[evlatests] A most spectacular failure of 'set-and-remember'?

[Keith Morris]

ea18 and ea19 both show the same behavior in the T304-a: the input power 
and input attenuator were constant over the jump (at the nominal values) 
and the output attenuator and power changed, to their nominal values. 
This (and the AC-dependence) implies that the L302 was wrong, and became 
correct, since the output detector is post-conversion.

I can look into it further tomorrow.



On 1/13/2014 5:17 PM, Rick Perley wrote:
>
>      I'm calibrating 20 S-band databases, taken from November 2013
> through January 2014.    Five have been completed without any troubles
> (other than the usual satellite RFI).  But one is 'special':
>
>      For this database, the gains of all antennas jumped up, by a factor
> of ~ 2 to 10, at times roughly in the middle of the 90-minute run.  But ...
>
>      1) Only the A and C IFs jumped.
>      2) Each antenna jumped gain at a different time.
>      3) The new gain was in fact the correct one (judging from the
> calibrated gain values and PSum values).  Hence, *the initial power
> setup was too low by factors of a few*.  Somehow, this error was
> corrected in the middle of the run.
>
>      This SB was under program 13B-316.  The data were taken on 06 Dec
> 2013.
>
>      The time patterns of the jumps are curious:
>
>      1) Antennas 18, 19, 20, 22, 23 and 28 all jumped between 12:47 and
> 12:51 (IAT).  All jumps were 'clean' -- no more than one intermediate
> value is seen.
>      2) All other antennas jumped between 13:20 and 13:45.  Some of these
> jumps were not clean -- the system oscillated between the two states, or
> (in one case) hopped around three states, before stabilizing.
>
>      The initial scan for this run was many minutes long -- more than
> enough time for the system to find the 'right' level, and keep it.  But
> it didn't, and it didn't ...
>
>      Any ideas?
>
>
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