Amateur Radio for Smart People
What is the typical output impedance of an integrated circuit op-amp? [E7G15] A. Very low B. Very high C. 100 ohms D. 1000 ohms A A. Very low output impedance is a property of an IC op-amp. In an ideal case, it would be zero. But of course that’s never possible. In reality, the behavior … Read more
What is the frequency deviation for a 12.21 MHz reactance modulated oscillator in a 5 kHz deviation, 146.52MHz FM phone transmitter? [G8B07] A. 101.75 Hz B. 416.7 Hz C. 5 kHz D. 60 kHz Whoa, what? Guess what, dust off that calculator, because here’s where it starts to get mathy. This question is also terribly … Read more
Which of the following describes a simple dipole mounted so the conductor is parallel to the Earth’s surface? [T9A03] A. A ground wave antenna B. A horizontally polarized antenna C. A rhombic antenna D. A vertically polarized antenna Lets recall what we mean when we talk about an electromagnetic field being “polarized.” The direction of … Read more
What type of wave is made up of a sine wave plus all of its odd harmonics? [E8A01] A. A square wave B. A sine wave C. A cosine wave D. A tangent wave Well, the answer to this question is mathematically somewhat complex. The answer is A. A square wave. Rather than try and … Read more
Which type of code is used for sending characters in a PSK31 signal? [G8C12] A. Varicode B. Viterbi C. Volumetric D. Binary Alright, here we are again at a real head scratcher. This is yet another example of something you just “need to know” for the test. In real life you really wouldn’t use this … Read more
If a frequency readout shows a reading of 2425 MHz, what frequency is that in GHz? [T5B13] A. 0.002425 GHZ B. 24.25 GHz C. 2.425 GHz D. 2425 GHz The best way to figure this out is to review our metric prefixes. If you’re into computers at all, you already use “Mega” and “Giga” and … Read more
What do the letters in a satellite’s mode designator specify? [E2A05] A. Power limits for uplink and downlink transmissions B. The location of the ground control station C. The polarization of uplink and downlink signals D. The uplink and downlink frequency ranges Lets look at “mode designators” to understand what the question is about. A … Read more
How should the winding axes of two solenoid inductors be oriented to minimize their mutual inductance? [G6A19] A. In line B. Parallel to each other C. At right angles to each other D. Interleaved The best way to answer this is to imagine the magnetic field lines coming off of a device, much like in … Read more
What are the two components of a radio wave? [T3B03] A. AC and DC B. Voltage and current C. Electric and magnetic fields D. Ionizing and non-ionizing radiation This is a “definition” type of question, one that if I remember correctly was posed to us on day one of my college Electromagnetics class. A “radio … Read more
Digital modes are the topic of this week’s Amateur Extra exam question…. [E8C13] What is one advantage of using JT-65 coding? A. Uses only a 65 Hz bandwidth B. The ability to decode signals which have a very low signal to noise ratio C. Easily copied by ear if necessary D. Permits fast-scan TV transmissions … Read more
