I need to revise my initial statement. The switch is on the lock controller. It is labeled sync polarity. Here's a pic.
Sent from my iPhone
> On Jul 6, 2015, at 12:49 PM, Jacobsen, Neil E - (neil) <neil_at_email.arizona.edu> wrote:
>
> I sent a query a while ago about pumping the vacuum space of a donated Mercury-400. We are now at field and everything works fine EXCEPT:
>
> The deuterium lock will lock in perfectly with lockphase set to 0 or 360, but the lock signal is negative. The display goes down rather than up when it locks. The field is stable and you can do long acquisitions. If I set the lock phase to 180, it doesn’t lock and the lock frequency drifts away from zero frequency.
>
> The problem is that you can’t shim on the lock signal. The shim display (red thermometer) shows zero lock level because it can’t display the negative lock signal.
>
> I’ve tried many combinations of rebooting the host computer, restarting the acquisitons computer, power cycling the console, etc. I considered the possibility that I’m locked on a 2H sideband, but I get a 1H spectrum centered in the spectral window normally using the standard parameters and tof=0, and I can’t find any other 2H signal in the complete range of Z0 (-2048 to 2048).
>
> I have to assume that some component in the lock system has gone bad during the long (4 year) sleep of the console, but I keep wondering (since it’s a Varian) if it might be a software issue. I would appreciate any suggestions.
>
> Neil
Received on Mon Jul 06 2015 - 09:14:58 MST