RailRoadFan.com

For our school's senior parade, I got the green light from the school staff to use my buddy's train horn, it's a 1st generation Nathan K5LLA with a 1L bell. I was using a craftsman 6-gallon air compressor if that means anything.

I tried blowing the horn to a horn sequence, and on the second blast, the 1L chime started playing a D-sharp when I blasted it (it's supposed to play a C). After the parade I took it to my buddy's place, he blew it on his truck and air hose and it worked perfectly fine, he really didn't give me a good explanation as to why it did that. I'm not sure if we have any horn geeks on here, but does anyone know what the reason might've been? The air compressor? The air hose I was using?

I'm no expert but logic would dictate that if the horn is blowing a lower note than it should then that means there's not enough air pressure.

A horn not sounding properly is either:

-Damaged
-Dirty/Clogged
-Not getting enough air. For locomotive horns to sound properly, they need 90-120 psi, and at least 1/2 ID air line. You also need to make sure the horn is getting enough CFM. That little 6 gallon compressor will never make enough air to blow a K5LLA properly for more than a few seconds at most.

Definitely not enough air pressure, because of tank capacity. A 6 gallon tank will not get you far with a 5 chime. Especially if your pressure started at around 120psi.