[evlatests] More on square-wave and sinusoidal phases ...

[Rick Perley]

    The tests last night were made in two different modes:

    a) Continuum, with 50 MHz BW
    b) Line, mode '4', with 12.5 MHz BW. 

    I reported on the very curious phases seen in the continuum 
observations in antennas 19, 21, and 24.  Briefly:

    Antenna 19 has a 10-second regular square wave pattern, on IFs B and 
C only.   The size of the steps are independent of frequency.   The sign 
of the phase change is opposite between B and C. 
    Antenna 21 has a slow (period ~1 minute) sinusoidal phase, on IFs A 
and B.  (IFs C and D were not working, so statement can be made).  The 
amplitude of the pattern is proportional to frequency. 
    Antenna 24 has an occasional (~1/minute) phase offset, duration 10 
seconds, on IFs B and D only. 

    Some interesting differences were seen in the line data, taken at 
the same frequencies, but with 12.5 MHz BW:

    Antenna 19 was good on all four IFs at X-band.  The square wave was 
not present!
    Antenna 21's sinusoid was present. 
    Antenna 24's occasional phase jumps on B and D were present at L and 
X, but absent at C and K.  But even when present, the repetition rate 
was much lower than at 50 MHz BW -- about once per 5 minutes.