kb8tq@n1k.org said: > All of those motors in the building are rotating at line frequency. You > don’t just have an electromagnetic field. You can have an acoustic / > vibration field as well. Probably not a big deal, but it’s there …. Most of the medium sized motors run at slightly below line rate, and often at half of line rate. I'm thinking of the classic squirrel cage induction motor vs a synchronous motor. A quick google search found 1725 and 1750 RPM. Is it possible to measure things accurately enough to notice that? -- These are my opinions. I hate spam.

Hi ummm …… errr ….. yes. If you mount the OCXO that drives an 800 MHz FM narrowband transmitter in the middle of a wall panel on the rack, you *can* measure the rotation speed of the blowers. That’s not a guess, that’s empirical knowledge :) Bob > On Jul 12, 2016, at 8:24 PM, Hal Murray <hmurray@megapathdsl.net> wrote: > > > kb8tq@n1k.org said: >> All of those motors in the building are rotating at line frequency. You >> don’t just have an electromagnetic field. You can have an acoustic / >> vibration field as well. Probably not a big deal, but it’s there …. > > Most of the medium sized motors run at slightly below line rate, and often at > half of line rate. I'm thinking of the classic squirrel cage induction motor > vs a synchronous motor. A quick google search found 1725 and 1750 RPM. > > Is it possible to measure things accurately enough to notice that? > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

Just to clarify - AC motors are either synchronous or induction. Induction motors must slip away from line frequency to develop the magnetic field they need to carry a load. The name plate speed is for rated load and the number of magnetic poles in the rotor. A 2 pole motor spins near line frequency - 4 poles at half. 1750 is for a 4 pole motor. And so on ... Bill Hawkins -----Original Message----- From: Hal Murray Sent: Tuesday, July 12, 2016 7:24 PM Most of the medium sized motors run at slightly below line rate, and often at half of line rate. I'm thinking of the classic squirrel cage induction motor vs a synchronous motor. A quick google search found 1725 and 1750 RPM.