Pass Your Amateur Radio Technician Class Test - The Easy Way by Radio K4IA

Author:Radio K4IA
Language: eng
Format: mobi
Published: 2016-03-05T22:00:00+00:00

9 Field Day is an annual exercise the last full weekend in June. Hams go to the field and operate with emergency power seeing how many contacts they can make. My personal goal is 1000 contacts in 24 hours. It is a combination of club picnic, campout and operating. Check with your local club. They are bound to have something planned and will welcome you.

An ARQ transmission system detects errors and sends a request to retransmit. (Automatic Repeat Query). If the numbers don’t add up, the receiving station automatically asks for a repeat.

The error rates will increase if the signal is arriving on multi-path (meaning the signal has bounced off several different places and has therefore become several different signals arriving at slightly different times). The computer will dutifully keep trying until it gets it right.

APRS is another use for packet. APRS means Automatic Packet Reporting System. APRS works in conjunction with a map showing the location of stations.

Data to the transmitter for automatic position reports is supplied by a GPS Global Positioning System receiver. The GPS sends your location to a TNC (Terminal Node Controller) connected to the radio and the radio broadcasts your position over a packet network. Others can receive the information and read your location from a computer generated map.

The packet network is made up of digipeaters, digital repeaters. A digipeater operates on automatic control. It is a repeater.

Your computer sound card also generates PSK, which stands for Phase Shift Keying. PSK31 is a low rate (slow) digital mode. A PSK signal will trot across your screen about as fast as most of us can type. Your computer can decode PSK signals that are barely audible. As a Technician, you have data privileges on 10 meters and can operate worldwide PSK there.

The presence of a signal is determined by the receiver’s sensitivity. A receiver’s selectivity is the ability to discriminate between signals. These two goals conflict as the first part of the receiver is designed to be sensitive to a wide range of frequencies (sensitivity). Then, you need to narrow what you hear (selectivity).

To accomplish selectivity you first convert the incoming signal to an intermediate frequency using a mixer. Then, filtering stages are designed to operate on that one intermediate frequency and provide selectivity.

It all starts with an oscillator – the circuit that generates a signal at a desired frequency.

Then, you convert a signal from one frequency to another with a mixer. On the transmit side, you convert a low powered 28 MHz exciter to 222 MHz output using a transverter. This is a type of mixer. It is called a “transverter” because it also transmits. The keywords here are “exciter and output.” That tells us you are converting a transmitter, thus a transverter. Cheat: If you see transverter in an answer, it is always right.

Ignition noise is a pop-pop sound coming from the spark system of your car or one driving by. Ignition noise might go away if you turn on the noise blanker.

Another receiver circuit is called AGC – Automatic Gain Control keeps the received audio relatively constant.

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