[Elecraft] KPA500 Z Bracket & Top Cover

[Chuck - AE4CW]

Well, here what I discovered that is causing or contributing to the top cover
protrusion (at lease in my case):
1) My power transformer is not symmetrical.  It is thicker on the z-bracket
side and thinner on the left side.  When the nut is tightened, the metal
disk leans to the left causing the bolt to also lean to the left.  The head
of the bolt put a twisting moment on the bottom cover causing the left front
corner to be bent slightly down.  This then pulls the left side panel down
which now causes the front panel to also droop slightly on the left side. 
Now all of this is a matter 20-30 thousands of an inch, so it's certainly
not huge but enough to contribute to the protrusion.
2) The very top/front edge of the Z bracket protrudes several thousands of
an inch above the folded over portion that contains the screw bosses.  So,
tightening the front/middle cover screw actually causes the front cover to
be pushed up slightly at the edge.  I think this is a manufacturing defect.

Here's what I've done so far.
1) After loosening the transformer I straightened the slight bend in the
bottom cover by putting a shim under the left side panel and pressing down
with a blunt tool on the bottom cover just in front of the transformer.
2) I put some plastic shims under the metal disk on the thinner side to
allow the plate to remain level and the bolt perpendicular as the nut is
tightened.  There is still some distortion of the bottom cover when the nut
is tightened to 55 in-lbs.  I believe the extra plate on the bottom is
intended to remedy this, but there is still some distortion.

After all this there is still some protrusion but about 1/2 as much as
before...the total in the middle is about 30 thousands while the edges are
about 10 thousands.  So the middle is about 20 higher than it should be.

BTW, the z bracket by itself is not at fault (other than the slight defect
at the top/front.  It's actually about 8-10 thousands shorten in the front
than the rear.  So, bottom line, as best I can tell, the bottom cover
distortion caused by tightening the transformer bolt is the main culprit. 
Once again, this is NOT a big deal but just not quite up the the "fit and
finish" standard that Elecraft is well known for.  I'll give the folks in CA
a call next week to see what advice they have.
---
Chuck, AE4CW  

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