Products > Test Equipment
UT61E drift and recalibration
don.r:
The PTC doesn't need to be changed unless you are going above 600V which I believe is the minimum breakdown for them (WMZ11 75HV). There are mounting holes for the GDT/SG/MOVs already next to the PTC (as you can see in the teardown) but I'm not sure how the added components, especially the MOV, will affect capacitance. I'm not terribly fussed as I have a dedicated cap meter already.
I think a lot of the drift was down to VR1 constantly moving out of cal from vibration, a 20ohm change at 1%. I'll look at things longer term once I get the 200ohm Bourns in there.
sorin:
--- Quote from: don.r on February 05, 2014, 02:32:46 pm ---An Amprobe AM-270 for high voltage use or a used Fluke.
GDT = Gas Discharge Tube. You can use those or spark gaps or MOVs. Spark gaps and GDT operate at 1KV and above usually and I have no plans to take this meter anywhere near there so I'll stick to a 275V MOV (clamps at 600VDC).
--- End quote ---
Thanks, don.r!
I think that MOV-s are inadequate for UT61E, because you lost the hight impedance input on mV range.
You can find GDT down to 70-100V.
don.r:
--- Quote from: sorin on February 05, 2014, 03:23:28 pm ---
--- Quote from: don.r on February 05, 2014, 02:32:46 pm ---An Amprobe AM-270 for high voltage use or a used Fluke.
GDT = Gas Discharge Tube. You can use those or spark gaps or MOVs. Spark gaps and GDT operate at 1KV and above usually and I have no plans to take this meter anywhere near there so I'll stick to a 275V MOV (clamps at 600VDC).
--- End quote ---
Thanks, don.r!
I think that MOV-s are inadequate for UT61E, because you lost the hight impedance input on mV range.
You can find GDT down to 70-100V.
--- End quote ---
Is that due to the capacitance of the MOV? I'll dig a little deeper into the GDT.
sorin:
Its about the leakage of the MOV.
Nuno_pt:
Hi,
Are the components 0805 or 1210 imperial?
Don't have anything to measure and I'm not use to work with smd.
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