[evlatests] Antenna 14 Birdies

[Charles Kutz]

All,

FE got a call about birdeis that were being observed in the X-Band on 
antenna 14. The concern was, that since we had just reinstalled the 
P-Band, the birdies had returned.

John and I made a quick trip back out to the antenna with a spectrum 
analyzer in tow.

The first thing that we noticed, was that the lights were left on in the 
vertex room. A call to Kerry Shores verified that he was still observing 
the birdies, so we turned off the lights and there was no change in his 
display, the birdies were still present.

We then looked at the X-Band and C-Band receiver outputs with the 
spectrum analyzer and saw only the bandpass of the respective receivers. 
There was some intermittent (very infrequent and low level) RFI in 
X-Band. The C-Band was only receiver noise. I.E. No birdies were present.

With the P-Band turned off, again there were no birdies in X or C. There 
was no change in the spectrum analyzer display at all. We also confirmed 
that Kerry was still observing the birdies.

We believe that the birdies are being generated downstream of the receivers.

Chuck Kutz