Unlike my ~2010 399MR in which I reset z0 every 3 months like clockwork!
Neal J Stolowich, PhD
NMR Facilities Manager,
and Senior Instructor
Department of Chemistry
University of Louisville
From: Ronald Crouch<mailto:roncrouch1_at_me.com>
Sent: ýSaturdayý, ýAugustý ý29ý, ý2015 ý5ý:ý24ý ýPM
To: Knut Mehr<mailto:knutmehr_at_me.com>
Cc: Kirk Manfredi<mailto:kirk.manfredi_at_uni.edu>, ammrl_at_ammrl.org<mailto:ammrl_at_ammrl.org>
I second Knut's observations. The Z0 DAC is about 0.045 Hz/unit 2H frequency. 15* 0.045 would be the 2H drift in a week. Multiple that by about 6.5 for 1H drift. Very stable magnet!
Ron
> On Aug 27, 2015, at 1:26 PM, Knut Mehr <knutmehr_at_me.com> wrote:
>
> Dear Kirk,
>
> this is not a problem at all.
> What you are observing is the underlying, and very slow, drift of the B0 field of your magnet.
> If I remember my Z0 calibrations correctly, you are seeing about 5 Hz/week of 1H frequency drift, which is a few orders of magnitude less than the commonly guaranteed drift for 400 MHz magnets (4Hz/hr, or even higher), but not entirely unheard of.
>
> Looks like you have an excellent magnet!
>
> - Knut
>
>> On Aug 26, 2015, at 2:42 PM, Kirk Manfredi <kirk.manfredi_at_uni.edu> wrote:
>>
>> We have a 2004 Inova 400 with a shielded 54 mm Oxford magnet. Last May we had an Agilent OneProbe installed and have been very happy with its performance. At the time of installation I logged the value of Z0 (on resonance) on a standard sample that we keep int the magnet when it is not in use (+1048). Since June of 2014 the Z0 value continually decreases. I is now at -192. It seems to change about 15 units a week. There are no other symptoms to the system (Unless I ran a long acquisition overnight?). I contacted Agilent about this problem some 6 months ago and they gave me the procedure to reset the spectrometer frequency but told me not to do it until there is a degradation in spectrometer performance.
>>
>> Any suggestions as to what this problem maybe and where it will lead?
>>
>> Kirk Manfredi
>> University of Northern Iowa
>
Received on Sat Aug 29 2015 - 12:03:02 MST