Project TBASErdn021120            Nov. 20, 2002

G. Watts and R. Norrod: Hunting for the cause of ~2% jumps in CM12-SF4
data taken in TRDN11_13_02B. First Galen removed CM12 and SF4 and checked
for loose connectors, and other obvious problems. Found two loose in CM12.
Put back in and we then setup with the DCR using IFRack noise source,
fiber links, Converter Rack, and detectors in SF modules. Setup same as
that described in TRDN11_13_02B.

Scans 1-5: 60s scans checking setup.
Changed to 300s scans.
Scans 6-7.

Swapped cables between CM and SF rack: CM12->SF3 and CM11->SF4.

Scans 8-10 indicate problem stayed with CM12. Changed to 60s scans.
Scans 11-56 wiggled various cables and knocked on modules. Found that MM 
fiber between SF4 and DCR was loose at SF4, but Galen had that off this
morning, so not the source of instability seen 11/13/02. Also found that
fiber and RF cable associated with Lasertron photodiode receiver used
in IF Ch #8 is EXTREMELY sensitive to mechanical pertubations. 

Scans 61-73 ran over lunch, and we saw a step in CM12-SF3 output again.

Sent OR6 output into CM12 A input instead of normal B input, and put 
CM11->SF3 and CM12->SF4 normal connection.

Scans 76-80: Saw step in CM12-SF4 output. From this and other tests, we
conclude that the problem is in CM12 somewhere after the input SPDT 
switch. Galen swapped out CM12 (SN12) with a spare module (SN17). 

Put OR6->CM12 B input normal connection.

Scans 81:101 - Just taking data. No steps in CM12-SF4 output. SF7-8 pair
shows long "warm-up" probably due to mechanical relaxation in Lasertron
fiber and/or RF output connections. Also, SF7-8 and SF1-2 pairs shows 
steps that may have been associated with antenna movements at the end
of maintenance day.

R. Norrod
11/20/2002