Spectrometer A is our high resolution 360 MHz wide bore system which is used primarily for multinuclear and in-vivo NMR studies. During the past year we have made several improvements to the spectrometer. We have installed vibration damping legs to the magnet to eliminate vibration sidebands. The old transmitter electronics has been replaced with two channels of our new design. We can now perform experiments with full control of the transmitter frequency, phase, and amplitude. All of the high resolution and solid state spectrometers in the facility with the exception of the EPR spectrometer now use the new transmitter design. We have also replaced the receiver electronics with the new design which had just been designed at the end of last year. The new design has a 16 bit analog to digital converter and a novel computer controlled method of correcting for amplitude and phase errors between the real and imaginary channels. The old design used pc board relays to control rf gain and the filter cutoff frequency. The new design uses only solid state components. It has a better gain distribution than the previous design, which permits better S/N performance at lower gains. With the exception of the DNP spectrometer, all of our spectrometers now use the new hardware. The solid state spectrometers, however, continue to use commercial digital storage oscilloscopes for signal digitization. The new averager which was available only on Spectrometer E last year has now been added to all of our high resolution spectrometers. The averager is double buffered and can transfer the data from one 2D or 3D slice to the computer while the next is being acquired. This has greatly improved our throughput for 3D experiments. We have constructed enough new averagers for all of the solid state spectrometers, but have not yet installed them.
Showing the most recent 10 out of 12 publications
