[evlatests] 3-bit sampler survey

[Vivek Dhawan]

The 3-bit samplers now number 120. The ~15 problem children are called
out in two lists: the first with repeat offenders and the second with
fresh problems (either newly installed samplers, or older ones which
have gone awry somehow.)

1. These samplers are notably worse than the rest, 50% or more noise, and
    their properties repeat from last month's list.

10C1 has bad notches in the bandpass caused by the DTS somehow mis-set.
10A1 used to have the same, but is now good.
13A2 higher noise
16B1B2 higher noise
18A2 higher noise, dip in bandpass (not DTS related)
22A1A2 higher noise
22D1D2 - see Ken's note.
25A2 higher noise - See ken's note.

2. New (problem seen in data from yesterday, not before)

5D1 higher noise
7A1 now good. 7B1D1 no fringes, cause unknown.
19C2 factor 2 higher noise - see Ken's note.




Ken Sowinski wrote:
> Vivek and I spent an hour looking at three-bit samplers for obvious
> problems.  Herewith the short list.  These account for some of the
> problems that have been reported by Vivek, but by no means all.
> 
> ea19C2 has a 2.5 bin DC offset when the sample multiplier is set
> to the canonical 32.  Setting it to 8 produces a nicer looking
> state count histogram, but that should not be necessary  We suggest
> that something is wrong with this sampler.
> 
> ea22-t304-D output cables are swapped n the way to samplers.
> What appears in the correlater as D1 is really D2 and vice versa.
> 
> ea25-d302 and d304 default to a sampler multiplier of 64 rather
> than 32.  I will lookup Mike's explanation of how to remedy this
> and take care of it.
> 
> 
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