The 500-DHTT (sometimes misnamed as the 550-AT) was introduced in 1953 alongside the other models, and was a dual rotor, dual horned rotational siren. The 500-DHTT made use of the rotors from both the 8-port and the 12-port variants of the Federal C3 1/2 Model 7, with one on each side combined made the siren 8/12 port dual tone.

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© Sam Nudge 2019 do not reuse content from this video. it's been roughly 7 years since I've done one of these videos, so now I'm here with the best video on YouTube of the Calhan Federal Signal...

May 6th, 2022 The Federal Sign and Signal 500DH-TT in Calhan, CO activating for its annual test. This year they tested on their normal date (first Friday in May) but at 10am. They didn't do the...

2016年3月27日 · Rochester, IN reportedly had a 500-SHTT located on Madison Street - this one was located in a parking lot, however a brief Google Maps search suggests this siren is also gone. Madison, WI used to have 3 500Ts across the city. These 3 phase 240 volt sirens were installed in 1976. They were located on Charleen Lane, Ferris Avenue, and Hammersley ...

2009年11月14日 · Federal Sign & Signal Corp. 500-DHTT Horizontal axis, bidirectional, 670 & 450 cps DHTT would presumably be Dual-Head (DH), Dual-Tone (TT). The listed frequencies work out to essentially a 12/8 port siren, which is what the Calhan, CO siren sounds like.

The 500 was a Siren by Federal Sign and Signal (Now Federal Signal) and is Very Rare... Due to its Rarity Only few pictures and Videos exist online about this siren.. The 500SH-TT, 500DH-TT, 500SH, and 500AT also exist.

2009年6月1日 · What a Federal Signal 500-DHTT sounds like from 700 to approx 1,000 feet away.

2020年7月27日 · Here's a 1967 500-DHTT from Reno, NV. Reno purchased 4 of them. 1967.JPG. I didn't know they were still making 500-DHTTs in 1967. I was under the impression that they were discontinued in the 50's. Also, I might be wrong, but I wonder if the 500-DHTTs that some fire departments in Nevada have now came from Reno.

2024年11月4日 · The 500-DHTT (sometimes misnamed as the 550-AT) was introduced in 1953 alongside the other models, and was a dual rotor, dual horned rotational siren. The 500-DHTT made use of the rotors from both the 8-port and the 12-port variants of the Federal C3 1/2 Model 7, with one on each side combined made the siren 8/12 port dual tone.