We have the same problems as you with dual C/H probeheads. I think
that in the new Bruker probehead the insert tubes have too thin walls: 6.0
mm o.d. and 5.4 mm i.d. When sample drops down with lift it slightly
oscillates, especially in WB magnets with a big sample spinner. All our three
inserts were broken at the top, higher the coil's position. To reinforce
this part of insert we have glued two turns of paper ca. 15 mm width by a
universal glue (I don't know western analogous one of our BF-2).
Another improvement of our dual and BB 5 mm probeheads is the
installation of shield for enhancement line shape. Such shields Bruker
installs into inverse probehead. I don't know what material Bruker uses. We
have glued thin aluminum tinfoil into 10 mm ring (1 and 1/4 turns) and
suited it on the outer insert tube. This shield prevents the excitation and
receiving signals from sample by proton coil legs. This idea was published
some years ago.
*********************
Dr. Yuri A. Strelenko
N.D.Zelinsky Institute of Organic Chemistry,
Leninsky prospect 47,
117913 Moscow B-334,
Russia
Fax (7-095) 135 5328
Tel (7-095) 135 9094
e-mail strel@ncc.free.net