Finishing Cavity Soldering

I put some rubber on the tarmac this past week and made good progress:

  • I fixed all the open seams along the bottom:

    (Thanks to Randy for the suggestion about using a wet cloth to keep the heat from remelting the previously finished sides)
  • I then got help from my father to solder the top on (I am applying flux):

    There were two tricks, the first was to use a fairly thick but long rectangular piece of aluminum and wind it up inside where it pushed on the edges of both the top and bottom pieces to keep them round and line up the seams.  That aluminum piece won’t take solder and it is what is holding the top on in the picture above where, because of warping, my father is holding the seam closed.  The seam around the middle where I expected to have the most trouble is where I had the least, due to experience gained from the bottom.  Another trick was to use very little flux versus solder, such that I could tack the solder across the seam and then apply just enough heat to make it flatten out, then immediately blow to harden it in place.  The piece is held such that gravity pulls the solder down and around the seam.  Here is a shot from the raw footage after I have pulled out the aluminum ring:
  • I still have a couple hours of sanding to get all the rough edges smooth, both inside for smooth current flow and outside so it fits into the plastic enclosure.

    I bought really fine sand paper and the last sanding will be to buff and shine the inside to make sure no copper oxide is left over.

After sanding, the copper liner will be done and can be fitted into the plastic enclosure. (which from a few test fits, it is going to be nice and tight)

The list of things left to do is now a great deal shorter:

  • Get the tuning plate waterjet cut
  • Mount the probes
  • Mount the tuning mechanism
  • Bolt everything together

Then I will be going to the university to test the Q, hopefully somewhere close to the calculated maximum of 61K!  If there is a sufficiently high Q, then we can apply power and see if it moves (or melts, or does nothing).