[evlatests] VHF power level summary

[Barry Clark]

I think 8 or 10 dB above the P band is too high.  At that level, I 
think it can start contributing noise to P band.  I think 0 dB is
OK, but would say to boost anything negative.  So shoot for the range
0-7 dB.

My reasoning:  with an rms of order 6, the truncation noise in the 
A/D is about 18 dB below thermal, and evenly distributed across the 
band.  So if it is 18 dB below thermal at 4 Band, and P band is 10 dB
below 4, then it is only 8 dB below thermal at P band, which is starting
to pinch.