Does my E4406A VSA Series Analyzer have a 14-bit digital IF or a 12-bit digital IF?
All instruments that were manufactured in Malaysia were originally built with 14-bit Digital IF assemblies. Instruments manufactured in the US that have Serial numbers US41513009 and later were also originally built with 14-bit Digital IF assemblies. Also, U.S. instruments that have serial numbers that start with US4136 and have the following suffixes were also originally built with 14-bit Digital IF assemblies: 2964, 2977, 2982, 2986, 2987, 2988, 2989, 2990, 2991, 2992, 2993, 2998, 3000, 3003, 3004, 3005, 3006, 3007. All other instruments with serial numbers US41362959 and prior were originally built with 12-bit digital IF assemblies. The date at which instruments started to be manufactured with the 14-bit Digital IF was approximately January 15, 2002.
You can also determine which digital IF assembly you have by looking at the Show System menu which is accessible by pressing the following key sequence on your instrument: