Thunderbolt 1000T

Intro The Thunderbolt is a line of supercharged rotating sirens formerly manufactured by Federal Signal. At the time of its release, it sported nearly unrivaled sound output and continued to be a popular siren even as newer sirens surpassed it until its discontinuation 38 years later. The Thunderbolt is perhaps the most well-known of all North American civil defense sirens, even with those who are unfamiliar with sirens. It was sold alongside the naturally aspirated Model 500 rotational sirens. it's chopper can be 4/5 or 5/6. Development of the Thunderbolt began as early as 1951. While originally envisioned with an angled down horn and a rounded rotator and blower housing, the design would be refined by 1952 with rectangular housings replacing both to simplify construction. The Series A1 Thunderbolt Type 1000 was released in 1952, sporting several differences from later models. Most units constructed between 1952 and 1954 had three grids of steel reinforcements in the horn as Federal was unsure of whether or not the horn was at risk of warping. As units began to be produced without these reinforcements, it was found the horn was strong enough without them. Mesh screens were added to the horn keep out debris as early as 1953. These early reinforced units are often called "jailbar" or "gridface" units by most enthusiasts. Later Series A1 units had slightly taller rotator enclosures. In 1954, the dual tone Thunderbolt 1000T was introduced. The 1000T originally used the 4/5-port dual tone rotor from a Model 2T; by 1959 5/6-port dual tone became the standard, and 4/5-port was exclusive. The Type 1000T became the standard model of Thunderbolt upon introduction, though the Type 1000 was still available as an option. Due to the Office of Civil Defense's requirements for air raid sirens to be dual tone, the Type 1000T was intended for civil defense purposes, while the Type 1000 was offered for other applications, though it could still be used.