Amateur Extra: Toxic Materials

Toxic Materials

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

Amateur Extra: Estimating RF Fields

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

Amateur Extra: ASCII Parity Bit

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

Amateur Extra: JT-65 Encoding

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