[Amps] conversion scale from dbu to microvolts

[Peter Chadwick]

Jim said:
>In the case of the field strength usage of "dBu" (0 dBu = 1uV/m), the 
behavior of the receiving antenna is part of the relationship between 
that field strength and the power and voltage at the receiver input. 
That makes any use of this field strength dBu to describe receiver 
performance completely non-sensical. <
Precisely. You can only define a receiver performance in field strength when it has a buit in antenna, and then, only under very specific conditions.
It's normally considered that the measurement uncertainty on a radiated measurement is +/-6dB, although you will do better in a good anechoic chamber - maybe +/-3dB.
Some of this may be a degree of sloppiness, using 'dBu' where 'dBuV' is intended, the 'u' being really a Greek letter 'mu'. I haven't seen 'dBu' used over here to mean 'dBuV/m', though.
I suppose you could specify the gain of a receiving system in dBuV/m if you specified the Antenna Factor, which is the number relating microvlts/meter to volts at the receiver input. I believe they do that effectively for noise emasurement, using a standard 9 foot long whip.
Also, look at the uses of 'mu'. In radio, as a shortened 'micro', or as the 'gain' of a vacuum tube. Then it's also used for refractive index and coefficient of friction. No wonder there's confusion between disciplines at times!
73
Peter G3RZP