[evlatests] Extended VLA L-band tuning

[Rick Perley]

    Last week, the L-band bandpass and bandstop filters were removed 
from two VLA antennas -- the identities of which were withheld from me 
-- in order to judge the sensitivities of the VLA without filter 
protection. 

    A test has been run to check the tuning capabilities of the VLA 
antennas, without the filters. 

    Determining the identities of the two modified antennas was 
completely trivial.  They are 5 and 10. 

    These two antennas give good strong fringes up to, and including 
1875 MHz (against EVLA antennas of course -- no other VLA antennas 
survive beyond 1737 MHz). 
    A strong birdie is seen at 1800.000 MHz on the VLA. 

    Neither antenna 5 nor 10 give fringes at 1900 MHz, but -- curiously 
-- antenna 5 does fringe at 1912 MHz.  Neither antenna fringes at any 
higher frequency. 

    All VLA antennas give fringes all the way down to 1150 MHz.  I 
didn't try tune any lower than this. 

    Details on sensitivities, etc., will follow later.  I have more 
tests to run yet today ...