[evlatests] S&R failure statistics

[Rick Perley]

     Ken asked if the 'set and remember' (= S&R) failures repeated from 
one day to another, and how these failures were distributed over bands 
and IFs.

     I've done the numbers, from my recent three science runs, all using 
X through Q bands.

     1) Distribution over bands/IFs.

             Although these failures (defined here as the power to the 
sampler low by a factor of two or more) occur at all bands and IFs, they 
are uncommon *except* in the 10 -- 12 GHz IF band. (Uncommon is defined 
as five failures or less out of the 27 antennas).  In the 10-12 GHz 
band, more than half the antennas fail.


     2) Distribution over time.

             The statistics failures are the same over time for the thee 
runs.  However, it is not true that the same antennas fail each time.  
Indeed, there is little to no repeatibility in which antennas fail to 
have their powers set.

     One other point -- Xband Hi (10 -- 12 GHz) not only fails far more 
frequently than any other, but the severity of the failure is also very 
much higher.  I have an example of an antenna whose power was low by 
nearly a factor of 10,000!