Direct Observation

Propagation conditions can be determined directly by listening to the HF band. The simplest method is to tune higher in frequency until no more long-distance stations are heard. This point is roughly just above the MUF to anywhere in the world at that moment. The highest usable amateur band would be the next lowest one. If HF stations seem to disappear around 23 MHz, for example, the 15-m band at 21 MHz might make a good choice for DXing. By carefully noting station locations as

well, the MUF in various directions can also be determined quickly.

The shortwave broadcast bands (see Table 21.5) are most convenient for MUF browsing, because there are many high-powered stations on regular schedules. Take care to ensure that programming is actually transmitted from the originating country. A Radio Moscow or BBC program, for example, may be relayed to a transmitter outside Russia or England for retransmission. An excellent guide to shortwave broadcast stations is the World Radio TV Handbook, available through the ARRL.