I cleansed the rotary switch contacts and now it works really well. It's linearity is good but the unit is uncalibrated. But I'm happy. The only problem I have is the current limitation, its not so stable. If I look on the schematics, its probably temp drift in the shunt resistor or the pot, as they are "non ovenized".
This photo is the trend plot of the time to roughly thermal stabilize. The total vertical range is 200uA and the horizontal is 7 hours 58 mins 40 secs. ...
I will try the same thing on a 2005A next.
Wow, I didn't know you could actually see the curve on the bench meter itself, pics worth 1000s words. Those are great results too, BTW.This photo is the trend plot of the time to roughly thermal stabilize. The total vertical range is 200uA and the horizontal is 7 hours 58 mins 40 secs. ...
I will try the same thing on a 2005A next.
I cleansed the rotary switch contacts and now it works really well. It's linearity is good but the unit is uncalibrated. But I'm happy. The only problem I have is the current limitation, its not so stable. If I look on the schematics, its probably temp drift in the shunt resistor or the pot, as they are "non ovenized".
MBY, how unstable is the current? I am seeing about a 1.4mA variation on a 200mA setting on one of my 2005A's on initial testing. (not completely stabilized yet)
Regards, robrenz
Wow, I didn't know you could actually see the curve on the bench meter itself, pics worth 1000s words. Those are great results too, BTW.
So, in a few hours I will check it again (the time is 01 AM here in Sweden, so the 2005 can warmup during the night (as can my DM3061 and Fluke 45), and I will check the current tomorrow).
So, in a few hours I will check it again (the time is 01 AM here in Sweden, so the 2005 can warmup during the night (as can my DM3061 and Fluke 45), and I will check the current tomorrow).
From what I have seen so far it appears it takes quite a while for the shunts in the meter and PS to thermally stabilize with a given current setting. The trend plot of the 2010 was 8 hours before it was reasonably stable. The drift in that time was 200uA. The drift after that was only 18uA. So it appears that when you are doing current measurements in CC mode (that generate heat in the meter and DUT) it is easy to confuse instrument and DUT thermal stabilization with DUT long term drift.
what are some practical reasons for a PS this stable?
what are some practical reasons for a PS this stable?
what are some practical reasons for a PS this stable?
So, in a few hours I will check it again (the time is 01 AM here in Sweden, so the 2005 can warmup during the night (as can my DM3061 and Fluke 45), and I will check the current tomorrow).
From what I have seen so far it appears it takes quite a while for the shunts in the meter and PS to thermally stabilize with a given current setting. The trend plot of the 2010 was 8 hours before it was reasonably stable. The drift in that time was 200uA. The drift after that was only 18uA. So it appears that when you are doing current measurements in CC mode (that generate heat in the meter and DUT) it is easy to confuse instrument and DUT thermal stabilization with DUT long term drift.Yes, there are lot of error sources. What I do now is to feed 200 mA through my DM3061 from another PSU to warm the measure shunt up. And my 2005 is "idling" on a setting of 10.000V with no load. My goal is to see the drift of the 2005 shunt/CC-circuit when "everything" _except_ the CC-circuits is loaded/warmed up.
Excellent! That measurement is more relevant to everyday use than the long term fully stabilized multi day stability.
Max Min Avg Smpl
LSP-1403 150.5309 150.4018 150.4949 17420
PD 2005 147.5291 145.7476 146.1012 100
PD 2005 147.5291 143.3662 144.3162 15970
PD 2005 145.1924 143.3182 144.0457 8820
(Every row with 2005 is a cleared of max-min, to see if things improve after warm up of the CC circuit)Wow, I didn't know you could actually see the curve on the bench meter itself, pics worth 1000s words. Those are great results too, BTW.
From what I have seen so far on the 2005A the CC output is much more temperature sensitive than the CV output. My first step will be to replace the current sense resistor (R26 in the 2005A schem.) that is in the CC control loop with a much lower resistive temp coefficient and higher wattage. Just holding your hand on top of the PS for a minute will spike the current. The 12 mA droop in this picture is from a gentle blast of compressed air for just a few seconds directed at the top of the PS.
BTW your english is great. It is infinitely better than my Swedish.
Having a hard time ... deciding whether the fluke meter is a multimeter or a very slow scope