Amateur Extra

Which insulating material commonly used as a thermal conductor for some types of electronic devices is extremely toxic if broken or crushed and the particles are accidentally inhaled? [E0A09] A. Mica B. Zinc oxide C. Beryllium Oxide D. Uranium Hexaflouride The answer is C. Beryllium Oxide.  One of the hazards we face as radio enthusiasts … Read more

Which of the following would be a practical way to estimate whether the RF fields produced by an amateur radio station are within permissible MPE limits? [E0A03] A. Use a calibrated antenna analyzer B. Use a hand calculator plus Smith-chart equations to calculate the fields C. Use an antenna modeling program to calculate field strength … Read more

What is the advantage of including a parity bit with an ASCII character stream? [E8C12] A. Faster transmission rate B. The signal can overpower interfering signals C. Foreign language characters can be sent D. Some types of errors can be detected The definition of a “parity bit” according to Wikipedia is: a bit added to … Read more

Which of the following digital modes is especially useful for EME communications? [E2D03] A. FSK441 B. PACTOR III C. Olivia D. JT65 Due to the time it takes for signals to get to the moon and back, (EME = Earth-Moon-Earth) we need a mode that is highly dependent on time synchronization.  This way everyone knows … Read more

What do the two numbers represent that are used to define a point on a graph using rectangular coordinates? [E5C11] A. The magnitude and phase of the point B. The sine and cosine values C. The coordinate values along the horizontal and vertical axes D. The tangent and cotangent values This might seem like a … Read more

What happens to reactive power in an AC circuit that has both ideal inductors and ideal capacitors? [E5D09] A. It is dissipated as heat in the circuit B. It is repeatedly exchanged between the associated magnetic and electric fields, but is not dissipated C. It is dissipated as kinetic energy in the circuit D. It … Read more

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 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

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

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