[evlatests] Antenna 18

[Rob Long]

We spent most of yesterday looking at ant 18.  The levels were checked 
and attenuators were added to the outputs of K-band; Q-band required no 
attenuators.  Switched power was present (on the Baseband overlay) but 
not very stable.  When we looked at the T-5, switched power was only 
apparent with many second averaging on the o'scope.  The dominant signal 
was a ~330 Hz oscillation that fluctuated in amplitude.

We checked the U/X converter for oscillating regulators, amps, etc.  and 
found nothing.  The IF outputs from the U/X and the T304 outputs looked 
good with the S/A.  I have some more tests to run today, but it seems 
that the likely culprit is still the U/X converter or something related 
as we do not see this problem in  L or X-band.

Rob