Check lbw polB cal cables.


    The polB cal value for lbw jumped on  23apr04 and again on   04dec05.   (by 20%).  In both cases the jump occurred for both diode 1 and diode 2 feeding polB. This shows that the problem was after the relay in the post amp chassis that selected diode 1 or diode 2 (i guess it could still be that relay). 

    On 06mar06 we tapped/wiggled the polB cable inside the post amp chassis as well as the  polB cables that goes from the post amp chassis to the dewar. While the cables were moved, the hcorcal 
was being turned on/off at a  1 second rate. The interim correlator was set for 4 25 Mhz bands centered at 1385, 1405,1425,a nd 1445 Mhz. The receiver was set for linear polarization's.

Data reduction.

    The computation was:

The data

    The plots show:
    the fractional change in the cal deflection while the cables were moved (.ps)  (.pdf):

What changed:

    processing: x101/060306/