[evlatests] X-band Lunar Compression

[Rick Perley]

    The moon seems to provide 160 -- 200 K to the system temperature at 
X-band -- which multiplies the total system temperature over cold sky by 
about a factor of 6. 

    The apparent PDif compression*100 (ratio of switched power on moon 
to that on cold sky, multiplied by 100) is given below. 

    Special Problems:

    1) ea02 has zero-mean PDif on all IFs.  Only noise is seen in the 
difference.
    2) ea16A has a ratio of -0.59:   the cold sky value of PDif = 90 
millicounts.  The moon value of PDif = -50 millicounts.  This is unique 
behavior -- I've not seen a consistent negative PDif on any antenna, on 
any IF, at any band, on any other test I've ever done. 
    3) antennas 8, 12, 15, 20 and 28 are the 'old-style' receivers.  For 
these there is no PDif on the BD side -- the entries are marked with 
'x'.  Note that for these antennas, in the 'AC' IFs, there is virtually 
no PDif compression.  This behavior has been noted before in other 
tests.  Since the 'old style' X-band receivers provide much less power 
to the T304 than the new style, this lack of compression for them is 
strong evidence that the problem (for this band, at least) arises in the 
T304. 

Ant.      A     B     C     D
------------------------------------
01        91    85    93    78
02       zero-mean PDif
03      100     x    100    x
04        81    82    81    89
05        81    80    86    65
06        88    72    85    86
07        63    52    86    77
08        99      x   101   x
09                   out
10        91    72    92    86
11        91    82    84   100
12       100     x   100   x
13        95    85    88    69
14        94    84    91    79
15       101     x    98     x
16        ??    56    48    71
17        84    75    79    68
18        85    61    89    77
19        96    78    87    87
20       104     x   102    x
21        95    89    98    91
22        79    88    81    80
23        89    91    85    81
24        83    80    89    64
25      100   100   99    92
26        83    73    83    71
27        93    88   100  100
28       102     x   100    x
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