Issue is not present on any of AC functions (ACV/ACDCV/ACI both fine, any range), as well as freq/period. Also if I set NPLC let's say 1 or 100 on AC functions, it seem not changing, and speed is still same. Is there any other settings need to be done for AC NPLC to work?
I'll order some comparators and perhaps make that agilent-bodge from your picture in other thread.
Seems finding modern comparator with supply >18VDC and <40ns is a real next to impossible, according to my search on Linear,Digikey,MAXIM,TI :/
If I use 0.001 NPLC or faster, no error. If use 0.01 or slower, errors. Let me make a video.
I think it's because HP's ADC using only integration runup method to resolve on those speeds, and rundown used only for more precise measurements.
Hi TiN,
NPLC works differently for ACV, and it also depends on the ACV mode (3 different!) used. Resolution is limited to 6.5 digits, in any case.
See manual, command reference for NPLC, p. 6-67, Remarks.
You may choose the different modes for ACV and see, if that changes something.
ACV also uses a different A/D input path (AC_AD vs. DC_AD, see CLIP).
The conversion anyhow, should or may be using the same algorithm, so maybe the problem is not with the comparators.
For faster conversions than 100us, there is a difference in the conversion algorithm, see hp journal 4/1989, p.13.
Maybe you fiddle around with the aperture parameter, and determine, when the error occurs.
Do you use ACAL frequently?
This is the most important function of this instrument, it will help, if you engage that function after your recent calibration, or after big temperature changes.
Frank