TBASERDN040203

February 3, 2004

Q-band receiver in the Equipment Room, cold.  Using lab 83620 as LO1,
set at 9250MHz.  Connected IF of L2 and R2 to OR 2 and 4 respectively,
by coax.  These tests are after isolators installed between LNA and
polarizer in L2 and R2 channels.

L2 -> OR2 -> CM1 -> SF1 -> ACS J1 (bank 1, rcvr 1)
R2 -> OR4 -> CM5 -> SF5 -> ACS J2 (bank 1, rcvr 2)

T=120s, integration=10s.  ACS in one bank, two sampler mode.

Scans 2-12		  Rm Temp load on FE.

Scans 13-25		  LN2 load on FE.

Changed to L1, R1

L1 -> OR2 -> CM1 -> SF1 -> ACS J1 (bank 1, rcvr 1)
R1 -> OR4 -> CM5 -> SF5 -> ACS J2 (bank 1, rcvr 2)

Scans 26-45		LN2 load on FE.


Analysis:

Note: All the Ta/Tsys plots are multiplied by 100 so the vertical
scale is in percent.  Unless noted, the traces are offset by 0.5 for
clarity.

Plots qL2ovld040203.ps and qR2ovld040203.ps show the baselines for
scans 7:12 overlaid by scans 20:25.  Note that the Tsys decreased by
about a factor of about 2.6 with the LN2 load in place, see
qL2tsys040203.ps  The plots qL2s2_12.ps and qL2s13_25.ps give an idea
how the baselines varied throughout the two scan sequences.  The
traces are offset by 0.2.

Plots qL1ta040203.ps and qR1ta040203.ps show the baselines for scans
32:37 on channels L1 and R1 respectively.  File qL1R1tsys040203.ps
shows the Tsys/Tcal for each channel for scan 32.