cylinder 6418, motor 5578; 3rd stage displacer has brass tip
29 Jul 2005
installed dewar10 on C8
8 Oct 2005
cold head ratcheting, on slow or fast speed; motor blows fuses on compressor box; later, Mark changed motors
6 Feb 2006
replaced motor with another spare motor from Curt;
decided that displacer was not able to center itself properly, which put too much force on the motor;
cleaned displacers and cylinder but did not replace seals;
polished displacer linkage sleeve to encourage displacer to center itself in the cylinder
24 Feb 2006
lab tests after rotating 3mm pol; 1mm mixer bias shorted out
06 Mar 2006
installed dewar10 on C12
05 Feb 2007
removed dewar10 fron C12; WBA13 gate bias seemed to be shorted; refrig running a bit warm (stage3 ~ 4K)
15 Feb 2007
ultrasonically cleaned displacers in isopropyl alcohol, then vacuum baked
3rd stage displacer badly scuffed by seal; brass section also scraped near tip; polished most of the scratches off with sandpaper in the lathe;
Bal-Seal jacket completely worn through on one side, spring wire worn - explaining scratches in displacer!
replaced 1st, 2nd, 3rd stage seals, but did not touch scotch yoke bushings or valves
03 Mar 2008
installed on C14 at Cedar Flat
28 Apr 2010
removed from C14 at Cedar Flat
24 May 2010
cleaned displacers and cylinder, replaced stage3 seal - worn through to the spring in 2 areas; did not change stage1 or stage2 seals, or replace bushings or Kap-Seal; 2nd stage seal thickness is 0.057; measurements of stage3 displacer: SS seal rubbing area, 0.4961; plastic, 0.4980-0.4990; brass tip, 0.4955-0.4975