David wrote: >How useful is this > >http://www.ebay.com/itm/281149723636 ? > >On the fact of it, the device would give one a reasonly high >confidence something is working readlably well. I wonder if that is >good enough for a 3457A. Let's assume that it is still working exactly the same as it was when it was calibrated. The calibration values are recorded to 4-1/2 digits. So the uncertainty is greater than the two LSDs of a 3457A. Of course, it is almost certainly not working exactly the same as it was when it was calibrated, which is going to put at least the third LSD of a 3457A in question. So it is good enough for a 3457A only if one is content with a 3-1/2 digit verification on a 6-1/2 digit instrument. Best regards, Charles

On 12 August 2013 01:58, Charles Steinmetz <csteinmetz@yandex.com> wrote: > David wrote: > >> How useful is this >> >> http://www.ebay.com/itm/281149723636 ? >> >> On the fact of it, the device would give one a reasonly high >> confidence something is working readlably well. I wonder if that is >> good enough for a 3457A. > > > Let's assume that it is still working exactly the same as it was when it was > calibrated. The calibration values are recorded to 4-1/2 digits. So the > uncertainty is greater than the two LSDs of a 3457A. Of course, it is > almost certainly not working exactly the same as it was when it was > calibrated, which is going to put at least the third LSD of a 3457A in > question. So it is good enough for a 3457A only if one is content with a > 3-1/2 digit verification on a 6-1/2 digit instrument. > > Best regards, > > Charles Thank you Charles. Yes, on checking the spec I can see it wont be any use. Dave