As noted in another thread, I want to replace a battery in a 3457A that has not been replaced in at least 11 years. The instrument has not been calibrated in that time either. At the time it was purchased from a dealer, I was told it was within specification, but if I wanted it calibrated I would need to pay. I never did have it calibrated, so have no historical data about this. I've no idea when it was calibrated, and have no cal certificate, so have no idea of the errors at the time of calibration.
I now want to change the battery, *and* send it to Keysight for calibration - I have a healthy skepticism of 3rd party labs, so would rather pay more and get the job done by Keysight. I'm wondering if I would be better purposely removing the battery, and putting a short across the SRAM so I ensure the contents are definitely lost. My logic is that 1) If I send it to Keysight and the cal data is corrupt, they will set the meter correct. 2) If sent to Keysight, with the cal data in tact, then if its within specification they will not adjust it. So if the limit on some parameter is 1%, and the error is 0.5%, then it will not be adjusted. But if the SRAM is corrupted, the error will be huge (if it will read at all), so it would force Keysight to adjust it to the correct value. At that point the error should be effectively zero given its a 6.5 digit multimeter, which means the uncertainly in Keysight's measurements should be much lower than the uncertainty of my meter. So by corrupting the SRAM, I should get a meter returned to me that is more accurately calibrated than if I take the trouble to preserve the SRAM contents. 3) The adjustments are I believe software, so there's no risk that adjusting potentiometers will cause drift to increase. 4) I don't have any historical data from cal certificates, so even if I a range is in error by 0.5%, I can't make any attempt to estimate the drift over time. Clearly if I had cal certificates over a period of years, I maybe able to get some idea of how the instrument is drifting, so possibly correct for that, if it is drifting in one direction. Thoughts? Dr. David Kirkby Ph.D CEng MIET Kirkby Microwave Ltd Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, UK. Registered in England and Wales, company number 08914892. http://www.kirkbymicrowave.co.uk/ Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please) _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.