When I lived in Hawaii, a friend encouraged me to become an amateur ham radio operator by obtaining a general operator's license. To do this I needed to pass a written exam on the theory and circuitry of radios and pass a Morse code test which involved sending and receiving eleven words per minute. I passed the written test on the first try, but it took three trials for me to pass the code test. Radio transmission and reception depends on the transmitting and detection of electromagnetic waves, and to do this the antenna and circuitry must be accurately tuned to certain frequencies and wave lengths. For example, amateur radio has been assigned five frequency bands, six meters, 15 meters, 20-40 meters, 60 meters and 75-80 meters. These numbers refer to the wave lengths involved. Since a meter is approximately three feet, this means that in order to receive these transmissions the antennae must have lengths ranging from 18 feet to 240 feet. I happen to have a two-story house, so a wire in the shape of an inverted "V" stretched from one corner of my lot to the opposite one is just long enough to receive 80 meter waves. Some antennae such as beam and vertical antennae can be much shorter by using coils to compensate.
However, not only do antennae need to be tuned, but also the circuitry must be finely tuned. When we turn a knob on the radio or punch a button on the TV remote, we alter the capacitance of the circuitry so that only certain frequencies are resonated and amplified and all other frequencies are eliminated. This tuning is very precise and closely regulated by the government so that there is no interference between radio and TV stations in a certain area. Some times this fine tuning is interrupted or garbled by some natural electrical or magnetic cause such as sunspots or lightning. Older shortwave radios had a tendency to wander off frequency as the old tubes warmed up, but modern solid state sets with transistors and digital tuning have eliminated the problem. Just a very small change on the dial can mean the difference between a good signal and a poor one.
We are constantly being bombarded with electromagnetic radiations such as AM/FM radio, TV, high frequency HF, very high frequency VHF, ultra high frequency UHF, cosmic rays, X-rays, gamma rays, and microwaves which we cannot detect without equipment that is designed to receive them. Similarly, we are the recipients of a multitude of divine messages that we can receive only if we are tuned in. These messages may be from God's word, from preachers of God's word, from nature, from the voice of conscience, and sometimes a still small voice that says, "This is the way, walk ye in it." The messages are spiritual in nature, and therefore must be spiritually discerned. They are messages of counsel, love, and salvation. How important it is that we are spiritually receptive to these divine transmissions, that we are spiritually "fine tuned."
