[TenTec] RE: dBm

[AC5E at aol.com]

Unless they have changed the definitition since they changed cycles per 
second to Hertz; a dBm is  "decibels referenced to one milliwatt at a specified 
impedance."  Back in those days, unless some other impedance was specified a dBm 
was taken to be 1 milliwatt into 600 ohms for professional audio work. 

+ 67 dB is 2,000,000 times  ( as close as I can read the scale on this 
slipstick, or so close not to matter)  the 0 dB level,  and - 67 dB would be one 2 
millionth of the 0 dB level of 1 milliwatt at the specified impedance. If you 
don't have a calibrated milliwatt meter, that's about 5 millivolts on an AC 
voltmeter or 5 mv p-p on a calibrated o-scope. 

73  Pete Allen  AC5E