Hi, this is my story with it:
About a month ago I received it. A big heavy (4 pounds) box. A funny thing that on one side there was a comparision with the fluke 87 and the 867. The 87 had almost nothing compared to the other two although I still think that it is a legendary exellent dmm.
I take out the unit. The body seems pretty strong and hi quality. The nicads were charged so I could play a bit with it instantly. Then, when I plug the charger I hear a hiss noise and smoke comes out... (Not bad for 1 hour used product) But everything kept working; It just didn't recharge the nicads. So I open the unit: The first surprize I get is the poor quality of the plastic. i just didin't noticed it on the outside. Close to the power jack was a big smt 100nf cap (maybe a power filter). It was destroyed. So I begin to phone every electronic store and realize that I can't get there by car (I'm 16, no car yet) and even if I could I don't have even a soldering iron (Everything is where I live, but I came to Boston for the summer. I decide to mail the company and ask for a replacement. They were really nice answering and sent me a new box. When I take the "new" 440 I realize that they sent me a used one (didn't like that very much), it was worn and scrachted on the borders, the inscriptions on the keys were worned out... What I dis was I replaced the mainboards. Meantime I could observe closely the interiors of these: there's a beautiful lcd module:
160*240 with backlit.Anyways back to the thing. The manual is horrible (30 small pages which explain all the available accessories, just kidding) When I turned on the dial to first pos (VDC) appears (from up to down) with huge letters the value mesured ( 4000 counts, 0.1 mV min res). Then with smaller font goes the frequency ( sadly the freq counter in this mode (VDC) displays me 0hz when I apply logic cmos signals(0-5V) )And then there's the scope: Up from the waveform appears the trig level (-20to+20). On the right, the vert sens (which, opposedly to the voltmenter has a min sens of
0.1V, pretty disappointing). On the bottom horiz sens (1s/div-1us/div) and the slope (inverted or original) The wave form hold on a rectangle of 4*6 squares (divisions). Sadly the waveform refreshes slowly (2-3 times a sec) so its impossible to monitor pulse trains for example, but for steady signals its great. Then in the bottom there's the menu. (5 choices)-rel measurment (you set a standart, and it give you the variance from the value mesured)
-peak hold
-frequency or period
-full auto indicator
On the keyboard there are first the menu keys then the DMODE key: it enters a menu where you select to 1) use the display combo (scope+meter) or the meter alone. 2) the scope menu where you can adjust the trig, timebase, take a singleshot or enter glitch capture
3) the trend menu: sampling time (1sec-3min), enable rs232 output(I'm still triying to find the algorithm used), restart the measure. (I tested this mode taking a sample each 2 second on a charged capacitor, the curve was wonderful, I imidiately loved this trend feature) Still with keys: next there's a hold key, it simply freezes the display. A big RGE key, you surely wonder what it is A big PROG key: in the entered menu you have a REC (record) key (I don't exactly know the sampling time, you can't choose it)which tells you current value, max,min,avg I don't exactly understand the working of it: if you put a very variable signal, the average changes very often then the buffer fulls very fastly (10 sec) but if the signal is slow changing then the buffer lives for some minutes. Then there are rel (see above) and a comp,(compare): you set hi and lo and it tells you if the value is in between higher or lower.Still with keys, there's a mem key: wave mem: (you can store 8 screen shots) and setup mem: you can store 8 different configs. The configs include lcd contrast, display (combo or meter alone), rel reference, hi and lo limits (for compare) rs232 baud rate (1200 2400 4800 9600). (for rel hi and lo, you set the values in the prog menu and can store them in setup mem)
Next there are 2 small red keys: backlit and HELP; really impressive feature for new people but completely useless, it give you for each mode where to connect the leads and a text: Warning: never attempt a voltage measurment above 1kV...
Time to switch the mode, in ACV, everything is the same (forgot to say that the freq counter is 5 digits) In Hz mode, in huge letters appear the freq (rge from 100hz(0.01hz res)to 2mHz (100Hz res)) , under it the period (exellent to have both) and the same scope window (although I don't know if it's on ac or dc). Or if you choose not to display the scope 2 new things appear: duty cycle and pulse with (beautifull)(again not mentioned in the manual). There's a beatiful feature: in trend mode horizontal is still time, but vertical is HZ!!!!! I love that. (rel, rec, comp is not available for frequency)
Then I change to diode: You connect a diode between 2 leads (the polarity doesn't matter) I think it sends 3 volts between it and it tells you 2 other voltages, one in direct one in reverse. For a normal
1n4001 it told me 0.6V in direct and infinite resistance (here it's "OUCH") in reverse. I'm sorry I can't describe better because I don't really understand how it works.The resistance mode is pretty complete: cont check, rel, rec, comp modes. Also trend is Ohm/time.
The current modes are really similar to voltage modes, just that everything is current: even the scope displays A/Time. Also I like very much the 0.1uA resolution...
The logic tester is a bit useless for me, you select between 3 logic levels (ttl, 3v cmos and 5v coms) all it does is display frequency and if its logic hi or lo
Capacitance is also not to nice, specially because of the sensitivity: .1 nf Trend mode displays cap/time.
Finally the component mode, I love it: It's a real component tester, you set the frequency to 2 20 or 200 hz. (I have it on 200hz always and it works flawlessly).
I think that I said the things I like/dislike but I will tell the things I would change:
-refresh speed of the vaveform (I think all DSO suffer from this)
-add bandwidth
-to remember the last configuration on the mode before power off
-have trig controlls much more accessible, or make auto triggering
-improve the cap meter (it is really nasty)(add inductance meter, display the Q curve... somehow what a specialized LCR meter does.)
-make a more reliable keyboard
-add dB
-improve scope sens (same as meter sensitivity)
-add trend to the logic alnalyzer
-maybe improve the manual?
I like this scope very much, it will certainly not replace a bench o'scope, but I don't have the money for that. So I think that for the price it costs, its exellent.
Hope you enjoyed my review Dimitri