[evlatests] 4band, interference and ea14

[Frazer Owen]

     We made a successful test of the the new 4band MJP dipoles using 
antennas 12, 14, and 19. 14 is important for interference tests because 
it has the new ACU.  The autocorrelations on 12 and 19 show the 5MHz 
clock comb that is thought to come from the old ACU. 60 MHz is 
particularly strong and variable for test to test. The autocorrelations 
for antenna 14 do not show the 5MHz comb. This seems to confirm that 
that the 5 MHz comb is from the old ACU

      Antenna 14 also does not show interference at 64MHz, which I 
understood was a possible frequency from the new ACU. It does show a 
fairly strong spike at 55.25, much stronger than any else in the 54-86 
MHz band. The very narrow spike is clearly different from the 55MHz 
spike on 12 and 19, which is part of the 5MHz comb. 12 and 19 don't show 
a spike at 55.25.

     Interestingly the 5MHz comb frequencies correlate on baselines to 
14 (as they do on 12-19). Since the 5MHz clock is supposed to be 
incoherent from antenna to antenna, there must be a general source of 
the comb frequencies, especially 60MHz, which is being broadcast around 
the site. Could this be one very bad antenna ?

---Frazer