Alex,
Yes, that is the way Hp did serial numbers back in the 70s and 80s but do not know if Agilent kept the tradition.
The 4 X 5 serial number of instruments had the following scheme:
? ? ?1234A67890
Year of manufacture =? add 60 to first two digits? ==>? 12 + 60? =? 1972
week of the year of manufacture is the next two digits? =? week 34 of 1972
Letter is country of manufacture:? A = America? ?J = Japan? ?M = Malaysia? etc.
Again you are correct about the Ohms calibration:? 2 Wire or 4 wire but not both.? ?
This was a tough decision to make because of a gotcha.? The gotcha was cost and room for more parts.? We simply ran out of room in storing the firmware and cal constants for? BOTH? ohms functions.? To store more cal constants kicked us up into another chip for memory and COST was a big deal on this project.? Memory was not cheap back then. Besides, there was not enough room on the 3468A motherboard (just one PCB was allowed) for another memory chip without squeezing other areas and compromising analog performance.? I did look at that but just could not make it fly.? There are strict requirements regarding spacings with AC mains and any voltages greater than 42v on a motherboard that also reached out to the outside world (thru the input terminals) that a human could touch.? These spacing requirements eat up a lot of realestate on the MB.? Just was not possible unfortunately.??
Another thing to keep in mind is that the 3478 has an extra range on DCV and Ohms that the 3468A does not.? The 3478A has a 30mV and 30mOhm range that the 3468A does not have.? The 3468A has the capability to implement these ranges ( the switches are there for appropriate signal conditioning and amplifier gains) but the firmware does not allow it.? This was a marketing decision to further differentiate the 3468A and the 3478A from one another besides the 78 being a systems meter with F/R switch and HP-IB interface to justify the cost difference between them.? With appropriate firmware the 3468A could have those lower ranges.? I might have a copy of some special firmware I used that turned on those functions to do some testing on the 3468A but that might take some looking.
George
