DATE |
MAINTENANCE |
Sep 2006 |
refrigerator failed (stage3 at xx K); removed from C11, shipped to Berkeley |
Oct 2006 |
found jammed clothespin on inlet valve; replaced valve plate baked displacers new Scotch yoke bushings and Kap-Seal new stage3 seal installed thermal stabilizers on stage3 and on mixer blocks cooldown.01nov06 shows 2nd stage problem |
02 Nov 2006 |
replaced stage1 and stage2 seals; phenolic has slight chip just above stage2 seal cooldown.03nov06 at 30 rpm, mixerB is at 3.2 to 3.35 K |
08 Nov 2006 |
dewar installed on C13 |
22 Apr 2008 |
dewar removed from C13, brought back to Berkeley
to swap in HIA mixer; found about half a teaspoon of water on displacers; vacuum
baked displacers, replaced stage 1,2,3 seals; removed sight glass and wiped oil
off inside, but did not fiddle with Scotch yoke bearings |
29 Apr 2008 |
tested HIA mixer; refrig running at 56 / 13.5 / 3.1 / 3.4 / 3.2 K
|
07 May 2008 |
dewar installed on C7 |
05 Aug 2009 |
dewar removed from C7; wiring problem to 1mm mixer |
Aug 2009 |
removed "good" motor/displacer assembly 5746, installed
in dewar7, cyl 5093, which now cools well
(52 / 11.8 / 3.0 K); unfortunately "bad" motor/displacer 5093 works poorly in dewar5,
bottoms at (53 / 13.8 / 4.2 K) in test [917] |
Sep 2009 |
[918] bottoms at (52 / 19.4 /4.2) after swapping in spare 2nd stage from OVRO [919] bottoms at (56 / 18.9 / 4.2) with another spare 2nd stage [920] bottoms at (63 / 13.6 / 4.0) with original 2nd stage, new 2nd stage seal [942] retest Apr 2010 bottoms at (59 / 13.3 / 3.9) |
16 Apr 2010 |
removed 69 g Er3Ni spheres from stage3 displacer (#30),
replaced with 67 g HoCu2 spheres; [943] bottoms at (60.1 / 13.2 / 3.30); stage3 runs at 4.03 K with 50 mW load, 4.63 K with 100 mW load |