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FM Broadcast Translators and Boosters

By Ross Goodall WD4NJV

While listening to some broadcast stations you may hear a station ID followed by some additional call signs.  Examples in our area are WSOL and WAYR. 

Translator stations rebroadcast  the signal of a primary station on a different frequency whereas booster stations transmit on the same frequency as the main station. 1   

This works well due to the “capture effect” on FM in which a receiver captures the strongest signal and rejects the weaker signal. 

Translator call signs in the United States begin with W or K followed by the channel number and a two-letter suffix.  Booster stations use the call sign of the main station followed by FM and the booster number.

Commercial Booster stations usually receive the main stations signal off the air, but may use microwave, phone, internet and optical fiber but not satellite.  Non- commercial booster stations may also use satellite.

Translators may be fill in or non-fill in.  White area refers to areas outside the area of the coverage area of any AM or FM station. 1 

FM translators may be used for cross band coverage.  Station ID’s must be given three times a day and maximum output power is limited to 250 watts. These stations are referred to as rebroadcasters in Canada, complementary stations in Mexico. 2

In densely populated areas with such as Tampa, St Petersburg and the Suncoast area there are many examples of translators and booster stations being used. For a detailed discussion of the rules refer to FCC webpage.

References:

1 FCC.gov, FM Translators and Boosters

2 Wikipedia, Broadcast Relay Station 

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WSM AM 650 kHz Tour and History
By Ross Goodall, WD4NJV

On a recent visit to Nashville TN, I had the pleasure of visiting the studio of WSM. 

WSM is a full time 50 KW FCC authorized clear channel station that is easily heard at night in Jacksonville. The daytime coverage map is impressive.  1   

For those of us that have not toured a commercial station in many years, the changes are numerous as computers and technology have come into play.  The console consists of just computers and computer monitors. 

All music, advertising (known as traffic) as well as IDs are on computers.  Gone are the days of turntables, cart machines, reel-to- reel tapes, written log books.  Also gone are the days of being invited in to sit and talk with the announcer.

The studio has a main desk with professional boom mikes and settings for three additional persons to go on air facing the announcer.

Transmitters now are more trouble free and frequency measurements are not required to be taken as often and someone does not have to be present to watch the transmitter.  If the station is out of compliance with FCC rules, the station owner is held responsible not the chief engineer.

WSM History

Station sign on was in 1925.  WSM was known for the popularization of country music and especially the Grand Ole Opry.  In 1932, power was increased to 50 KW.

After the popularization of television, soap operas and other full length radio shows decreased.  More middle-of-the-road music was played in the daytime with country music at night. 

WSM played a big part in Nashville becoming the recording capitol of the United States.  Performers wanted to be heard on WSM to launch their careers and sell their music. 

Nashville became known as Music City USA. The call sign WSM stands for “We Shield Millions” which is a fitting call for its original founder and owner, National Life and Accident Insurance Company.

WSM gave brand recognition to the insurance company.  Famous personalities of WSM include Ralph Emery and Pat Sajak and Larry Gatlin.   2,3

Tower

The tower was originally 878 ft. tall and was the tallest in North America.  Later the tower height was reduced to 810 ft. because it did not resonate properly.  (AM broadcasters usually energize the entire tower)

The tower sits on a single insulator on its base. 2,3

There are several interesting YouTube videos of the tower.  4
 
References:
1              Radio locator.com WSM 650 AM
2              WSM (AM) Wikipedia
3              Nashville Broadcasting History, WSM
4              YouTube WSM 

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AM RADIO EXPANDED BROADCAST BAND

By Ross Goodall, WD4NJV

Most modern AM broadcast radios will tune up to 1705 kHz.  Many years ago, above 1600 kHz. was a police radio band. Older radio dial markings may show this as police band. 

In the 1990s, the FCC approved commercial broadcasters to use this band with a preference to AM stereo applications.  AM stereo never caught on. 

Normal FCC standards allow output powers of 10 KW daytime and 1 KW nighttime omni-directional in this band.  An exception is a Brownsville, Texas station that runs 12% less power to satisfy a treaty with Mexico. 

Mexico has four licensed expanded band stations that operate with nighttime power greater than 1 kW which were authorized before rule changes in 2014.

Normal channel spacing for the United States and Mexico is 10 kHz and 9 kHz in other areas. 1

Reference:
1. Wikipedia:  AM Expanded Band 

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