Yep, ur right Don. A freebie Harbor Freight digital voltmeter appears to have a helluva lot better accuracy than reality. Digital calculators on the other hand, ARE accurate. This changes our mind-set, simply because we see all those digits past the decimal point on a dVOM.
it was better when we only had slide-rules to calculate things. Accuracy to more than three places was at best, a guess. Besides, what good does it do to arrive at a required by-pass capacitor's value of 0.0110987 µF ? 73, Charlie k3ICH -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Don Wilhelm Sent: Friday, November 30, 2018 9:56 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] [K3] SWR - Numerical Indication Petr and all, Those digital instruments that show 2, 3, or 4 decimal places have given us a false sense of accuracy. For instance an instrument that is accurate to 5% and has a 4 digit display can show us (when measuring a 5 volt source) anywhere between 4.750 volts and 5.250 volts and still be within the 5% accuracy window for the instrument. Review the specs and calibration for whatever meter you are using and do not expect those extra digits to be correct - in other words round the numbers displayed. Many wattmeters are only accurate to 20% of the reading - so if one wattmeter at 100 watts shows 120 watts and another shows 80 watts, the actual power could be 100 watts. Take that into consideration. The Telepost LP-100 when calibrated to NIST standards is accurate to 5% (it can be lower, but Larry will not guarantee it). So any power it displays between 95 and 105 watts can actually be 100 watts. In other words, look at the specified accuracy of whatever meter you are using and take that into consideration. Those extra digits on your meter may be meaningless. 73, Don W3FPR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
