[evlatests] high level 3-bit sampler summary

[Ken Sowinski]

Using testing of the new configuration mapper as an excuse I ran
several 3-bit sampler tests this afternoon and tried to have a careful
look at what each sampler was doing.  Here is the short summary.

Hittite samplers.
In general these seem to require less drive, or have more internal
gain, than the teledyne-based modules.  Even with the output
attenuators set to 31 dB these samplers are being overdriven by
a lot.  The modules in ea03 and ea16 are worst; the one in ea25 is
almost acceptable.  To test how these samplers work when driven
correctly we can put together a test script which sets the T304
input attenuators to provide a few dB less power.

Teledyne samplers
There is only one which is easily seen to be grossly wrong,  The
sampler for ea19/C2 (in module D303) claims to have a DC offset
of 3.5 bins and doesn't work well at all.  The remainder have no
problems that can be seen at this cursory level of inspection.