[evlatests] L30x Comb generator RFI.

[Vivek Dhawan]

I got a spectrum of the (unshielded) L300 comb generator measured by
Colton Dunlap and Mertely, 1-18GHz. I picked off some strong lines and
tried to find them on the VLA system. 1408 and 22272 were seen.
8192 was missed in the first attempt but WAS seen subsequently -
(my notes were sketchy, I have reloaded the archive data to
make sure). 8448 was weak on 2 occasions.

4608 was very strong on the lab spectrum but not seen on the VLA.

It was not clear if these birdies were really in the RF band, or leaking 
in somewhere in the IF.

When this was reported back in January, I was told:

1. that the comb generators were different on production antennas
compared to 14 and 16 (what flavour is 13?).

2. And that Hollis had a design to shield the comb generators but it
had not yet been implimented.

I intend to run these tests again as soon as its deemed useful.

Vivek.