[evlatests] Ant. 13, IFs BD: ~60d phase jumps every 20 seconds at C, X, L bands

[Barry Clark]

This is almost certainly the heartbeat capture uncertaintly glitch we 
saw in the lab.  I am happy that things are now working well enough in 
the field that we notice it.  It could probably be cured by adding a foot 
of cable to the LVDS heartbeat cable.  Only worth doing if this L302 is 
in final form.

I've lost track of what the revision state of this L302 is.  The vaunted
spreadsheets in techdocs contain no useful information for L302s.


> AR603 data taken between July 12th and July 15th show an odd behavior
> for ant. 13, IFs BD (AIPS IF 2 RR & LL): frequent ~60 degree phase jumps 
> within a scan.