury that  can result from using high-power UHF or microwave transmitters. (E0A11) One of the potential hazards of using microwaves in the amateur radio bands is that the high gain antennas commonly used can result in high exposure levels. (E0A05)

The FCC, as you might expect, has a lot to say about RF exposure. They have set limits on the field strengths that humans may be exposed to. These limits are called maximum permissible exposure, or MPE.

The MPEs for the electric field and magnetic field of an electromagnetic wave differ. All of these choices are correct as to why there are separate electric (E) and magnetic (H) field MPE limits (E0A06):

• The body reacts to electromagnetic radiation from both the E and H fields
• Ground reflections and scattering make the field impedance vary with location
• E field and H field radiation intensity peaks can occur at different locations

One way to make sure that the field strengths that your transmissions expose you and others to is to measure the absolute field strengths. Unfortunately, this is not easy to do. The equipment used to measure field strength is very expensive and difficult to use. An alternative is to use software that calculates field strength. Using an antenna modeling program to calculate field strength at accessible locations would be a practical way to estimate whether the RF fields produced by an amateur radio station are within permissible MPE limits. (E0A03)

Remember to include your neighbors when evaluating RF exposure levels. In some cases, your antennas may actually be closer to your neighbors’ houses than they are to your house. When evaluating RF exposure levels from your station at a neighbor’s home, you must make sure signals from your station are less than the uncontrolled MPE limits. (E0A02)

Typically, amateur repeater stations are located in places where there are transmitters for other radio services, such as cell phone and pager services. These sites should be regularly evaluated so that RF field strengths don’t exceed the MPE limits. When evaluating a site with multiple transmitters operating at the same time, the operators and licensees of each transmitter that produces 5% or more of its MPE exposure limit at accessible locations are responsible for mitigating over-exposure situations. (E0A04)

RF exposure is not the only danger posed by an amateur radio station. For example, in emergency situations, you may want to use a gasoline-powered generator. One of the dangers posed by a gas-powered generator is that its exhaust contains carbon monoxide. Dangerous levels of carbon monoxide from an emergency generator can be detected only with a carbon monoxide detector. (E0A07)

Some of the materials used in electronics pose a danger to amateur radio operators. They are used because they have some desirable electrical property, but may be dangerous if used improperly. For example, beryllium oxide is an insulating material commonly used as a thermal conductor for some types of electronic devices that is extremely toxic if broken or crushed and the particles are accidentally inhaled. (E0A09) Polychlorinated biphenyls, or PCBs, is a material found in some electronic components, such as high-voltage capacitors and transformers, that is considered toxic. (E0A10)