News TWR Bonaire Radio Station Featured in World Radio TV Handbook 2019

January 2nd, 2019

TWR Bonaire Radio Station Featured in World Radio TV Handbook 2019

Complexities of Installing a 450 kW Transmitter

Last year TWR-Bonaire's Broadcast Engineer Dave Pedersen was asked to write an article about the reasons for and the operational complexities, installing a new MW transmitter at TWR's Bonaire radio station.
This article below is published in the 2019 edition of the World Radio TV Handbook. This book is published annually as a reference of broadcasting stations worldwide and used by both professionals and hobbyists. It is primarily written for a technical audience.

The voice of hope across the Caribbean and South America got a lot louder in January 2018 as TWR inaugurated the most powerful radio station in the Western Hemisphere. Known as ‘Shine 800AM’, the station broadcasts Bible-based Gospel programs on 800kHz from its new 440kW transmitter. The station has a potential audience of more than 100 million listeners from Cuba south to Venezuela and Brazil, as well as from the Yucatan Peninsula east across the Caribbean. TWR president Lauren Libby describes the station as “a big voice for Jesus”.

TWR began broadcasting from Bonaire in 1964. Initial broadcasts were on medium wave to the Caribbean and South America and on shortwave to many other regions of the world, supplementing TWR’s other transmission facility at the time in Monaco. The shortwave transmissions from Bonaire ceased in 1999 as TWR broadcasting facilities grew around the world, with regional studios and transmitters serving their regions more directly.

TWR now broadcasts over a global network of transmitters owned by TWR as well as facilities owned by many partners worldwide. Since its inception in 1952, TWR has grown to become one of the world’s largest multinational Christian media outlets. Its radio transmissions now speak hope to the world in more than 230 languages and 160 countries. Known for several decades as Trans World Radio, the ministry’s branding identity was changed to TWR in 2009 to reflect the organization’s growing use of other communications media. TWR has, however, also continued to increase its radio ministry. TWR Bonaire began medium wave broadcasts in 1964 with 500kW, operating a variety of tube-based transmitters until 1999. The facility initially operated its own power generators because the power demand was more than the local infrastructure could provide. The island’s power grid and generation capacity have expanded, and adequate power is now provided commercially.

Return to High Power is Needed
Unfortunately though, the high cost of electricity on the island led to a reduction of transmitter power to 100kW in 1999. Since then many listeners have reported they could hear the signals from Bonaire only poorly or not at all, a situation made worse by the increasing noise floor in urban areas. It became clear by the end of 2010 that a return to high power was needed. Because the station retained its 500kW licensing, TWR was able to start the Bonaire ‘Power Up’ project in 2011, bringing back superpower broadcasting to the Caribbean with the 2018 inauguration of a new Nautel NX400 transmitter. This was chosen for its cost, reliability, and high efficiency: it typically operates at greater than 92 percent total efficiency and is an entirely solid-state transmitter. TWR Bonaire also uses modulation dependent carrier level control (MDCL) that reduces carrier power on modulation peaks, lowering electrical costs by another 30 per cent.

Installing and Operating New Transmitter
After visiting the Nautel factory in Canada for training on installing and operating the new transmitter, TWR staff members performed the transmitter installation themselves. A broadcast station is a system, much more than the transmitter alone. More RF output power requires more of everything else. New electrical transformers were installed by the local power company. The hall that housed the old 500kW tube in the 1990s needed renovation; one quarter of the hall is now dedicated to the Nautel NX400 and the rest houses the new phasor array from Kintronic Labs. New 30-ton air-conditioners were installed to cool the transmitter and hall, new feedlines had to be run, and the four-tower array was modified to handle the higher power. The layout of the antenna array is rectangular, with two towers being driven and the other two acting as reflectors when beaming northwest towards Cuba or southeast towards Venezuela and Brazil. A single tower is employed for the modified nondirectional Caribbean pattern. The southern part of the island of Bonaire, where the TWR transmitter is located, is very lowlying. The radial system is less than 60 centimeters above the limestone layer that is permeated with ocean water, and very close to the seashore and salt ponds. The ground conductivity in this layer is extremely good, further enhancing the antenna effectiveness and lowering the radiation pattern. The negative side of this location is that the salt-laden trade winds lead to a continuing battle with corrosion. The towers must be scraped and cleaned every two years.

Hundreds of People used Vacation Times to be Part of the Project
Most of the installation work was performed by dedicated volunteers assisting TWR staff over the course of a five-year period. They helped with building renovation; electrical system and air-conditioner installation; construction of the new antenna tuning unit houses (which have no nails or screws in the roofs to avoid the risk of corona discharge starting a fire in the high-RF field); painting; and phasor and ATU assembly. Hundreds of people used their vacation times to be part of the project. The entire power upgrade was funded by donations, with work proceeding as funding was received. In addition to daily broadcasts of inspirational gospel messages, Shine 800AM serves the Caribbean during and after natural disasters. Its high power transmissions can effectively reach any island or country in the region. Ground wave signals travel very well over the ocean even in broad daylight. The station broadcast special programing during and after hurricanes Irma and Maria in 2017, as well as after the Haiti earthquake in 2010. Bonaire is located south of the hurricane belt and is therefore usually unaffected by the passing storms, so the station is in a good position to assist others.

Broadcast Schedule
Shine 800AM broadcasts overnight on 800kHz from 2130 to 1230UTC. The direction and power of the broadcasts change throughout the broadcasting period based on distances and propagation to the intended audiences. The current broadcast schedule can be downloaded here. More information on TWR’s work worldwide is available at www.twr.org.

Reprinted with permission from the World Radio TV Handbook, 2019 edition. http://www.wrth.com/