[Boatanchors] decibels (was Microphone Output)

[rbethman]

Eugene has hit it squarely on the head.

I went through all this attempt to "define" dBm when I obtained an HP-3336B.

All of its output settings are done using dBm.

I finally found a darn good table out of Germany.  It gave me the 
voltages in P-P, RMS and whatever.

</http://ifmaxp1.ifm.uni-hamburg.de/DBM.shtml>


/I needed to determine this since this is going to be used as a VFO for 
a BC-610

Bob - N0DGN
On 1/11/2013 12:04 PM, W2HX wrote:
> Just a minor correction:
> dBm = power relative to 1 mW dissipated (this is impedance independent, not 600 ohm).
>
>
>   
> 73 Eugene W2HX
>   
>
> -----Original Message-----
> From: boatanchors-bounces at mailman.qth.net [mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of David Stinson
> Sent: Friday, January 11, 2013 11:40 AM
> To: boatanchors at mailman.qth.net
> Subject: Re: [Boatanchors] decibels (was Microphone Output)
>
> "dB" is the unit of measure of a relative logarithmic ratio, usually involving power or amplitude.
> It needs a suffix to define a point of reference to which the reading is relative.
>
> A few examples of these units are:
> dBm = power relative to 1 mW dissipated in 600 ohms.
> dBW = power relative to 1 W regardless of load impedance.
> dBi =  gain of an antenna relative to an isotropic radiator.
> dBd = gain of an antenna relative to a dipole in free space.
> dBV =  voltage relative to 1 volt, regardless of impedance.
>
> A chart of the ratios and more info than you want is at:
> http://en.wikipedia.org/wiki/Decibel
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