Radio Shack DX-398 Owner's Manual

41BIRDIESBirdies are the products of internally generated signals that make some frequenciesdifficult or impossible to receive. If you program a birdie frequency, you hear onlynoise on that frequency. The most common birdies to watch for on this receiver are:Notes:• See “Storing SW Frequencies in Memory” on Page 28 for more informationabout using the shortwave page 29.• Interference from devices such as dimmer switches and motors and atmo-spheric conditions can disrupt shortwave listening. You can minimize interfer-ence by moving the receiver away from the source of noise, or turning off theoffending device. Shortwave stations sometimes change their operating fre-quency to avoid interfering with other stations, to improve reception during dif-ferent seasons, or to take advantage of signal propagation changes due to sunspots. For this reason, a given station might not be found on the frequencylisted in memory. Reception of these stations can also be affected by rapidchanges in the ionosphere. Sometimes the station you are listening to mightfade out completely. These occurrences are normal shortwave listening condi-tions.AMATEUR SHORTWAVE BANDS IN THE USAmateur radio operators in the U.S.A. are found in the bands listed here. They op-erate mostly in LSB (Lower Side Band) mode. Morse code operators are generallyfound in the lower areas of each band. The amateur radio operators with the mostadvanced classification are found in the upper areas of each band.450 kHz 3,844 kHz 9,000 kHz 10,250 kHz18,000 kHz 20,490 kHz 21,835 kHz 21,868 kHz