[evlatests] setting levels

[Travis Newton]

Currently the T304 attenuators are set at
8 dB (RF) and 16 dB(IF) to obtain a nominal
-37 dBm at the 1-2 GHz output.

The original plan was to have both attenuators
at 8 dB for a nominal level at -29 dBm on the 1-2 GHz output.

The new plan will be:
Setting both attenuators at 8 dB to obtain a -37 dBm
at the 1-2 GHz output
and
setting both attenuators at 8 dB to obtain a -25 dBm
at the 2-4 GHz output.

This will be achieved by removing some gain in the 1-2 path
in a new iteration of the T304 circuit boards.

This assumes the input to the T304 is nominally -38 dBm in the
7.5 - 12.5 GHz range.

Travis