...as measured and proven by Pickering, hp in their drift - AN18A,
Would you please link the publications/pdfs you are refering to? Thanks.
-branadic-
I refer to the patent of Pickering, and his explanations on the 7001 reference.
AN18a should be well known, so I don't put a link here. You just have to extract from that AN18a, that the 3458A may basically suffer from hysteresis, if left unpowered (which is not included in the specifications).
branadic, when you have measured my LTZ #3 last January, it was quite cold, below 0°C, during the transport. You see the graph before, and after this ring comparison, and over the following year after initialization, referenced to my home 3458A and 5442A. Latter seem to be constant within < 1ppm.
This #3 reference made a hysteretic jump of about +1ppm, due to the low temperatures, which is obviously a permanent, and constant one.
You also see two baseline points for the 3458A, the first is from acbern, the 2nd is taken recently at the Hannover Maker Faire, using this same #3 compared to the PTB 3458A.
The ring comparison before/after the transport to the Maker Faire shows no change, in contrast.
This event, and several others, support my own experience with hysteresis behaviour of the LTZ1000 device, at sub-ppm level, even w/o JJA.
Frank