I recently got a 500+ unit with two tubes, but both are different - one is clear glass type, a mini 4011 I guess. The other is black - either dark coated, or similar. Are these both the same, or different tubes?
I see in the calibration options, there are two settings for tube #1 and one for tube #2... interesting... ZLM, any additional information to share here? Love the new unit though!
A2
The more I learn, the more I realize I do not know!