[evlatests] phase jumps

[Jim Ulvestad]

When there is a jump, do all the antennas that jump
move by the same amount?  Or do different antennas
jump by 35, 50, or 90 degrees at the same time?

Jim

> In earlier reports Rick has pointed out phase jumps in VLA antennas
> occurring on frequency changes.  Last week I established that these
> jumps do no occur when just the flukes are changed.  A further test
> run last night did show the usual phase jumps when changing L6.
>
> This observation was X-band, at four different L6 values for one
> minute each.  This set of four was then repeated 14 times, for a
> total of one hour.
>
> The signature is the same: the phase jumps to a completely differ-
> ent value in one scan, then jumps back to its original value in
> the next scan.  The phase jumps can be of any magnitude: examples
> are 35, 50, and 90 degrees.  Some antennas are worse than others
> (8 and 12), others are largely free of this effect (7, 9, 10, 15,
> 22, 24, 25).
>
> Gustaaf
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