Here's a diagram I found of how a diaphragm horn works: (You may have to zoom into the diagram, it is kind of small) https://upload.wikimedia.org/wikipedia/commons/thumb/f/f8/Powerchamber.JPG/220px-Powerchamber.JPG It doesn't show this in the diagram, but the air pipe going into the horn connects to...

Sorry for another bump, but I have some info about the mystery siren: - It has a small handle on the top, possibly to be lifted by a crane? (I'm not sure about why it has one) - The choppers are actually attached to a gearbox. The motor itself is actually the base (the middle section of the siren is...

I found one more in Michigan: 2001-DC "Roundback" - 43°10'30"N 83°16'39"W (CD yellow, no street view)

Here are some locations for Michigan: (you may have to look around the coords in satellite view to find them, it rounds coords to the closest building/park) Portland: 2001-DC "roundback" - 42°51'53"N 84°53'29"W 2001-DC "roundback" - 42°52'16"N 84°54'38"W Blue ...

If anyone wants to help with this map here it is! https://www.google.com/maps/d/edit?mid=1g9OgYZBrMkJ-3kKygYrgjf4wVEpS6yk&ll=34.891644730509526%2C-93.67729247527114&z=7 When I try to open the map, a message saying "you need access" shows up. Have you made the map public yet? You n...

Sorry for the bump, but Amarillo, and PANTEX testes their sirens on the Last Friday of the month at 11:30 AM. (weather permitting) Canyon, TX testes their sirens on the Last Friday of the month at 12:00 Noon, weather permitting. Fixed! You didn't bump that much. I was actually hoping for edits to t...

To me, it almost looks like a Model Q without its chrome bits and motor cover. I could be wrong. That's what it is. A Q2B without a chrome cover and without a motor. Of all things, why a Model Q2B? I'm guessing now that they didn't have the budget for a Model A or another small siren, so they proba...

Heath was very successful in California, there are far more than just 2 sirens built by the company. The Heaths you're seeing are mostly the Type K, which doesn't really have a specific design and each Type K looks slightly different from one another. There's an article on the CDS Wiki about Heath ...

I was looking around the California siren map, when I noticed that there was a Heath siren on top of the Kenwood FIre Protection District, and it even does noon blasts! I started looking around more, and there was actually 4 more that I didn't even know about, all active and one inactive (according ...

I'm not sure if there is any in Georgia or around it close enough to it. If there is one, I haven't heard of any or it could be small enough to not get talked about. The closest graveyard I can think of is West Shore Services (WSS) in Michigan, but that is a long way away. If you were looking to buy...