[evlatests] A few notes on PDif and Switch problems

[Rick Perley]

     A couple of clarifications, arising from the meeting this afternoon:

     1) The loss in gain due to the T303 switch issues is far more than 
a few percent.  It's typically 10%, often 20% (in power).

     2) I had a thought at looking for Q-band PDif compression from my 
calibrator data -- plotting PDif vs elevation should show this. But it 
is significantly confused by the temporal gain variation caused by the 
ambient temperature change.  Certainly, the PDif problem is generally 
less than the temporal gain change (10 -- 15%).  Plotting PDif vs. 
elevation over a limited time range (such as what Vivek does) where the 
temperature-induced gain change is small might work.