3458A New Purchase - Question

[wn1fju]

I'm about to place an order for a 3458A at my workplace.  I've selected Option 002, the "high stability 4 ppm per year reference".  But I've
also tentatively selected Option OGC, the "precision calibration, intended for metrology use only."  Since budget concerns are not an issue,
I want the best I can get and I figured that Option 002 couldn't hurt.  But can someone actually explain to me what Option OGC is? 

Obviously, I can call Keysight and ask them, but I also want some second opinions.

Thanks.

[TiN]

I don't have actual information from keysight, but I'd expect OGC units are calibrated by Keysight Primary Lab, instead of just standard factory floor calibration.

Also if you plan to use meter for high-voltage AC purposes (standard unit is rated 750VRMS on AC only), you may want H01 option to extend range to 1000VRMS.

P.S. There is also HFL-option for 2 ppm/year reference . 73.

[wn1fju]

Thanks for the info.  I didn't see the -HFL 2 ppm option listed on Keysight's page.  Maybe it is by "special request only!"   Anyway, the
unit is already pushing over $12K USD and I'm starting to feel a little guilty about that, so I think the 4 ppm option will do OK.  We also
don't need to go higher than 750 VAC, so the standard AC is fine.

On the other hand, I'd bet you that the OGC calibration will probably add another month or two to the delivery time.  Ugh.

[TiN]

HFL option is listed in service orders for few K$, so perhaps you'd need talk to KS, yes. OGC should be about same ball-park for cost adder.
You could sent unit to Standards Lab calibration afterwards (which probably better idea, as brand new unit might need 6-8 months to fully stabilize first). AFAIK this calibration cost is about 2.7K$.

[dl1640]

HFL is only special calibration?

Once I falsely applied 1000Vrms onto 3458, a special beep was humming, then I realized it is a 750V model..better to order High AC option if you have money..

[martinr33]

One thing you might consider is grabbing a 732a instead of one of the high-dollar options.

These things are remarkably stable, and can help you sliminate any concerns about drift in your unit. Now, of course, you really need two of them to improve your ability to spot drift...

[wn1fju]

Thanks to Flinstone, TiN and others for all the useful information.  I'm inclined to stay with the 4 ppm option as I think that will be good enough for
my application.  I'll probably also spring for the precision calibration because just once in my life, I would like to say I know exactly what one volt is.
Well, at least with minimal uncertainty and for a few weeks until the thing drifts!

[metrologist]

Do we really expect a precision calibration to be more precise than whatever else they normally do?

[dl1640]

precision is made by design and proved by time and history. calibration is a prove of performance in one instance, thats why we need to calibrate on regular basis, in your case i think a standard cal before shipping is just enough..unless your application is very special and spec so tight..

i dont have an access to a 732 or the like, so we calibrate at KS our 3458-002, just standard cal.