Difference between revisions of "Ham Radio Exam Questions- General"

Latest revision as of 17:53, 11 November 2015

General Class

Question examples. These are the kind of questions that you will find in the examination.

Q: How are the two separate frequencies of a Frequency Shift Keyed (FSK) signal identified?

A: Mark and Space

Q: Which of the following is an advantage of an NVIS antenna?

A: High vertical angle radiation for working stations within a radius of a few hundred kilometers

Q: What receiver stage combines a 14.250 MHz input signal with a 13.795 MHz oscillator signal to produce a 455 kHz intermediate frequency (IF) signal?

A: BFO

Q: When may an amateur station transmit communications in which the licensee or control operator has a pecuniary (monetary) interest?

A: When other amateurs are being notified of the sale of apparatus normally used in an amateur station and such activity is not done on a regular basis

Q: At what point in the solar cycle does the 20-meter band usually support worldwide propagation during daylight hours?

A: At any point in the solar cycle

Q: Which of the following is an advantage of a switchmode power supply as compared to a linear power supply?

A: High frequency operation allows the use of smaller components

Q: What is the frequency deviation for a 12.21 MHz reactance modulated oscillator in a 5 kHz deviation, 146.52 MHz FM phone transmitter?

A: 416.7 Hz

background

FSK

FSK is commonly used for caller ID and remote metering applications. FSK is also known as frequency modulation (FM). You will often hear the terms FSK and AFSK when talking about RTTY on the HF bands. FSK means Frequency Shift Keying and AFSK means Audio Frequency Shift Keying. MARK is always the higher RF frequency and SPACE is always the lower RF frequency.

NVIS

An NVIS antenna (Near vertical incidence skywave) is a horizontally polarized radiating element that is from 1/20th wavelength (λ) to 1/4 wavelength above the ground.

ALC on SSB

Automatic Level (Linearity) Control. This is used to reduce distortion by control of the signal strength going into the power amplifier in the transceiver. Amplifier drive is controlled by the ALC by use of an adjustable negative-going DC voltage which is fed back to the transceiver. You adjust the ALC to match your own speech, which is to say how loud you talk into the microphone, your distance from the mic, etc, to arrive at the most efficient way to deliver power without distortion. Adjust the transmit power and microphone gain and use an ALC meter to determine optimal performance settings.

PEP

Peak envelope power (PEP) is the highest envelope power supplied to the antenna. This max power is at the peek of the waveform, something not detectable with a typical power meter. PEP is best determined using an oscilloscope.

MUF

Maximum Usable Frequency. Operational MUF is the highest frequency you can operate with your specific working conditions and equipment to communicate with another specific station. MUF is dependent on ionospheric radio propagation. Frequencies including the Critical Frequency; Lowest Usable Frequency, LUF; Maximum usable frequency, MUF; and the Optimum Working Frequency, OWF are all relevant when determining which frequencies will provide the best performance for a short wave radio, and HF 2-way radio communications. Know your international / DX beacons that you can tune to so that you can determine the current MUF.

S-meter

When asked to give a signal report you look at the signal strength meter which is also known as the S-meter. The S-meter allows you to determine 1 of the 3 values of RST. Nearly all radio receivers have an S-meter.

BFO

Used for CW. A beat frequency oscillator or BFO , is a dedicated oscillator used to create an audio frequency signal from Morse code radiotelegraphy (CW) transmissions to make them audible.

Winlink

A radio messaging system that mixes Internet and ham radio. Email via High frequency (HF) is made possible by connecting an HF single sideband (SSB) transceiver system to a computer, modem interface, and software. It uses a commercial modem to provide HF email which some say should not be allowed on HF.

Keyed Connector

The most common type of connector keying employs notches to direct the connectors together. XLR connectors, for example, have a tiny notch on the top left side for female connectors and the top right side for male connectors. This is so you don't stick the wrong type of plug into the socket. Keyed connectors may use notches, grooves, bumps, bulges, and blips.

Short Path and Long Path propagation

F Layer propagation types

• Long Path Propagation
• Grey-Line Propagation
• Backscatter

reactance-modulated oscillator

There are a couple ways of producing an FM signal on the 2 meter band. It is inexpensive to use a quartz crystal oscillator however it cannot produce such a high frequency. So a lower frequency is used, then that is multiplied to get to the desired higher frequency. It might look something like this:

12.21MHz * 2 = 24.42MHz, 24.42MHz * 2 =48.84MHz, 48.84 * 3 = 146.52MHz

Again, the multiplier method of generating a FM signal is less expensive than using a heterodyne system.

When talking about a total deviation at the final frequency of 5kHz then consider we arrive at that number (5kHz) the same way we multiplied to arrive at our target frequency of 146.52MHz.

416.7Hz * 2 = 833.4Hz, 833.4Hz * 2 = 1666.8Hz, 1666.8Hz * 3 = 5000.4Hz which rounds to 5kHz

PACTOR protocol

A radio modulation mode used to send and receive digital information via radio. PACTOR is an evolution of both AMTOR and packet radio. PACTOR is a set of standardized modes used by Amateur operators for FSK radioteletype transfer of digital information over HF. A PACTOR communication is between two stations only.