See the attached...Why is the spectra below 5 & 8 hz elevated for Corner3 H & V on the CPS? V3 is a new CPS but it has been on the shelf for years now and while it has the copper braid in place, that braid is not zip tied at the sensor end (shouldn't impact things); both are attached to a feedthru that has recently been removed and replaced several times and the feedthru is currently not torqued down (should not impact the grounding); the Satellite box was moved around and its ground lug to the house ground was exercised as the ground cable had come loose... Need a little more attention here:
We'll try, 1) confirm ground is good on the rack put it back where it should be located under the Chamber, 2) Torque down the feedthru--like to do this after things look good but maybe it is to blame (I doubt it.)
Okay, managed to get a good signal from the Corner3 CPS on HAM6 but can't say I'm ready to put this to bed. See attached for the latest Spectra. The final solution was to have the Satellite crate on its side rather than the normal top side up.
I swapped one then both In-Air cables, disconnected grounds at the Satellite crate--had to put the crate on its side to do this (the screws are facing down) and this is when I got a good signal. Repeated this orientation thing I don't know how many times putting all the cables back, reconnecting the grounds, putting the feed-thru protector back on flopping the crate each time. No matter whether grounded, new cables, etc, the only way to get a steady spectra was to keep the crate on its side--hmmm I did not try both sides....
The crate orientation dependence suggests the cables connected are problematic or something in the crate itself is gravity sensitive. I could get no obvious issue to pop up as I manipulated the cables but maybe I did not manipulate enough. I'll bring in EE to see if they have any help for us.
Meanwhile, before tackling all this, I did all the things needed in-chamber first: 1) Got the zip-tie snug enough at the V3 sensor end: by unmounting the sensor assembly, I was able to apply just enough leverage to snug the tie around some slit kapton tubing supplied by Corey around the copper braid around the CPS cable. 2) Dressed the cabling for the Corner3 CPS cables on the NE side of Stage0 before heading into the 5-way Cross. 3) Changed the CU gasket on the 4.5" conflat and torqued it down.
Updating FRS 9477 but it remains open.
Also put a cable tie around the bundle of Accelerometer cables sitting in the spool, the idea being that given the impetus, cable might start to slip out of the spool and loop by loop drag the whole pile down and possibly sticking between Stage0 and the chamber shorting HEPI. The whole bundled pile being heavier will be less likely to move.