Re: [AMMRL] Tuning issue with VNMRJ3.2 on Agilent DD2

From: Spin-Doc <bert.heise_at_spin-doc.net>
Date: Fri, 6 Feb 2026 14:30:48 -0600
Hi,

This usually might be either

a) a corrupt tuning persistence file
- try to delete the local persistence directory vnmrsys/tune/PROBENAME

b) the mechanics/torque limiters may have slipped a bit, making the system think the end stop is elsewhere 
- power cycle the Protune motor box and try to tune again.

c) a slight change in the RF path, possibly from a connection or filter (visible usually if the rest of the wobble range is very bumpy instead of flat)
- try to re-do (as vnmr1) the highband tune calibration (open/50 Ohm/short plug), also make sure only one each high- and lowband calibration file is found in /vnmr/tune/tunecal_PROBENAME

Best regards
Bert

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Am 06.02.2026 um 11:29 schrieb Emily Crull via groups.io <emil= y.crull=mail.wvu.edu_at_groups.io>:


Hi all,
 
We are having an issue with our 1H channel, which also does 19F. We= 9;ve determined that it is either a probe issue (besides the motors, which are moving smoothly) or a program issue.
 
Rather than find the dip for the 19F, ProTune skips right over it in the tune window. The dip appears, but it is not being detected as a dip, so the tune setting goes straight to the lowest point, which is not where the dip is located. Since the program can't find the dip when sweeping the tune, it also doesn't adjust the match to try and find it. It also sweeps the whole window, not just a 10MHz range of where the dip should be. This happens with coarse, medium, and fine settings, and always results in the tune failing. 
 
The X channel is operating fine and tuning perfectly to the bottom of the dip.
 
We can manually tune on this instrument, but that defeats the purpose of having an autotune probe.
 
Has anyone encountered this glitch before and if so, how did you fix it? 
 
Best,
Emily Crull
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Received on Fri Feb 06 2026 - 12:33:09 MST

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