I have an Delta XP, running in H/D mode. I saw that box and trap current were very variable and thought that it was an ageing filament. I have changed the filament but am getting exactly the same. I switched to the triple collector (CO2, masses 44/45/46) and got a nice stable 0.78/0.71 mA.

The fluctutions in box and trap seem to start at a magnet setting equivalent to around mass 9 on the triple collector, and then get steadily worse down to the magnet step neeed for mass 2/3 on their cups, where the fluctation is over a range of about 0.2mA, with a period of around 14 Hz.

I have played around with some of the focus settings to no avail. Not quite sure how to interpret this, would be grateful for any suggestions. Are these just bad filaments, with poor performance evident at the lower magnet steps?

Thanks,
Simon