Re: 2247A Is this normal?

Dan G

On Wed, Jan 13, 2021 at 03:10 PM, Tim / N8TIM wrote:

I have a 2247a and when I put it in the voltmeter mode and pick Peak to Peak
the cursers are not touching the peaks of the wave form. Is this normal or do
i need to get the service manual out?
Hi Tim,

The signal you are measuring seems to be close to 110 MHz, which is at the
BW limit of the 2247A. The exact vertical deflection bandwidth of the
scope is unlikely to be exactly the same as the bandwidth of the peak-to-peak
detector, which may be somewhat higher.

I have a 2246 Mod A (well-calibrated to the best of my knowledge), which
shows similar results when measuring a 110 MHz signal from the SG503.
In reality, the signal amplitude is somewhat greater than indicated even by the
p-p detector.

Do you know the actual amplitude of the signal you are observing? (A 100 MHz
scope cannot be used to accurately measure the amplitude of a 100 MHz signal)
At 100 MHz, one would expect a measurement error close to -3dB.

By itself, your photo is not necessarily an indication of any problems with your scope.
Are the cursors closer to the waveform peaks when you measure a 25 MHz sine wave?


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