Would be nice, to get pre-selected parts from some ebay sellers
Hello,
keep on dreaming.
In my dream world the manufacturer sends
all his production of LM399s to his primary precision instrument manufacturer.
This one selects out the best parts and stamps his personal number (something like 1826-1249) on it.
The rest of production is sent to the other instrument manufacturer.
He selects out the best of the rest and marks them. (with something like SL40057).
(that is my personal explanation that I already found three instruments of this manufacturer which have more than 5 ppm difference when tilting from the left to the right side whereas the other manufacturers instruments have below 5 ppm tilting effect from back to front side (the same orientation regarding the LM399 on this instrument)).
The rest is then sent back to the IC manufacturer and is stamped with LM399.
So how can you tell me that someone will get those LM399 at the sweet spot.
The most probably reason that I have some of them is that I all bought them when NS went out of production. So the manufacturers all selected among the LT parts at this time.
I have put several measurements into one single graph.
With best regards
Andreas