In the last days I've set up an automated measurement measuring Prema2080 with K2182A, switching through all channels (1 to 40) and acquired quite some data.
Figure P2080-TEMF3: The relay card was fully covered in cotton wool, initial zero was done with a short at the scanner output, afterwards channel 1 (very left) to 20 were monitored (1000 samples per channel / 500s), at around minute 180 I connected the short again at the scanner output, then measured channel 21 to 40 (very right) and finally connected short at the scanner output again.
I then removed all of the cotton wool at the component side of the board.
Figure P2080-TEMF4: The initial zeroing was done with scanner switched to channel 1, each channel was monitored over 1000 samples (500s) before switching to the next channel and this for ten complete runs.
As can be seen there is quite some overall distribution and difference between the first 20 channels (connector X2) and the second 20 channel (connector X3). It can also be extracted that some channels are close to each other, so that they could potentially be used for reversal measurements of voltage references without contribution of large errors.
We can further extract that there is obviously some thermal gradient, so that improving thermals could improve overall behaviour. At least for channel 21 - 40 this can be directly correlated with the position of the relays inside the scanner, while on channel 1 to 20 it's less obvious.
Is someone experienced? Would a copper plate covering all relays improve thermal gradients significantly and thus TEMF?
Just for clarification, the scanner is fully within spec (typ. 1 µV, max 2 µV after 1.5 h warmup time), but I just wonder if it can be made behaving a bit better.
-branadic-