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E4440A preselector

Question asked by jeddahmike on Jul 14, 2012
Latest reply on Jul 19, 2012 by jeddahmike
Hi everyone,

I have a PSA E4440A that appears to have a problem that is corrected with the preselector. This affects all inputs over 3GHz. As an example, I input 5GHz @ -10dBm. Regardless of what I have the span set to, I can tell that the amplitude is reading low, around -35dBm. I center the frequency, and reduce the span to 20MHz. The marker reads 5.000000, with an amplitude of -35dBm.
If I hit the Presel Center, the signal jumps up to between -10 and -11 where it should be. The Presel Adjust on the right side menu shows 47.80MHz, where as before it read 0Hz. 
I have to go through this routine every time I change frequency. 
From what I read in the manual, and here on the forum, 1 or 2dB of shift might be expected, not the 25dB that I’m getting. I could be wrong.

I have two instruments that are doing this, and a 3rd that acts as normal, the amplitude is pretty close before hitting the Presel Center, and doesn’t change much after pressing it. So my question is if anyone knows whether this is a setting that got switched off, cal constants that might have been lost in a factory preset, an adjustment that can be fixed with a TME software adjustment, or if it is a hardware fault?

Thanks,
Mike  

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