## Re: [softrock40] Power and Signal Levels

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• BTW, the decibels difference between the two signals should be 20*log(50uV/1uV) or 10*log(2500/1) both of which are 34 dB, not 17dB. Bill wa9pwr
Message 1 of 8 , Apr 29, 2007
BTW, the decibels difference between the two signals should be
20*log(50uV/1uV) or 10*log(2500/1) both of which are 34 dB, not 17dB.

Bill wa9pwr

Kees & Sandy wrote:
>
> Interesting ....I've always connected a pad or termination across my
> signal generators (URM-25 or HP-8640) to get the levels correct
> relative to the meters since most are designed and set up for a 50ohm
> load. I assumed the XG-1 or XG-2 would be the same. I think we need
> some more input.
>
> 73 Kees K5BCQ
>
>
> -- Bill Dumke <billd@...> wrote:
> No pad. Direct connection. The XG1 was used to calibrate Rocky 3.2's
> S-meter.
>
> Bill wa9pwr
>
> Kees & Sandy wrote:
> >
> > Is that with a 50 ohm pad in there somewhere ?
> >
> > 73 Kees K5BCQ
> >
> >
> >
> > -- Bill Dumke <billd@...> wrote:
> > Kees,
> >
> > I get 26 dB difference here using my XG1 and Rocky 3.2. It goes from
> > -68 dB to -42 dB from 1 uV to 50 uV.
> >
> > Bill wa9pwr
> >
> > Kees & Sandy wrote:
> > >
> > > I thought I knew this ....but, so I'll ask.
> > >
> > > S-meter readings are really a measurement of the power in the passband
> > > where the AGC and S-meter circuits are and assume a properly
> > > terminated antenna input, usually 50 ohms. The "standard" is S9 which
> > > equates to 50uV at th e 50 ohm impedance antenna terminals and can also
> > > be stated as -73dBm from a voltage standpoint. A 1uV signal can be
> > > equated to -107dBm and is 34dB less voltage&nbs p
> ;but 17dB less power. So on
> > > Rocky (or any others) I should see a 17dB difference between a 50uV
> > > signal and 1uV signal at the antenna terminals. Right ?
> > >
> > > 73 Kees K5BCQ
> > >
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