[evlatests] More on 'The Phenomenon'

[Michael Rupen]

> ...It's probable that 
> the lines won't move much with frequency, so we should be able to alert 
> people to where they are, so frequencies of interest can avoid these 'noisy' 
> zones.

This will be a bit complicated in practice.

* The resonance phenomenon does shift with temperature.

* We do not know much about the long-timescale stability of the resonance
   frequency.

* We are not seeing the resonance directly, but rather an aliased version
   coming into the 2 GHz band of the sampler.  Thus the equivalent
   sky frequency will depend on (at least) the LO tuning.

               -- Michael