Rodger, I assembled my K3 a couple of weeks ago (s/n 1217), and did not experience your problem. The three transistors clamped nicely against the (thicker) bottom cover using only the hardware specified in the instructions. As I recall, there are both 3/16" and 1/4" screws in the kit. You sure you've used the correct screws everywhere?
Took me about 10-11 hours to assemble my K3 (100W). I'm amazed you could do it only 4 hours! 73, Jim W8ZR > Hey gang, > > Just spent 4 hours assembling K3 s/n 1318 and all went well except for one > slight but potentially serious hardware problem. When installing the > bottom heat sink cover over the LPA I noticed that the required 4-40 x > 1/4" screws bottomed out in the standoffs under the TO-220 LPA transistors > before they would compress the cover to the transistors (and yes I can > measure screw lengths). This will leave a gap between the transistor and > the heatsink and not provide proper heat sinking! It is strange to note > that one of the Manual Errata changes was to point out that the heat sink > cover was "slightly" thicker than the other bottom cover. Wonder if this > part has changed? Any way, I added 3 #4 stainless steel flat washers > under the screw heads and that allows the screws to fully compress the > heat sink against the transistors. For a belts and suspenders fix I also > added a dab of heat sink compound to the transistors as well. I did not > check the screws coming from the top side of the LPA assy to see if the > factory may have used the wrong/longer screws > taking up extra standoff threads. A #4 split washer could have also been > left off of this top side screw and create the same issue or tol. stack up > of the parts? > > Any way HEADS UP! > > 73, > > Rodger > N4NRW > ft.com _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
