On Sun, Feb 2, 2025 at 08:09 AM, Rick Stanback wrote:
-33dBm
First question: did you use a 50 ohm termination on the scope? It appears you didn't. So the generator is putting out 10 mV into the 10 meg or so scope.
If you had a 50 ohm termination that would halve to 5 mV (the generator has an output impedance of 50 Ohms so the voltage would halve).
5 mV in 50 Ohms is .5 microwatt is -63 dBW is -33 dBm. That is spot-on.
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You are measuring a square wave on the scope. A square wave can be seen as the sum of infinite odd harmonics of a sinewave. The SA is only measuring the fundamental? sinewave.
Than the power in that sine is .707*5 mV == -66 dBW or -36 dBm. Or in a quick manner: -33 - 3 == -36 . -37 is well within the specs of the SA in your settings.
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Your measurements are correct.
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regards
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Henk
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