HP 3458A firmware revision differences

[matthuszagh]

I opened up my HP 3458A to replace the RIFAs and Schaffner filter. Because the instrument is already open, I'm thinking of taking this time to update the firmware. My unit has revision 7, but the latest is 9 (FYI, all firmware revisions are very helpfully listed here: https://xdevs.com/fix/hp3458a/#firmware). Is there a benefit to updating to revision 9? Are there any resources for how the various firmware revisions differ from one another?

[Dr. Frank]

Service note 12 contains descriptions of most of the Firmware updates.
Ver 7 to 8 fixes this very old PERIOD calibration bug, which I already found in 1990 on my first 3458A.
Therefore, it is reasonable to update to 8 or 9.
Ver. 9 only changes timing of one of the ACAL procedures, so you should use this latest version.
Check if you have a 6 EPROM board, or already the single EPROM one. I wonder if Illya also hosts latter version.

Also check the date code of the nv-SRAMs, whether they have to be replaced soon, at least make a download of the CALRAM.

Frank