Marco,

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The gain and attenuator control lines are A1, A2, A3, A4 and A5 for the attenuators in the A12 module.

G1, G1 and G3 in the A12 module for the gains, and G4, G5 and G6 in the A14 LOG amplifier.

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Between CORR ON and OFF, in my case, there is a 6 dB difference, and it is in A12 that there was the change for 6dB.

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If the REF Level changes, then the attenuators and gains will vary in A12. For A14, nothing changes.

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The behavior of your 8591E is very strange.

If the A12 module had only a 1dB attenuator enabled in CORR mode, then in CORR=OFF mode, there would be only a 1dB difference.

But this would mean that the level arriving at A12 would be low normally, but you have -5dBm, you should have a 10dB attenuator enabled, and this does not seem to be the case.

And in no corr mode, the noise increased by 10dB...weird.

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Yves