Federal Sirens
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Here are some miscellaneous Federal siren photos I have taken over the years and a few from other sources.

Federal Signal Model 2

The Federal Model 2 is a small siren that Federal states produces 102db and 100ft. It is a single phase 2hp siren and is single tone. Federal also made dual tone Model 2T. The Model 2 single tone siren has 5 ports and the dual tone Model 2T has 4/5 ports. Federal states in their old Model 2T manual that the Model 2T had and output of 100db and 100ft.

Federal Signal STH-10

Here's a close-up photo of a STH-10 at the Richardson fire training facility. This siren was almost in new condition when this photo was taken and I don't believe was ever installed. It was sold at auction in 2008.
The STH-10 model siren has 12 ports, is single tone with a 7-1/2hp motor. That's the motor on the top of the siren in the picture. The large tube on the bottom where the stand legs attach is the air intake tube for the siren. The Federal STH-10 manual states the sound output as 115db at 100ft and a top sound frequency of 694hz.

Federal 2T22 Allen, Texas

I think the Federal 2T22 is probably the nicest sounding of all the dual-tone Civil Defense sirens. The 2T22 is essentially 2 sirens using one motor. The upper part of the siren has 12 ports and the lower has 10 ports resulting in 2 tones produced and it is driven by a 10hp motor. The motor is in between the two siren rotors. The air intake for the upper siren rotor is just under that little hat on the very top of the siren. The air intake for the lower siren rotor is (like the STH-10 above) through the tube between the siren mounting legs at the bottom of the siren. Actually when the City of Allen put this siren up it was mounted to the pole incorrectly. The pole extends up into the lower rotor air intake which must have blocked a large volume of the incoming air. The tone frequency is 675hz high and 575hz low tone. I'm not sure what the production span of this siren was. I'm guessing it came out in the 1960s some time and then Federal stopped production in the late 1980s or early 1990s? There is also another version of this siren, the 3T22 which is capable of producing the fire signal. See a detailed explanation of the 3T22 here.

Federal SD-10 Siren

The Federal SD-10 is a dual tone siren with a 7-1/2HP motor. It's similar to the STH-10 and STL-10 in that the motor is on the top and the air intake is on the bottom. Obviously the housing on the SD-10 is the most unusual thing about it. Evidently since the SD-10 is dual tone and individual projector horns wouldn't line up with two separate rows of different number siren ports Federal went with this unique housing. The whole housing is like a projector horn. The siren had one row of 12 ports and one row of 9 ports resulting in a 4/3 port ratio. The Federal manual states that the SD-10 has a high tone frequency of 694hz and 521hz low tone and the sound output is 109dB and 100ft.

1952 Federal Thunderbolt Siren Photos

I recently found some fantastic photos on the Seattle Washington Municipal Archives web site. They have a large number of vintage photos in their archives. Among these photos are these 2 of a mobile Thunderbolt siren mounted in the bed of a Ford pick-up truck. These photos are dated February 1952 so this must be one of the first Thunderbolt sirens. Notice in the photo of the front of the truck that the RCM control cabinet can be seen behind the truck. It looks to me like they were testing their new Thunderbolt with a temporary hook up. I can't figure from these photos where or how this siren would have been used. The horn is mounted so low above the cab I think that the vehicle would have to have been driven to a location with a high elevation and hooked up to remote power to operate it. I don't know. Maybe this is a demonstration vehicle that came from Federal to demonstrate the siren. Well I don't know about that either. I just noticed that the truck has a Washington license tag on the front. Maybe the Federal sales rep. was in Washington. Who knows... Just another unanswerable question lost in the forgotten history of civil defense. I emailed the archives and they were kind enough to take the time to scan the negatives for some high resolution photos.

I received an e-mail from Larry Price from Seattle in Feb 2005 concerning this photo. Here are Mr.Price's comments.....

"Mr. Green:

I recently came across your website by accident, and spotted the two Seattle pictures of the siren mounted on the Ford pickup truck. I am an employee of the City of Seattle, and can (if nothing else) give you the exact location that the pictures were taken at. The site is the East side of the Southern approach to the Freemont Drawbridge. It is now and has been for many years the location of our Drawbridge Operations and Maintenance Shop. This bridge is one of several drawbridges across the Ship Canal that bisects the city from East to West. From the license plate, I strongly suspect that this truck belonged to the City. I can't imagine a more unlikely place to test a siren, unless they wanted to minimize it's sound impact on the surrounding area. There is a very steep and high bluff located not far behind where the photographer would have been standing. An earth embankment as well as the concrete bridge structure are blocking sound to the West. Some of the buildings seen in the background still exist."

Click on each photo to see larger.
I have a photo of the RCM cabinet above on my Thunderbolt Information Page.

Fort Worth Whelen and ThunderboltI would like to thank the Assistant Emergency Management Director of Fort Worth Texas for sending this photo. Fort Worth's new siren system is installed and the old sirens were taken down in 2007.