KPA100 resistance checks
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Good afternoon all, With my KPA100 I am doing the resistance check on page 21 of the manual and for U1 pin 4 to ground I am getting 3.076 and not the 3.1 is this a problem? Mike VE3WDM ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Mike,
Nornally voltage measurements that are less than 5% away from their nominal values are just fine. In your case however, the target value was stated as having 2 significant digits - so just round your reading to 2 significant digits as well, Your 3.076 volt measurement rounds nicely right to the target value of 3.1 volts. /rant on Alas, when are those with many digits of display on their meter going to discover that just because the meter shows all those digits, many times (most times) those lower order digits are not always significant. If you are measuring something nominally at 10 volts and your reading is anywhere between 9.5 and 10.5 it is close enough to 10 volts (except in special cases. There is no sense fretting about it because the measured voltage is 9.899 volts instead of 10 volts. Do we get the idea - just round the value you measure up to the number of significant digits expressed in the nominal value. When do those extra digits become significant? Well, if you are measuring something that is supposed to have 1% precision, then 3 significant digits are called for - and add to that the fact that for most digital meters, the last digit displayed has a variability of +/-1 count, so in this case, 4 significant digits could be called for., but when we measure things in a circuit which uses 10% tolerance capacitors and 5% tolerance resistors, 2 significant digits are enough to consider, occasionally 3. /rant off 73, Don W3FPR Mike Weir wrote: > Good afternoon all, > With my KPA100 I am doing the resistance check on page 21 of the manual and for U1 pin 4 to ground I am getting 3.076 and not the 3.1 is this a problem? > Mike > VE3WDM > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by VE3WDM
I have been reminded that the original question was about resistance.
However, the same principle applies - if the measurement expected value is to 2 significant digits, then round your measurement to 2 significant digits. 73, Don W3FPR Mike, Nornally voltage measurements that are less than 5% away from their nominal values are just fine. In your case however, the target value was stated as having 2 significant digits - so just round your reading to 2 significant digits as well, Your 3.076 volt measurement rounds nicely right to the target value of 3.1 volts. /rant on Alas, when are those with many digits of display on their meter going to discover that just because the meter shows all those digits, many times (most times) those lower order digits are not always significant. If you are measuring something nominally at 10 volts and your reading is anywhere between 9.5 and 10.5 it is close enough to 10 volts (except in special cases. There is no sense fretting about it because the measured voltage is 9.899 volts instead of 10 volts. Do we get the idea - just round the value you measure up to the number of significant digits expressed in the nominal value. When do those extra digits become significant? Well, if you are measuring something that is supposed to have 1% precision, then 3 significant digits are called for - and add to that the fact that for most digital meters, the last digit displayed has a variability of +/-1 count, so in this case, 4 significant digits could be called for., but when we measure things in a circuit which uses 10% tolerance capacitors and 5% tolerance resistors, 2 significant digits are enough to consider, occasionally 3. /rant off 73, Don W3FPR Mike Weir wrote: > Good afternoon all, > With my KPA100 I am doing the resistance check on page 21 of the manual and for U1 pin 4 to ground I am getting 3.076 and not the 3.1 is this a problem? > Mike > VE3WDM > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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