[evlatests] EVLA data of Jan 7th.

[Vivek Dhawan]

These tests were done to:

1. Look for scans with no fringes: seen by Rick, reputedly
in line mode. Many scans were done, in line mode. There were
times when fringes were weird: EVLA antennas did not correlate
with VLA with full(steady) amplitude, but sometimes correlated
between themselves. see item 4. This is certainly a problem, but
but it may not be the same as Rick's.

2. In line mode, (64chan in 6.25MHz, 2AC and 2BD modes) I was
also looking for the power-supply birdies at 700KHz. These were
present on some antennas/IFs, I'll send another email after a more
careful look.

3. To check bandpasses and sensitivity. Bandpasses looked normal,
but sensitivity will have to wait for clean data.

But I found:

4. A new problem: Dropouts in amplitude are seen in line mode, but not
always, and not exactly the same way each time. Things seemed to get
worse with time, as I cycled around bands and settings.

See the link for example plots.
http://www.aoc.nrao.edu/%7Evdhawan/EVLA-FEB7.PS

In time order,

X-band Continuum:  4 IF's worked well on 13, 14, 16.

L-band 2AC mode,  13, 14, 16 OK.

X  2AC: brief dropout about every 1 minute, 13, 14, 16.

K  2AC: 14, 16 OK. (13 no Rx)

X  2BD: 13, 14, 16 dropouts to VLA. 14-16 baseline looks OK(!)

K  2BD: no data 14 or 16.

L  2BD: like X 2BD

C  2AC: like X 2BD, but 14-16 not completely healthy.

Vivek.