是不是历史上第一台手持数字万用表还不得而知。
Fluke 8020A Digital MultiMeter.
On the right, you see my first digital multimeter (DMM) which I bought in 1980 at Piet Kennis in Tilburg. It was not particularly cheap, but it was a Fluke and in those days that meant:
Extremely robust. Drop it off a table and it still works.
Accurate, due to the double slope integration.
Complete: DMM, manual, probes, quickref card, soft vinyl carrying case.
All ranges protected. Plug it in the mains while in the 'Ohms' range and nothing is damaged in the meter. It just says 'Overflow'.
Battery operated, with a long battery life
LCD panel instead of LED's
It measures conductivty in the 200 nS (nanoSiemens) range.
Add it all up, and the NLG 450 (EUR 200) 1980 price tag was not that high. You still pay a similar amount for a good DMM nowadays.
The only problem with the machine was the LCD. It turned slowly black after a few years of use. I applied the heater trick, the freezer trick but in the end, the LCD remained unreadable.
So in 1995 I ordered a new display in the US. SInce then, it has worked as it did before.
The Fluke 8020A does have a few disadvantages, compared to modern DMM's:
Small 13 mm display (my other DMM's have 20 mm or more)
No bargraph
Not autoranging
On the other hand, it also has some clear advantages over the 'competition':
Very constant
Very reliable; even with a depleted battery there are no errors
Lots of functions and ranges
All in all, I am very fond of my Fluke 8020A. It was made in my the town I live in now, so that ought to make me a bit proud as well.
|
发表于 2010-2-9 08:44:42
提升卡
置顶卡
变色卡
楼主
发表于 2010-2-9 10:29:12