[Elecraft] KPA500 Z Bracket & Top Cover

[K6XX]

Chuck, 

Did you rotate the big transformer a little to get a better fit?

The toroid is wound with big wire, which overlaps. This creates the irregularities you see.
73 de  Bob, K6XX

Chuck - AE4CW <AE4CW at att.net> wrote:

>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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