Tuesday, May 1, 2012

Tue., May 1st

Samad dropped off the batteries; I just need to figure out how these barrel-plug connectors on them are supposed to be used; [x] look that up. - Couldn't find one, and Samad said he couldn't either.  My main question is whether the first battery's output can be plugged into the second battery's charging input as a way of effectively connecting both batteries together in parallel.  If the first battery's level fell below the second's, the second would spill charge over into the first and fill it up to the point where they're equal again; amirite?

Also need to revise the PCB design for the new OCXO board.  OK, did that, and uploaded the new CAM files.  Order is ready to submit to Sunstone now.  Here's a layout image:

Layout of the new breakout board for the OCXO module.  Decreased line width on
output trace from 50 mils to 20 mils to minimize parasitic capacitance on this signal node.
Also added dimensions, a board descriptor, & added my initials to the vanity tag.
Other things to possibly do today:
  • [/] Solder down SMA connectors on FEDM board.
  • [/] Drill holes in platform for fastening down power cables.
  • [ ] Use circular saw to make a larger hole to run cables through - maybe do some more planning first though.
  • [ ] Make sure Ray understands the startup sequence. - He left for the day before we had time for this - we can do it tomorrow though.
OK, I soldered the connectors:

Right-angle SMA connectors soldered onto the appropriate pads of the FEDA module.
Slight discoloration around the pads is leftover cleaning fluid which I used to wash off the
excess solder flux.  If I knew where our can of air was, I would try drying it more quickly...
The FEDA (Front-End Data Acquisition) board needs to be re-tested, although perhaps I should wait for the cleaning fluid to dry completely first.  Idea:  Lay it on my household cooling fan (pointed straight up).

My little personal cooling fan doubles as an electronics dryer.
If I can get it looking dry before it's time for me to go today, I will reinstall it on the main platform and try running a system test.

Meanwhile, I drilled holes in the main platform to allow me to fasten down the ATX cable with cable ties (as opposed to the earlier electrical tape, which looked messy and was pulling away):

New ATX power cable arrangement.  Appropriately-sized holes were drilled in the main
platform at appropriate locations to allow me to pass large cable ties through the platform
which allows the ATX cable to be held down securely in a compact configuration.
The FEDA board is still not quite dry, so I don't think I'm going to be able to reassemble and retest the whole system today.  Guess I'll leave it drying overnight...

Meanwhile, did one more little thing:  Found some new top washers to hold down the cooling system bracket, to replace the larger ones that the guys had to cut down earlier (presumably to help them install/remove the cooling system around the board more easily).

New smaller washer to go under bolt head;
compare to the larger one which stuck out too
far and had to be cut back.  We'll still use the
large ones on the back side of the board, though.
Foo

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