Dear Colleagues,
Back in the late '90s, the original Varian (UNITY and UNITY-INOVA) narrow-bore CPMAS probes came with a basic set of fiberglass tuning-range sticks that either had ATC-Chip capacitors or inductor-coils with varying numbers of turns. These tuning elements are soldered to a small PCB "paddle" at the end of the fiberglass stick, and could be pushed-in from the bottom. As an option, Varian had an "extended tuning kit" that was available, which included many extra sticks with more capacitance or inductance values. The basic CPMAS probe came for just 4 basic X nuclei, including no-stick for 13C. (Note: These were the original Red solids probes that used the Jakobsen spinning module made of a block of Zirconia, long before Varian purchased Otsuka-Chemagnetics and switched to Chemagnetics probes/spinners.)
My probe is now equipped with a wonderful David Lewis spinning module from Revolution NMR, but I still only have 4 tuning-range sticks; therefore, I have to de-solder/re-solder tuning elements to the PCB-board when I want to change to more uncommon frequencies, and some of the mid-frequency nuclei require inductor-sticks employing 20, 30, even 50+ turns on the inductor coil. I make my own inductors and capacitor arrays, but it's not easy to make a good 50-turn inductor coil that will withstand multiple de-solderings and re-solderings.
So, my hope is that there might be somebody out there with one of these old red probes who also happens to have the "extended tuning kit" with 17 additional tuning-range sticks, and also might be willing to part with these tuning sticks (I know, ... crazy, right?)
If I had several sticks, I could make one for every nucleus that I observe, label it per nucleus, and be able accommodate users who say "oh, can I have 11B as well" after asking to do 13C & 31P CPMAS. Last option is to fabricate the entire assemblies, but our machine shop rates might prohibit that.
If my description of the exact probe and tuning sticks isn't clear, feel free to email me and I'll take a picture or something.
Thanks in advance to anyone who even takes time to look around for me, I know everyone is very busy.
Cheers,
-Rich Shoemaker
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Richard K. Shoemaker, Ph.D.,
Research Professor & Director, NMR Spectroscopy Facility
University of Colorado at Boulder
Phone: (303) 492-7062 Fax: (303) 492-5894
E-Mail: Richard.Shoemaker_at_Colorado.edu<mailto:Richard.Shoemaker_at_Colorado.edu>
Web: http://chemnmr.colorado.edu/rshoe
Received on Wed Sep 10 2014 - 14:12:13 MST