[evlatests] P-band checkup

[Rick Perley]

     Frank generated a script today to do a quick check on P-band 
performance.  We observed 3C147, then a 'blank' region 10 degrees 
north.  I've taken a quick look, with the key results given below.
     Our goal is to generate a P-band 'stress test' (better to be called 
a 'check-up'), similar to what is run at the cassegrain bands,  to 
assist in diagnosing problems.

     Results:

     All antennas except ea02 (in the barn) were in the test.

     1) All antennas *except* ea08Y worked well.  The sensitivity of 
this polarization channel is less than half of the others.

     2) The usual 3.3 MHz ripple is seen in all bandpasses.  If (as 
likely) caused by a standing wave, the free-space separation is about 45 
meters.

     3) Antennas with more than 1 dB ripple (in power) are:   ea08Y (8 
dB !!),  and ea11 (X and Y) (just over 1 dB).

     4) Very large cross-polarizations are seen on some antennas.

          a) The worst (by far) are:  ea01, ea06, ea08, ea17, ea27. 
(ea01 is nearly 50% cross-polarized!!!).

          b) The best are:  ea04, ea07, ea10, ea11, ea12, ea13, ea14, 
ea18, ea21, ea23, ea24.  The cross-hand responses are all at the noise 
level (when observing 3C147).  This is what we should see.

     I don't know which antennas have had the P-band dipoles 'fixed' 
(here used in the original sense) -- I hope the list above includes all 
those so fixed.

     5) All antennas, except ea08Y, have, within ~10% or so, the same 
sensitivity in the central regions of P-band (SPWs 5 through 8).

     It would be useful to look at the antennas listed in 4(a), to see 
if their dipoles are oriented at large angles away from the quad legs.

     Rick