Marco,

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For my 8595E, module A12, after power on, if CORR=ON, IFA1-A4 are OFF and IFA5 is ON.

From this point on, only when the REF LEVEL is at 0, +10, +20, +30, +40, +50 and +60dBm, IFA5 is ON, all other cases, IFA5 is OFF.

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If I put CORR=OFF, the level read from the 300 MHz calibrator is -13dBm.

So, I put an external fixed attenuator of 6dB, for a level of -19dBm, and I did a CAL AMPTD.

I looked if IFA5 becomes ON by testing the different possible REF LEVEL, but this did not change anything in the previous results.

Either the attenuation values ??are predetermined, or, A12 is tested in relative mode from the external calibrator, that would be the reason why this did not change anything.

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On the other hand, the fact of having reduced the signal from the 300 MHz calibrator, changed the value of the gain at the third converter output: REF LEVEL CAL.

It is a variable gain amplifier controlled by DC voltage. This calibration is done in the first minute of the CAL AMPTD calibration.

Yves