November 15, 2013

FCC Technician Exam Question Of The Day (T1B09)

Q) Why should you not set your transmit frequency to be exactly at the edge of an amateur band or sub-band?

A) All the following are correct.
- To allow for calibration error in the transmitter frequency display.
- So that modulation sidebands do not extend beyond the band edge
- To allow for transmitter frequency drift

Note from NJ2X: You definitely do not want to transmit outside the amateur radio bands since it is illegal.  However, this is exactly what will happen if you are transmitting on a frequency that is at the very edge of one of the amateur radio bands.  That is because all modes of communication use a certain amount of bandwidth so your radio is transmitting over a frequency range and not just the frequency you are tuned to.

For example, when transmitting on upper side band on 28.500Mhz the frequency range would extend up to 28.500Mhz + 3Khz.  Technician privileges end at 28.500Mhz so any voice transmission above this frequency would be illegal if made by a technician license holder.