187跟87-IV的分别
87-4/89-4 to 187/189 ComparisonAdded 50 Megohm and 500 Megohm resistance ranges (still has conductance mode which will still read to 100,000 Megohms but as the reciprocal).
Added longer Pulse Width and Duty Cycle measurements down to 1 second (versus 50 milliseconds)
Added CAT IV 600V Safety rating in addition to the CAT III 1000V Safety Rating
Faster meter response especially in the Dual Display AC and DC mode and 500 ohm range.
Now has a real time clock (versus a elapsed time clock) 189 only
Test lead compensation can now be done on the 10 nano Farad capacitance range as well as the 1 nano Farad range.
Has improved performance in high EMI noise environments such as around adjustable motor drives.
The 87-IV and the 89-IV had a Pulse width measure range that only when down to 50.000 msec. The 187 & 189 Pulse width increased to 999.9 msec.
The 87-IV and the 89-IV duty cycle had a resoltuion of 0.1% and improved to 0.01% for the 187 & 189. Both the older models and newer models only were selectable from 10 to 90% These spec's are shown on page 7-10 of their respective user manuals. 洋文 看不懂啊。翻译成中文就好了。 87-4/89-4到187/189的比较
新增50兆欧及500兆欧电阻档（仍具有电导测量通过取倒数读到100G的功能）。
更长的脉冲宽度和占空比测量。从50毫秒增加到1秒。
安全等级从CAT IV 600V增加到CAT III1000V。
更快的仪表响应，特别是在双显示交直流模式和500欧姆的档位。
189具有实时时钟。
10nF以及1nF电容测量档位具有测试导线补偿。
在高EMI噪声环境中仍能保持高的性能，例如在可调速电机附近等环境。
87-IV和89-IV脉冲宽度测量档位低至50.000毫秒。 187及189脉冲宽度测量增加至999.9毫秒。
与87-IV和89-IV相比，187和189的占空比分辨率从0.1％，提高了0.01％。无论是旧型号和新型号可选范围从10％到90％，详见各自的用户手册7-10页所示。 学习了。 貌似“与87-IV和89-IV相比，187和189具有0.1％的占空比分辨率，提高了0.01％。”这里翻错了
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phoenix2005:貌似“与87-IV和89-IV相比，187和189具有0.1％的占空比分辨率，提高了0.01％。”这里翻错了 (2012-03-0412:20) images/back.gif谢谢指教，已做了改正。
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