3421A CAL RAM

[Hans Brueggemann]

currently away from my 3468 and also not in possession of a 3421, but CAL ram error most likely points to a flat CAL ram battery (at least true for 3468), and therefore, it's very likely that the CAL data are already lost. You may want to check that first. you may want to post your question in the eevblog forum's repair section. The folks over there are toying with all kinds of vintage equipment and have already helped me out many times. They can probably provide you with the proper command sequence and a set of CAL data for your 3421. That won't bring back your instrument to factory accuracy level, but would at least allow you to exercise it, before you are doing a full cal & adjustment.