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8753D/E/ES/ET Source ALC Linearity

Question asked by dhamilton on Jan 10, 2013
We have several 8753's w/opt 006. F/W versions are various including latest versions per CPU.  We have an issue of the Source failing ALC power linearity above 3 GHz.  In the performance of TEST 47 Source adjustment, the unit will align the flatness across the band and only perform detector linearity of -15 dBm, -5 dBm, 0 dBm and +10 dBm @ 50 MHz only.

The problem is the RF source has two different ALC modulators for one detector.  

This is causing the the ALC linearity to pass up to 3 GHz and well within specifications, but fail half the time above 3 GHz. 

We get an error of nearly -.3 dB @ -15 dBm; +.25 dB @ +10 dBm; +/- .02 dB @ 0 dBm @ 6 GHz.

Is there a secondary adjustment not in the Service Manual that can correct the ALC linearity above 3 GHz to get these sources to pass specifications of +/- .2 dB to +5 dBM and +/- .5 dB +5 dBm - +10 dBm?   How was this instrument able to ensure ALC linearity above 3 GHz when that part is not aligned by the automated test?

Dr. Joel,  I hope you can shed light on this.