[evlatests] K-Band on Ant 18

[Robert Hayward]

Ken had indicated that he was seeing poor switched power from the K-Band 
on Antenna 18. Since this receiver was mounted long before the UX 
Converter arrived, it's output was probably not attenuated properly and 
was likely compressing the UX or Downconverter.

On Saturday during the Summer School tour, I did indeed find that the 
receiver output was unpadded so installed 8 dB attenuators on the 
receiver IF outputs. Alas, I had no time to investigate whether it made 
any difference (since Ant 18 does not have any TP detectors, I had 
planned to turn the Cals on and off while watching the change in 8-bit 
digitizer statistics).

I'll leave it to someone else to check if the SP has improved. In other 
words, play it again, Ken...