Radio works by transmitting and receiving electromagnetic waves. The radio signal is an electronic current moving back and forth very quickly. A transmitter radiates this field outward via an antenna; a receiver then picks up the field and translates it to the sounds heard through the radio.

There are three main components to most distributed antenna systems. These components include the Donor Antenna System, the Bi-Directional Amplifier, and the Distributed Antenna System. All three components work together to produce clear in-building communication signals.

A radio “system” is the brain or the infrastructure that makes improvements or indeed facilitates clear voice and data communication between two way radios. Many fully configurable functions can be incorporated into modern digital radio systems and these include, but are not limited to: Telephone Interconnect.

The prime purpose of radio is to convey information from one place to another through the intervening media (i.e., air, space, nonconducting materials) without wires. Besides being used for transmitting sound and television signals, radio is used for the transmission of data in coded form.

While radio has evolved over the years, from traditional AM/FM programming to digital alternatives such as Pandora or Spotify, listening to music and news is still a central and habitual part of daily American life. …

The difference is in how the carrier wave is modulated, or altered. With AM radio, the amplitude, or overall strength, of the signal is varied to incorporate the sound information. With FM, the frequency (the number of times each second that the current changes direction) of the carrier signal is varied.

FM uses a higher frequency range and a bigger bandwidth than AM. Each FM station is allocated 150 kHz of bandwidth, which is 15 times that of an AM station. This means that an FM station can transmit 15 times as much information as an AM station and explains why music sounds so much better on FM.

This isn’t the reason why AM sounds bad and FM sounds good. With AM radio, they’re allowed to carry by FCC regulations about 11Khz on each side of the AM carrier. So audio is decent, your car radio has narrow filters in it so you maybe only get about 5-6Khz audio bandwidth, making it sound muddy and low quality.

AM and FM modulated signals for radio. AM (Amplitude Modulation) and FM (Frequency Modulation) are types of modulation (coding). The electrical signal from program material, usually coming from a studio, is mixed with a carrier wave of a specific frequency, then broadcast.

In FM, the frequency derivation is proportional to the modulating voltage only. In PM, the frequency derivation is proportional to the modulating voltage as well as modulating frequency. Amplitude of FM wave is constant. Amplitude of PM wave is also constant.

FM is short for frequency modulation, which refers to the means of encoding the audio signal on the carrier frequency. FM full power, low power, translator and booster stations operate in the 88 – 108 MHz band. There are many classes of radio stations.

Nevertheless, AM radio has been in decline for years, with many AM stations going out of business each year. Now there are only 4,684 left as of the end of 2015. AM is dying for a lack of listeners. Only 10 to 20 % of all radio listeners listen to it, and that depends upon the locale.

The decline in AM audio was due more to regulation than to method of modulation. One aspect of radio not understood by most listeners is the concept of occupied bandwidth, or the amount of spectrum that a station uses to transmit its signal.

Most AM radio stations are required by the FCC’s rules to reduce their power or cease operating at night in order to avoid interference to other AM stations. However, during nighttime hours the AM signals can travel over hundreds of miles by reflection from the ionosphere, a phenomenon called “skywave” propagation.

When properly repaired and inspected, these old appliances are safe to operate, but if the condition is unknown, beware. Antique Radios may also contain hazardous substances, see Antique Radios and Asbestos.

Older radios tend to fetch somewhat more than newer ones, but only in a very general way. Age alone doesn’t make a radio priceless. 1920s radios are old, but some manufacturers made cheap, junky radios in those days, as in all other times. Scarcity of parts can make certain vintage sets very expensive to repair.

An antique radio is a radio receiving set that is collectible because of its age and rarity.

1920s radios were typically housed in wood, although some tabletops came in rather plain metal cabinets. Bakelite and Catalin were the most popular synthetic materials during the 1930s and 1940s. Other early plastics, such as Plaskon and Beetle, predated the flood of new synthetics that came along during the 1950s.

Today’s radio consists of an antenna, printed circuit board, resistors, capacitors, coils and transformers, transistors, integrated circuits, and a speaker. All of these parts are housed in a plastic case. An internal antenna consists of small-diameter insulated copper wire wound around a ferrite core.

In the mid 1890s, building on techniques physicists were using to study electromagnetic waves, Guglielmo Marconi developed the first apparatus for long distance radio communication. On 23 December 1900, the Canadian inventor Reginald A.

1967

Tubes, like analog recordings, have a more full-bodied sound than transistor gear. There’s a “roundness” to tube sound that solid-state gear never equals. Tubes are less forgiving about mismatches, so to get the best out of a tube amp it must be used with just the right speaker.

Shorthand for small radio dials. In the United States, the AM Broadcast Band (aka Mediumwave or Standard Broadcast Band) currently extends from 540-1700kHz. The “54” was simply because the radio didn’t start tuning the band at 500kHz nor 600kHz, but in between at 540kHz.

1990s-Today – Vacuum tubes are still used today. Musicians still use tube amplifiers and claim they produce a different and desirable sound compared to solid state amplifiers.

Blue Glow – We often get asked if blue glow inside of a vacuum tube is a sign of a defect. Thankfully, it is rarely a sign of a defect at all. It is most pronounced on power tubes and is the product of electron bombardment of the glass taking place within the tube.

All vacuum tube circuits operate at dangerous voltage levels. The 845SE and other powerful tube amplifiers operate at over 1000 volts. Accidental contact with an energized circuit of this nature would likely be instantly lethal.

Tube amps are expensive because they adopt pre and power tubes as their primary amplification source. Each tube costs roughly $50 and can have up to 4 of them within a single unit. Secondly, these amps have more expensive components, larger cases, and more complex circuitry than solid-state amps.

When a vacuum tube develops an air leak (a small crack or bad seal by a pin for example) this getter color will change to pure white. If you see this you know with 100% certainty that the tube is bad. Third, look for a purple glow that is very focused around specific elements inside the tube.

6 months

Tube amplifiers sound better because of the euphonic distortions they add to the music, as well as plenty of other reasons I’ll cover below. The ways that tubes distort when pushed to the edge are much more musical than the artificial sounds that come from transistor amplifiers when overdriven.