Fluke 87V Robustness Tests, Part 2

[@javierpallalorden]

Thanks for the video Joe, do you know when the 3.03 firmware was first released?

[@yl30]

Thank you!!! Excellent channel, I enjoy very much! Have you considered checking out the BK 2709B?

[@joesmith-je3tq]

I ran a BK early on. It did not do very well. I have not looked into any others they offer. Specs on this one seem fairly basic.

[@yambo59]

Hi - wanted to ask if the alligator screw terminals on your test box are stainless steel-? Im building a combination test box and a section of it will use similar screw terminals, didnt know if stainless screws or brass would be the better conductor - I know brass gets a patina so I was considering stainless or nickle/chrome type screws.

[@joesmith-je3tq]

My answer to Glen about the hardware and the errors it causes... So you are asking if the resistance of the mechanical hardware will add an error to these measurements. To that, yes it will. Describing it as "too much" and "very low" really don't carry a lot of meaning. For you, 0.5 ohms is a low resistance and is difficult to measure. For me, this is a very high resistance. What means too much to you again may mean something different to me. I am using the box to do quick checks of the meters. I need it to be accurate and repeatable enough to know if a meter has changed. That's about it. Most of the parts are better than 1% which is overkill for what I am doing. 2% would be fine. So how much does that steel hardware effect the measurement? We know P=RA/L, where: P = resistivity of the material in ohm-m R = resistance of the material in ohms L = length of the material in meters A = cross-sectional area of the material in square meters The hardware is all 304 stainless. The resistivity for 304 is 6.897E-07 ohms-meters. These are all a #8 which have a major diameter of 0.138" or 0.0035052 meters. We know the area of a circle is pi R^2. So that's 9.6497 um^2. The total length of the screw is roughly 0.5" or 0.0127 meters. We want to solve for R, so R=PL/A. I get 0.00091 ohms but I strongly suggest you check my work rather than trust my napkin calculations. So that's what, 0.2% error? Again, I may have made a mistake.

[@sepertude]

Joe at 1.00 you zeroed fluke while accidentally jumping across 0.1R instead of shortening the leads, thats why it was not accurate, please edit othervise 87V funs wont sleep tonight :D

[@joesmith-je3tq]

The resistance between the two common leads of the 4-wire sense resistors is fairly low compared to the part I am trying to measure. I actually show it compensated both ways. Note that both the Brymen and Gossen were compensated using the the two common leads as well. The specs on the Brymen are not very good and it is the wrong tool for the measurement. It does a better job than I would have expected.

[@joesmith-je3tq]

I have uploaded a few pictures making a 4-wire measurement of the common connections using my old HP bench meter. www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/2425/