Vahalla Scientific EN2500 Calibration

First off let me say THANK YOU to all that have joined the lab and helped us get there we are today. Content is based of viewer questions and comments. And will continue to be. In this case this upgrade is so we can do some testing as requested by viewers specifically on 10Mhz references. So as always more is on the way.
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In this video we take a second pass at the 2500 EN this time we need to calibrate and Align the unit that was found to be out of specification in the last video. So after getting some resisters to use as loads in the lab and leveraging some Ohms law to help up bring the EN2500 up to specification.
** Repair exposes the Tech to mains electric and should only be done by trained personnel. Errors can be fatal. **

[@jenniferwhitewolf3784]

With 14g wire, 1 foot out, 1 foot back, thats about 0.005 ohms. Not much, but at 10 amperes, that amounts to 50mV drop all by itself. This is quite the interesting project to calibrate.

[@InssiAjaton]

Two things that i might do differently: First, I think I could get the fork connector cables folded over and just crimped that way. No soldering. Of course depends on, whether or not the forks actually take the folded cable end. The second thing is to make the highest current resistor as two in series and two of those in parallel. You would get 40 W resistor and avoid much of the thermal drift.

[@ZenwizardStudios]

I have some true current shunts at 10 and 20 amps. Seems my fluke meter was still quite accurate. Needed a little adjustment but not to much on the 10A range.

[@timgraham8975]

Wow that's Hot 650 Deg C aka 1202 Deg F.

[@timgraham8975]

Why did you not just do the adjustments using the 7510 in DC current mode as your transfer standard, at least to the 100-mA range?

[@ZenwizardStudios]

This is mainly because of the accuracy range of the meters. The accuracy ranges tend to be a little looser on the current range than the voltage range. DC volt will be the highest accuracy. The service manual specifies a 3458A and wants 0.001% resisters for the adjustment process. Though I should have used the 10 amp range on the 7150 rather than the fluke. However the fluke served to be quite accurate when checked with an appropriate current shunt in the lab not the resister.

[@wolfgangrichter6088]

Why is everybody using the less better Davespeak instead of English ?