This picture shows the large building that was located on Transmitter Road just east of Lacombe. The state police helicopter was hovering overhead because the photo was taken during a hostage/active shooter exercise conducted by the state police back in the 1970's.
In the 1950's and '60's St. Tammany Parish was home to two large transmitter operations for radio communications, one just east of Lacombe and the other in the the Slidell area.
According to folks on the Slidell history Facebook page, the one in Slidell, originally off of East Gause Blvd., was owned by Tropical Radio Transmissions (affiliated with Standard Fruit And Steamship) and moved to Pearl River in the 1980's. The Pearl River station was where the radio operators sent/received messages to ships via morse code. They also had telegraph service to Central and South America. Tropical Radio was started so United Fruit could keep track of their banana plantations and the ships carrying the bananas. The Slidell station was the Antenna field.
The one out by Lacombe was the transmitter site for the FAA out of New Orleans or involved ship-to-shore communications, some commenters believed.