Frequencies for the Technician

Here's a list of the bands that a ham with a technician license can use. Within each band is a band plan that the community has devised to dictate what you can do with what frequencies within the band.

80 meters

• 3525-3600 kHz: CW Only
  

40 meters

• 7.025-7.125 MHz: CW Only
  

15 meters

• 21.025-21.200 MHz: CW Only
  

10 meters

• 28.000-28.300 MHz: CW, RTTY/Data w/ maximum power 200 watts PEP
  
• 28.300-28.500 MHz: CW, Phone w/ maximum power 200 watts PEP
  

6 meters

• 50.0-50.1 MHz: CW Only
• 50.1-54.0 MHz: Phone, Image, MCW, RTTY/Data

2 meters

• 144.0-144.1 MHz: CW Only
• 144.1-148.0 MHz: CW, Phone, Image, MCW, RTTY/Data

1.25 meters

This band is to be used on a secondary basis. The Automated Maritime Telecommunications Systems stations have primary use. There are also power restrictions and notification procedures to go through before you can use this band. Do some research first.

• 222.00-225.00 MHz: CW, Phone, Image, MCW, RTTY/Data

70 centimeters

• 420.0-450.0 MHz: CW, Phone, Image, MCW, RTTY/Data

33 centimeters

• 902.0-928.0 MHz: CW, Phone, Image, MCW, RTTY/Data

23 centimeters

• 1240-1300 MHz: CW, Phone, Image, MCW, RTTY/Data

Sources:

http://www.hamuniverse.com/frequencyallocations.html
http://en.wikipedia.org/wiki/Amateur_radio_frequency_allocations
http://www.arrl.org/frequency-allocations

Q Signals

Here's a post that's mostly for my own studies, but I hope others will find it useful. Today's topic is Q signals.

The Q signals is radio shorthand. Each Q abbreviates common phrases and allows operators who speak other languages to communicate without learning English. They can be used as questions or as answers. For example, you can ask "QRN?" to see if anyone is getting static from you. An answer could be "Getting a little QRN from you."

Common Q Signals

QRG: You exact frequency is ___ .
QRL: I am busy. Is the frequency busy?
QRM: Getting interference on your transmission.
QRN: I'm getting static.
QRO: Increase power.
QRP: Decrease power.
QRU: I have nothing else. Sign off.
QRV: I am ready.
QRX: I will call you again in ___ at ___ kHz.
QRZ: You are being called by ____ on ____ kHz.
QSB: Your signal is fading.
QSK: I can hear you when not transmitting.
QSL: Receipt acknowledged.
QSO: I can communicate with ____ direct ( or by relay ).
QSP: I will relay to ___.
QST: Call to all amateur radio operators.
QSX: I am listening to ___ on ___ kHz.
QSY: Change to transmission on ___ kHz.
QTC: I have ___ messages for you.
QTH: My location is ___.
QTR: The time is ___.

Basic Operation of Transmitter and Receiver

Here's a post that's mostly for my own studies, but I hope others will find it useful. Today's topic is basic operation of a transmitter and receiver.

A dual-band transceiver works on the 2-meter and 70-cm bands. A multi-band transceiver works on higher HF bands. In either case, the first thing the operator does is to select the band over which he is to transmitter or receive. From inside the band, the operator uses the variable frequency oscillator (VFO) to select the frequency. The tuning rate may be adjustable on a radio so that discreet movements in the VFO change the frequency more or less quickly. Some radios have a keypad to punch in the desired frequency.

On multi-mode radios, the operator must also select the signal mode - AM, SSB, USB, LSB, FM, CW, Data. Most wideband rigs are multi-mode.

Memories or memory channels allow the operator to store settings for later use. These settings include frequency and mode but may also include power level and access tones.

The RF power control changes the maximum transmitter output power. Some handhelds include a set of fixed levels for recall. The microphone gain control also affects transmitter output though adjusting the sensitivity of the microphone. Frequency or amplitude can be overmodulated to cause distortion in the signal.

The speech compressor or speech processor raises the low levels of transmit signal more than the strong parts. This makes for a more uniform waveform that improves reception. Too much compression can cause distortion or loss of interference.

Peak envelope power (PEP) measures the loudest that speech gets on an AM or SSB signal.

A dummy load absorbs all the energy from a station so that adjustments can be made to the radio without actually broadcasting.

A transmitter only transmits if it is keyed through a push-to-talk (PTT) or voice-operated transmission (VOX) function. Since VOX automatically keys the transmitter, several controls are available to adjust the level of sensitivity -- gain, delay, anti-vox.

Overmodulation can cause distortion or spurious outputs on adjacent frequencies. In general, this is called splattering. Speaking softly often reduces overmodulation. Automatic level control (ALC) automatically reduces power output when a certain output power limit is reached.

The AF gain is the volume control on a receiver. The RF gain on an HF rig controls the sensitivity of the receiver. The squelch circuit mutes the audio if no signal is present so that you're not listening to static. Band-pass filters allow the receiver to only listen to certain frequencies. A notch filter removes a narrow range of frequencies. Noise blankers remove sharp noises and mute them. Noise limiters attenuate the sound so you don't get blasted with sound if lightning strikes and other spikes.

S-units measure the signal strength and is measures from S-1 to S-9.

Sweeping looks through presets for activity. Scanning jumps through frequencies.

Repeaters have a standard offset (or shift) between output and input frequencies. This means you only have to remember the output frequency to know what the input frequency is. Offsets can be positive or negative for 2-m and 70-cm bands. Repeaters are referenced by their output frequency.

Repeaters also have access tones that tell it that the signal needs to be retransmitted. These tones are called continuous tone coded squelch system (CTCSS), private line (PL), or subaudible. GMRS and FRS radios have the same thing called privacy codes. Radios have tone keys that automatically send the CTCSS tones when the mic is keyed.

Data conversion can often be done with software and a sound card, though some sort of radio control interface is required for the computer. An Internet gateway connects the radio network to the Internet. No money-making over the radio network; this includes ads on webpages!

Waves

Here's a post that's mostly for my own studies, but I hope others will find it useful. Today's topic is waves.

AC signals are described using a sine wave (from high school geometry). Anything above 0 on the typical graph is positive and below is negative. One full cycle of a sine pattern is called the cycle. The number of cycles per second is the frequency, which is measured in Hertz (Hz). The inverse of the frequency is the period, which is measured in seconds. For example, a wave with a frequency of 3 Hz cycles 3 times per second; it also has a period of 1/3 seconds.

The wavelength of a wave is the distance that is has traveled in one cycle. Wavelength is usually measured in meters and is represented by the Greek lambda (λ). Wavelength is the speed (usually the speed of light, c) divided by frequency. Remember that c is a constant, so we don't need to calculate for it.

λ = c / f
f = c / λ

We can use the old D=R*T equation from middle school on this one. The rate is c, which is the speed of light. The time is the period, which is the inverse of frequency, so, instead of multiplying by period, we can divide by frequency.

Since the speed of light is constant, it is common to have a wave talked about in terms of frequency or of wavelength. A 3MHz wave can be referred to as a 100m wave.

If capactive and inductive reactance cancel each other, you have resonance.

Radio frequencies: > 20kHz
Audio frequencies: <> 1GHz

A band is a range of frequencies used for a specific purpose. For example, the frequencies that ham operators use is called the amateur or ham bands.

The phase is the position with a cycle. If you are 180 degrees out of phase, you are out of phase.

Modulation is modifying a wave to by adding information to it.

In amplitude modulation (AM), the carrier wave is modified by the amplitude of the information it to create small peaks and valleys above the carrier wave. The carrier is then subtracted from the resulting wave to get the information out. This process is called demodulation. Any signal above the carrier wave is called the upper sideband (USB); any lower is the lower sideband (LSB). The sidebands contain the information!

If you had a 1MHz carrier and wanted to carry voice, what would the sidebands be? Voice goes up to about 3kHz, so, if you added and subtracted that from the 1MHz carrier, you would have a LSB of 997kHZ and a USB of 1003kHz (1.003MHz).

AM is very inefficient. Most of the power is dedicated to the carrier and two sidebands (which are mirrors of each other). A single sideband (SSB) is a signal with the carrier and one of the sidebands removed. This is much more efficient since the power is dedicated to the data and not the carrier or other sideband. UHF and VHF use the USB of the signal.

Modulation modes that change the frequency to add the information is frequency modulation (FM). When information is put on the carrier wave, the frequency deviates to include the information. Amplitude is not changed in FM transmission, making it a constant power signal. FM has many sidebands that range from 5 to 15 kHz. FM is popular because interference actually generates changes in amplitude, which can be filtered out with a limiter.

Modulation modes that change the phase of a wave when information is added is called phase modulation (PM).

Data can be transferred over the air by using data modes. A modem changes data to audible signals, and, on the other end, another modem demodulates. Protocols swch as RTTY, AX.25, B2F, PSK31, MFSK, AMTOR, and PACTOR all combine with a modulation to take care of errors and loss. A terminal node controller (TNC) is a microprocessor that processes the protocols along with a modem. A multiple protocol controller (MPC) is a TNC that does many protocols.

Electrical Components

Here's a post that's mostly for my own studies, but I hope others will find it useful. Today, we're studying electrical components and their functions.

Resistors control the flow of electrons (current, I) through a medium. Resistors are rated in terms of resistance in Ohms. A variable resistor is called a potentiometer or pot.

Capacitors store energy. Capacitors are rated in terms of Farads (F) such as picofarads (pF) or microfarads (uF). They smooth out changes in voltage and are compared to a water tower. A water tower stores water and serves it to the community until it slowly runs out of water or until more water is pumped into it. The same goes for capacitors and electrons. Capacitors have no effect on AC current since it will be constantly filling and emptying as the current changes directions.

Inductors store magnetic energy like a capacitor stores electrical energy. Inductors are rated in terms of Henries (H) such as millihenries (mH). They smooth out changes in current (capacitors smooth voltage changes). When current is placed onto an inductor, the coil forms a magnetic field that builds until it reaches the max inductance for the inductors. The inductor then releases current at a steady rate.

Resistance to AC current is called reactance (signified by X) and is measured in Ohms. Capacitors are said to have capacitive reactance; inductors are said to have inductive reactance. The combination of capacitance and reactance is generally referred to as impendence.

Diodes allow current to flow in only one direction. If AC current is applied to a diode, the result is a DC current.

Transistors are doped so that small changes in voltage or current control larger voltages and currents. In other words, they can act as amplifiers if patterned correctly.

Integrated circuits (IC or chip) are combinations of active and passive components packaged together to do a particular task. Microprocessors are ICs.

Fuses interrupt excessive current by physically breaking the connection. Breakers do the same, but, instead of blowing up or melting, they trip and can be reset.

Ground-fault interrupters (GFIs) trip of it senses a current difference between hot and ground. If you drop the hair dyer in the tub, the ground side of the GFI will have a drop in current (since all the electrons are pouring out into the water), and the GFI will trip.

Surge protectors become resistors if the voltage gets above a certain level. This eliminated transient spikes. Lightning arrestors do the same job as surge protectors but are designed to take much higher currents and voltages.

Schematics are diagrams that describe a circuit. They use circuit symbols that represent the components and how they are connected together. Each symbol has a designator to name each component, like R1, R2, R3, RN for the resistors.

Basic Electricity

Here's a post that's mostly for my own studies, but I hope others will find it useful.

Current is the flow of electrons. It is represented by the letter I. Current is measured in Amperes, which is represented by the unit A. Current is measured with an ammeter.

Voltage is the electro-motive force of electricity. It is represented by the letter E. Voltage is measured in Volts, which is represented by the unit V. Voltage is measured with a voltmeter. Voltage is measured from a reference voltage, which is usually ground. Voltage also has a polarity; positive polarity attracts electrons, while negative polarity repels them.

Resistance is the impedance of current. It is represented by the letter R. Resistance is measured in Ohms, which is represented by the unit Ω. Resistance is measured with an ohmmeter.

Ohm's Law defines the relationship among current (I), voltage (E), and resistance (R).

R = E / I

You can solve the equation for the others with some quick math.

E = R * I
I = E / R

Power is the product of voltage (E) and current (I). It is represented by the letter P. Power is measured in Watts, which is represented by the unit W. Power is not measured directly and must be calculated.

P = E * I

Again with some quick math.

E = P / I
I = P / E

Using the equations from Ohm's Law, we can substitute values for voltage (E) and current (I) in to the Power equation. Since E = R * I, we can say that P = (R * I) * I or RI^2. Also, since I = E / R, P = E * ( E / R), or E^2/R.

P = E^2 / R
P = R * I^2

Introductions

Hi. My name is Aaron, and I'm taking some time off from my career studies to get my ham radio licenses. I have a blog on networking stuff at my own place which I use to make study notes, so, as I go through my studies here, I thought I would do the same.

Naturally, I'm going to start with the technician license, so keep an eye out for the basic stuff that all you Elmers already know. For the record, I just read the term "Elmer" in a book and have no clue when to use it appropriately. :)

Talk to you guys on the air soon. I'm sure my jargon will be better in time.