[evlatests] RFI environment changes @ VLA:

[Dan Mertely3]

I have a question for anyone doing EVLA hardware
mods:  The very bad L-band RFI I have been seeing
on our monitor plots suddenly disappeared after
last Tuesday, February 13th.  It showed up as
usual from around 9 PM on the evening of the 12th,
lasting until (as usual) around 10 AM on Tuesday the 13th,
but then never showed-up the night of the 13th,
or anytime since then.  Did anyone change-out
some potentially RFI generating hardware in
one of the EVLA antennas on that day, hardware that
had been in-place since early October 2005?  (Has
any EVLA hardware been in-place for that long,
undisturbed?)  Was an EVLA antenna moved out,
away from pad W8 on that day?  If so, which one?

Prior to last Tuesday, since early October, I was seeing a lot
of strong RFI in L-band at (around) 1405, 1470, 1475,
1540, & 1570 MHz.  The stuff would go on, mainly
at night & morning (intermittently), and hop around
in frequency by about 5 MHz.

I never was able to get a directional fix on it
because our portable spectrum analyzers had such
poor sensitivity compared to the output of the
cryo L-band on ant 06 that our monitor is connected
to. (+ it was on mainly at night, was intermittent,
and moved around in frequency)

Any ideas?

-Mert