[evlatests] Extended VLA L-band tuning

[Dan Mertely]

Yes, VLA antennas 05 & 10 were the antennas I
removed the filters from, you diviner of astronomical
esoterica!  I would be interested in knowing (at
someone's leisure) whether there is any indication
that the strong DME & ATCRBS signals below 1210 MHz
show any non-linear effects.  -Mert


Rick Perley wrote:
>     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 ...
> 
> 
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