Guys I've had an odd problem on the 2380 re TC with one build. I haven't noticed it before so it appears to be specific to this build, but I need to do further testing. Posting now so you can be on the look out.
I have a Titanium build in which is reading 0.47Ω at rest. However, as soon as I do TempCal Init to calibrate it, then check resistance again, it shows 0.49Ω / 20°C. The resistance then slowly lowers back down to 0.47°C - if I keep checking resistance ever few seconds, I can see it move from 0.49°C to 0.48°C to 0.47°C. The problem this causes is it's showing 20°C at 0.49°C, not 0.47°C, so once it has reached 0.47°C again, it now thinks it's at anywhere from 3°C to 10°C !
A simple workaround is to set my target temperature about 15°C higher than I want it. But of course this should not be happening.
There's a second strangeness which could well be related, and has already been noted by
@ndb70 in the past. Quite often when I calibrate and check temperature, the temp is not 20°C as the manual says it should be. Instead, it's around 23°C - but I have also seen as high as 26°C.
If I keep re-checking temp for a minute or two, it will gradually lower down to 21°C or 20°C.
I just tested a second Ti build, to see if I could re-create the problem described at the top of this post. I could not, but it did readily show the 23°C issue. 0.31Ω Ti build, I put it on the 2380 and check resistance a number of times to confirm it's stable at 0.31Ω. Then I Init, and check resistance/temp - it shows 0.31Ω still, but also 23°C. I keep checking Res/Temp and 0.31°C does not change, but the temp lowers slowly to 21°C after a minute or two.
All I can think here is that when you do Init, it is pulsing the coil very slightly. Enough to push its temperature up very slightly. Why it is doing that I have no idea. I think in the case of the first build mentioned, 0.47Ω, there's something weird with the build that's causing it to jump in resistance by 0.02Ω when it has that little pulse and that's throwing out the temp sensing completely.
I'm wondering if this pulse is meant to be about getting TC more accurate - it measures the base resistance, then it sends a tiny pulse to the coil, enough to increase the resistance by a few 0.001s - too little to be shown on the two-digit decimal resistance reading. It does this to.. I don't know, use the coefficient to calibrate what 1°C means for resistance rise? I'm really not sure why it would need to do that, it can just assume current resistance = 20°C and then use the coefficient to predict future temperatures.
The manual indicates that calibration will always be done for 20°C, and even says "if after calibration it doesn't show 20°C, do it again." It says nothing about it pulsing the coil - either in the manual or in the Application Note.
Update: I had taken the 0.47Ω build off the 2380 and put it on my SXK, checked it vaped Ok there, then put it back on the 2380. Now it's back on the 2380 I repeated the Init, and the problem was present again but not nearly so badly - This time, after Init it initially showed 24°C and that quickly settled to 20°C, was at 19°C for a couple of minutes, and is now at 18°C. This time rather than rising from 0.47Ω to 0.49Ω, it showed as 0.48Ω / 24°C and now shows either 0.47Ω / 18°C or 0.47Ω / 19°C.
Very odd. Tomorrow I will see if I can probe an atty with my DMM to see if it applies a voltage when calibrating.