Measurements of the 800 cals

14aug09

Measurements of the 800Mhz rcvr cals. The column with CurValues contains the current cal values.

date	measurement	in use
13aug09	cooled receiver with new cal cable installed 03jul09. Cals measured by ganesh with noise figure meter	cur values valid:03jul0-> installed 14aug09

13aug09 cal values

The new cooled 800 Mhz receiver was install on 28jun09. At this time the cal values was about 40 K. On 03jul09 the cal cables were changed (changing the amount of cal that was getting into the receiver. Dana remeasured the cal values on 13aug09 using the noise figure meter every 5 Mhz.

The plots show the new calvalues as well as the Tsys measurements using the old and new cal values (.ps) (.pdf):

Page 1: cal value [degK] vs frequency
Page 2: Tsys measurements done 30jul09 thru 13aug09 at 740 Mhz

top: Tsys using the old cal values. black is polA, red is polB
2nd: Tsys using the new cal values (13aug0)
bottom: Ratio TsysB/TsysA using the new cal value

Summary:

the cal value of polB is about 20 % higher than the cal value for polA
The tsys values using these cals shows a TsysValue for polB about 30% higher than polA
The rms noise for the dual position switching for a2488 showed a larger rms in polB than in polA
We need to compare the sefd for polA, polB to see if the Tsys is really different.

processing: x101/800/cals/14aug09/cmpcals.pro, chk800cals.pro

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