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Originally Posted by Skywave
In the attached article, the max. and min. voltages shown on those DMMs are 10.21 and 9.85. That's a difference of 0.36 v.
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Quote:
Originally Posted by G0HZU_JMR
But is that realistic? I've worked in RF labs all my working life. I see lots of DMMs and lots of test gear and it's rare to see a DMM that gives a duff reading like that.
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"Is it realistic?" you ask. I don't think that's the point; it's not relevant. The picture in the attachment is simply the author's illustration of
why (in his opinion) one should have the means - and use that means, now and again - to check the calibration of an item of test gear.
I've worked in many RF labs. myself during my pre-retirement years - as have you. (From your location, it seem likely that you and I have worked in the same establishment). So you and I both know that it is usual to not only find the very best test gear in such places but that such test gear is always religiously re-calibrated on regular intervals and to very high standards. And that costs lots of money. In this thread, we are talking about a typical home-based D-I-Y enthusiast's workshop - and with a very limited budget: expensive external re-calibration services are out of the question for many of us.
Quote:
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However, I think the point I'm really trying to make is to advise people not to wander into the ivory tower world of the 'volt nut'.
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I am not an obsessive about accuracy, precision and resolution in measurements; I cannot speak for others. I take the simple attitude that those three parameters should always be in proportion to what the purposes of those measurements are for. But as I stated earlier, the ability to restore one's confidence in an item of test kit - especially if the cost of being able to do so is small in proportion to the benefit thus gained - seems worthwhile.
Al.