Element 2 - Technician - Supplemental Material

This is some supplemental material to help one study specifically for the Element 2 (Technician) exam, although the concepts have universal applicability. If you find inaccuracies, or have suggestions for improvement, please notify the author.

RST - Readability, Strength, Tone

RST is the amateur radio short-hand for signal reporting, commonly provided by most radio contacts. For CW (Morse code via Continuous Wave), use all three values; a perfect signal would be "RST 599". For phone, use only the first two values; a perfect signal would be "RST 59".

R - Readability	S - Strength	T - Tone Quality (CW only)
5 - Perfectly readable; 100% copy	9 - Extremely strong signal	9 - "Pure" tone
4 - Mostly readable; 75% copy	7 - Strong signal	7 - Slight ripple; slight variation in tone
3 - Somewhat readable; 50% copy	5 - Good signal	5 - Smooth ripple; variation in tone; slight chirp or click
2 - Barely readable; 25% copy	3 - Weak signal	3 - Ripple; strong tone variation; click or chirp
1 - Not readable; few words or letters at most	1 - Faint signal; near noise threshold	1 - Rough ripple or raspy tone; strong click or chirp

Note: the numbers "in between" (i.e., S8, S6, T8, etc.) are intermediate values, and in practical terms are less commonly used. Sometimes, especially in contests, some of the numbers are abbreviated — most commonly, '9' becomes 'N': "… RST 5NN …"

International Phonetic Alphabet

Over the years there have been many standard phonetic alphabets. ("The wonderful thing about standards is that there are so many to choose from.") There are, of course, other words that begin with these same letters, but the use of "cute" phonetics is discouraged, as they might confuse those in your geographic area, and will confuse those who speak a different language. Just use these.

Note: certain of the phonetic words use international English pronunciation — which usually means softening (dropping) the (strong American) 'R' sound; the provided pronunciations are more understandable to non-English speakers. Also note the lack of the "kw-" sound in Quebec, and the emphasis on Papa.

Repeater Systems (VHF/UHF)

Repeater systems include, among other things, both a receiver and a transmitter operating in duplex mode. (Contrast to Simplex Communication.) The repeater system controller passes the audio out from the receiver to the audio input of the transmitter. The receiver and transmitter operate simultaneously on two separate frequencies (duplex), usually within the same band. In effect, it "repeats" everything you transmit, hence the name.

Repeater systems are usually placed on mountaintops, or failing available mountainous locations, on tall buildings, water towers, or tall radio towers, etc. This is to provide extended line-of-sight to inaccessible areas (either side of the mountain in the diagram), and provide an extended coverage area (right side of diagram), especially for those with weak, or low-power signals.

Repeater System

Repeater systems have an input and an output frequency. The system receives signals on its input frequency, and retransmits the audio on the output frequency. The separation between the input and output frequencies is called the offset. Each VHF/UHF band has a standard offset defined; the offsets for the three most common VHF/UHF bands are

Band (frequency)	Wavelength	Offset
144 - 148 MHz	2 meters	600 kHz (0.600 MHz)
222 - 225 MHz	1¼ meters	1.6 MHz (1600 kHz)
420 - 250 MHz	70 centimeters	5.0 MHz

Most modern transceivers display the output frequency of the repeater system (the frequency your transceiver listens on), and shifts by the offset amount to the repeater system's input frequency for transmission to the repeater system. Depending on the location within the band-plan, the offset will be either positive (repeater system's input above the output frequency) or negative (repeater system's input below the output frequency).

Simplex Communication

Simplex means "one-way at a time" as contrasted to duplex, which means "two-ways at a time." In terms of radio communications, simplex means using one frequency. A group of two or more operators take turns sharing that one frequency; one station transmits, but cannot receive during transmission; the other stations receive, but cannot transmit lest they interfere with the transmitting station. If more that one station transmits when using FM, both transmissions will likely be garbled. This is often referred to as "doubling", or as "covering" a transmission.

If you are in contact with another station through a repeater system, you can easily determine if you could use simplex communication instead. Most radios have a rev ("Reverse") or mon ("Monitor") function that temporarily switches to the input frequency of the repeater, which is the frequency that the other station would be transmitting on. If you can copy the other station "on the reverse", you could change to a simplex frequency to continue your contact without tying up the repeater system.

Dipole Antenna — As Simple As It Gets

Dipole Antenna

A dipole antenna has two equal length wires, connected in the middle to a feed-line, typically coaxial cable (coax). The overall length of a resonant dipole is one-half wavelength (½ λ) from end to end. Depending on the height of the dipole elements, the feed-point impedance is between 45- and 72-Ω (ohms).

An inexpensive dipole can be made with regular wire that is strong enough to withstand the tension. The center of the dipole requires some form of insulator to separate the two wires. The far ends of the dipole needs an insulator, and is typically hooked to rope, which is then tied to tall trees, poles, etc. If you can support the center of the dipole, then the tension on the wire and ropes will be lessened.

As an example, for a 40 meter dipole we choose a frequency near the center of the phone portion of the band (7.2 MHz), which allows us to use SSB (phone), and still be able to operate CW, too. Divide that frequency into the magic value of 468, and find that our dipole should have a total length of 65 feet. Each element should be half that length. For best results, cut your wire just a bit longer, and trim as necessary to achieve best SWR results across the band.

Propagation Types

Long distance propagation of Radio Frequency (RF) waves is cause primarily by ionization of the upper atmosphere, known as the ionosphere. A secondary cause for RF propagation is the electromagnetic field surrounding the earth.

The Ionosphere

Ionospheric Layers

The ionosphere has three primary layers, the D, E, and F layers. These layers are caused by ultra-violet radiation from the sun ionizing the upper atmosphere. During daylight hours, the D and E layers energize, and the uppermost region, the F layer, bifurcates into the F1 and F2 layers. After the sun sets, the D and E layers fade, and the F1 and F2 layers recombine.

The nearest layer, the D layer, is mostly responsible for dampening most signals during the day, especially during the afternoon and during the summer. Some low-frequency RF energy will "bounce" back to earth from the D layer. The D layer is between 25 and 55 miles up.

The E layer is also a daytime layer. It is often referred to as the "eccentric" layer; sometimes you can get great 10 and 6 meter propagation from this layer. Propagation via the E layer is usually referred to as Sporadic E propagation. The E layer is between 55 and 90 miles up.

The F layer — specifically the F2 layer (during daylight hours) — is the layer primarily responsible for long-distance propagation. During the daylight hours, this layer splits into the F1 and F2 layers. The F layer (night-time) is between 90 and 250 miles up; the F1 layer (day-time) is between 90 and 150 miles up; the F2 layer (day-time) is more than 250 miles up.

Line-of-Sight

Radio signals travel more or less in a straight line. This is known as line-of-sight propagation. VHF and UHF signals normally do not reflect off the ionosphere, so "what you see is what you get." Often the real fun of amateur radio is finding the exceptions to this rule. It can be amazing how good mountains are at reflecting radio signals. Also interesting is how far you can communicate from a mountain-top, or mountain-top to mountain-top.

Ground-wave

Ground-wave Propagation

A portion of all radio signals hugs the curvature of the Earth, traveling along the ground. This type of propagation is known as ground-wave propagation. Radio waves don't travel very far, and it usually requires lower frequencies (HF) and lots of power for this type of propagation to be of much use. For VHF and UHF purposes, ground-wave propagation extends line-of-sight beyond the horizon by up to 15%.

Sky-wave

Sky-wave Propagation

VHF and UHF radio signals normally don't go very far beyond the horizon, as far as line-of-sight is concerned. VHF and above is also too energetic to be reflected by the ionosphere. However, 6-meter and HF radio signals can often be reflected by the ionosphere to more distant locations.

Skip Zone

Beyond the range of ground-wave propagation, and before sky-wave propagation becomes usable, there is a "dead" zone, as far as radio wave propagation for a given frequency. This zone is called the skip-zone. Sometimes communication into the skip-zone can be effected by means of sporadic-E and scatter from NVIS type signals.

Voltage, Current, Resistance, Power

Voltage (E, volts (V)), Current (I, amps (A)), Resistance (R, ohms (&Omega)), and Power (P, watts (W)) are all related; use these easy mnemonic circles to remember the relationships:

These two circles represent Ohm's law (E = I × R), and the Power law (P =I × E).

To find the formula for any one element, simply cover the value you're looking for with your finger. The uncovered portions of the mnemonic will then show you the formula you need to use to calculate the value you're after. By using both circles together you can find any of the four values from just two of the others; in some cases both circles will be required.

Example 1

A. To find the Voltage (E) given Current (I) and Resistance (R), cover the unknown Voltage (E), which leaves Current (I) times Resistance (R).

Example 2

A. To find the Current (I) given Voltage (E) and Resistance (R), cover the unknown Current (I), which leaves Voltage (E) divided by Resistance (R).

Example 3

A. To find the Resistance (R) given Voltage (E) and Current (I), cover the unknown Resistance (R), which leaves Voltage (E) divided by Current (I).

Example 4

A. To find the Power (P) given Voltage (E) and Current (I), cover the unknown Power (P), which leaves Voltage (E) times Current (I).

Example 5

Q. How many amps are drawn by a 100 W light bulb in your home? (Hint: your house wiring is 120 volts.)

A. To find the Current (I) given Power (P) and Voltage (E), cover the unknown Current (I), which leaves Power (P) divided by Voltage (E).

Example 6

Q. If your 100-watt transmitter is driving a 50-ohm load, what is the minimum voltage potential that your feed line has to be able to handle?

A. We're looking for Voltage (V), given Power (P) and Resistance (R). We're going to need both circles to solve this problem. First let's start with Power (P):

We don't know E or I, so we need to use the other circle now. Since we're trying to find Voltage (E), let's solve for Current (I) so we can eliminate that from our first equation:

A	- Alpha	G	- Golf	M	- Mike	S	- Sierra	Y	- Yankee
B	- Bravo	H	- Hotel	N	- November	T	- Tango	Z	- Zulu
C	- Charlie	I	- India	O	- Oscar (AW-ska)	U	- Uniform
D	- Delta	J	- Juliet	P	- Papa (pa-PA)	V	- Victor (VIC-tah)
E	- Echo	K	- Kilo	Q	- Quebec (keh-BEK)	W	- Whiskey
F	- Foxtrot	L	- Lima	R	- Romeo	X	- X-Ray

Supplemental Material for Element 2 - Technician