I've been fooling with this as I calibrate my Maverick temperature probes so I can take readings using an Arduino. I haven't gotten mine to read below 34°F using ice cubes in an ice water bath. An insulated cup might help. I was using a pyrex sauce pan. Crushed ice would also help, but my attempts at such using a meat tenderizer on a cutting board did not go well. :roll: Use as much ice as possible with just enough water to cover. Stir vigorously.
If you have an ET-732 you can swap probes. Can't do that with the ET-73 as the probes are different.