The Siren Board

I have recently found some time to spend on my B&M 20-AR-7 air raid siren, Tonight, I counted the ports on each side and came up with 16 on one side and 20 on the other, anyone know if this is the common configuration for a two-tone siren?
Air Raid

Well then...this is the first time I've ever heard of a 16-20 port siren! Decot did make a 15-20 port, but that was the closest to this. Are there any photos?

Thanks for the reply, unless I somehow counted these wrong, that's what I came up with, just make sure I counted each side multiple times...same answer. I assume that the ratio would remain the same if a smaller siren had a 10 to 8 ratio...or is that wrong? This a large siren, each section is eight inches wide.

Air Raid

Should have a photo in a week or so. I am remounting the covers that were removed when this siren was removed from atop the county Sheriffs Office building. I am going to try and attach a photo that is somewhat similar to mine, other than the cover is one piece and the sections look similar where mine has obvious differences where one side has 20 ports and the other side has 16 ports.
https://thesirenboard.com/forums/downlo ... ew&id=5875

Could it possibly be a unit simmilar to this mystery posted 8 years ago?

The image I sent you looks similar to your mystery siren.The image I sent to you I found on line and am unsure who made it, I only sent it to you as an example of a large horizontal siren. I talked this morning to the owner of B&M siren in LA and he claims that he only knows of three others like mine and even at that two apparently are seen at a distance so he is not sure if the same as mine or not. B&M, according to the owner did not make many large horizontal sirens. The largest one they made was the model 20-AR-10, which was a 10 HP 3 ~ siren that was 20" in diameter and 10" wide.
The next largest one they made and the one that I have is a model 20-AR-7 and uses a 7 1/2 HP 3~ motor. It is also 20" in diameter and is 8" wide. The application rating chart shows mine is made for "Large Cities". I know that the one I have can be heard at least three miles away. I have the original CD control unit and other misc. electrical and control pieces as removed from the Sheriff's Office-

Post some good images-this sounds Rare!

Here is an original ad for one

Air Raid wrote: ↑

Tue Dec 05, 2017 2:50 am

I have recently found some time to spend on my B&M 20-AR-7 air raid siren, Tonight, I counted the ports on each side and came up with 16 on one side and 20 on the other, anyone know if this is the common configuration for a two-tone siren?
Air Raid

16/20? Wow! At 1725 RPM, it would sound sort of like an 8/10 port 3450 RPM siren (ACA hurricane) Can you check to see what the motor RPM is, and if possible, post pictures?

estokke09 wrote: ↑

Tue Dec 05, 2017 11:29 pm

Here is an original ad for one

I really want to see a 6-AR-1 now... never heard of an outdoor warning siren that small. Smallest siren I know of was the Fedelcode model 1.