Oh, it is like detective story, isn't it?
Joeqsmith, please please for the last time, Fluke 87V and 289, manual range!
I wonder if that "discovery" by user hgg in thread "A-look-at-the-uni-t-ut210e" regarding Brymen meters is truth, can someone confirm that (Lightages ?)
I dont want cross-link, but I am talking about "Reply #304 on: October 28, 2016, 08:30:20 PM" and following posts (where he shows that mV AC range does not indicate an overload at specific AC signal with DC component).
I was sort of before buying BM869s for my Christmas gift , but now I hesitate a little.
Would it be possible to fix that eventually by firmware upgrade at home?
Or is it not problem at all?
Well, I just tried with my HP3456A. It behaves well in all my tests and I cannot find fault with it.
If I put it in the 100 mV DC range and feed it 100 mV DC it indicates correctly. If I now add a 1 V RMS AC signal on top the meter shows OL. However, if I switch to the 1 V DC range I again see 0.1 V.
Conversely, if I switch to the 1 V AC range and feed it 1 V AC it shows as such. It shows OL if the voltage is increased above 1.2 V.
Now if I keep the AC voltage at 1 V and add a DC bias, nothing happens to the AC reading. Even if I add 20 V of DC bias, the AC reading remains unchanged to the full display resolution.
So as far as I can tell, the 3456A either shows OL, or it autoranges if enabled, or it shows the correct reading. Nothing I tried could induce it to show an incorrect value on the display.
Good to know. Of course, now I need to run my old bench meter like you asked me to in the first place. This meter is the same one I show in:
https://www.eevblog.com/forum/testgear/bm235-variability/
Again, bought it brand new from HP and has never been aligned. The DC is effected by the AC level. But the AC is not effected by the DC level.
This meter replaced my HP3468A which I also bought brand new from HP with that old HPIL bus. I had it cal'ed in 2002 but it has never been aligned. This meter for what ever reason does not appear to have this problem. In manual range it just over ranges. So the cheapest meter I think I have bought and the most expensive one don't have a problem. I wonder about that HIOKI....
So my Made in USA old HP meter comes out on top of my heap for this test anyway. Not a bad meter except I was ignorant about HPIB at the time and was not able to predict it's future..
Good to know. Of course, now I need to run my old bench meter like you asked me to in the first place. This meter is the same one I show in:
https://www.eevblog.com/forum/testgear/bm235-variability/
Again, bought it brand new from HP and has never been aligned. The DC is effected by the AC level. But the AC is not effected by the DC level.
On the 34401A the DC readings are influenced by the amount of AC present?
So the 3468A behaves better than the 34401A?
Which is the most expensive meter, the 3468A or the 34401A? I would have guessed the 34401A to have cost more than the 3468A based on features and year of manufacture.
I think now you have your answer?
The problem exists with many meters, not only with Brymen.
With knowledge of where and how the problem can occur, you can make sure to avoid it (for example, by always measuring on a higher range first and then down ranging when you know the voltage magnitudes).
This would not be a good reason to hesitate about buying a BM869s.
I probably will purchase BM869s, but am a little bit disappointed.
Thank you all again.
That thread https://www.eevblog.com/forum/testgear/the-uni-t-ut139c-and-my-power-supply-ripple/ concerns probably similar/same issue.
It seems, that higher rank Flukes (87V, 185, 189, 289) do not suffer from this issue.
In this respect Brymen does not stand out from the crowd of common meters, unfortunately.
Price difference tell that.
I probably will purchase BM869s, but am a little bit disappointed.
I do not have any detailed data, my guess is based exclusively on that thread ...
I already have asked you, I thought that (after your videos) Flukes 87V and 289 you have at least available from your friends.
Thank you in advance!
(I learned many things from this thread)
What data for the Fluke 185 did you not understand?
Fluke 185 50,000 count
500mV manual range
test waveform: Sine 480mVAC 9VDC offset 60Hz
Selection:
AC: 487mV 60Hz
DC: OL
AC DC: OL - mVAC
AC+DC: OL - Hz (60Hz with < 1VDC offset)
Auto range mode has no discrepancies:
AC: 0.489mV 60Hz
DC: 09.07V
AC DC: 09.04V 00.49V
AC+DC: 09.06V 00.00Hz ( 60Hz <4VDC offset)
I already have asked you, I thought that (after your videos) Flukes 87V and 289 you have at least available from your friends.
Thank you in advance!
(I learned many things from this thread)