[evlatests] L-Band status

[Rick Perley]

    At L-band, last night ...

    The 8 accepted antennas in service (i.e., excluding 16 and 21) all 
gave good fringes. 

    Antenna 21 fringes, but only barely.  The amplitude characteristics 
reported at X-band are reproduced exactly here.  So the troubles with 
the A and C IFs are global, and not specific to a band.  The sensitivity 
ratio between the AC and BD IFs reported at X-band are present at L-band 
also -- but the overall performance at L-band is much worse. 

    Otherwise, the standard problems, reported in the past, remain.  In 
brief:

    24C has a bad bandpass, and multiple amplitude states.  The data 
taken in the 'strongest' state have normal sensitivity.  All others 
represent lost information. 

    14C has the 150 degree phase jump (back and forth on a few seconds 
timescale). 

    Antenna 13 has the ramp-like gain on B and D, as shown at X-band.  
(I've not seen this before today). 

    A very few amplitude drops were noted in the fast sampled data (<< 
1%), and only on a few antennas (13, 24, 26) on the B D IFs only. 

    Sensitivities are pretty decent!  In particular, antennas 18, 23 and 
24 are very good -- at the top end of the distribution.  Antenna 13 is 
poor at 1465, but decent at 1385 MHz.  21 is, well, just awful.  All 
others are middling.