I'll add to Brian's comments that it does not always require a burr to produce the short.
In some KX1s either the head of the screw is a tiny bit smaller or the hole is a tiny bit larger, allowing the beveled screw head to reach through the hole in the cover and thermal-conducting pad and touch the metal tab on the transistor, causing a short. I fixed mine long, long ago by adding a second thermal-conducting pad. Still, I'm very careful to check for a short whenever I reassemble it. But in dozens of disassembly/reassembly operations it's never been shorted. Others, with slightly smaller case holes or screws with a slightly bigger head never had the problem. They were unable to create a short, even when trying. The nylon screw is the really foolproof solution. That's why they are supplied with all current KX1s. Ron AC7AC -----Original Message----- Hi, Paul! Sounds like a tiny metal burr is shorting the case of Q6 to ground. These are almost always at the screw hole. Check the following: 1. Make sure the screw itself is plastic; Elecraft will send you a new one free if it isn't. 2. Pull off the insulated pad and use an Xacto knife from the inside of the cover to "circle" (swirl around at a 45 deg angle) the Q6 mounting hole and remove any burrs. 3. Using fine sandpaper, sand the area inside the case that the insulated pad covers to ensure it is perfectly flat, especially around the screw hole. Replace the insulated pad and reassemble. Very smart of you to use an ohm meter to alert you of potential smoke inhalation during power-up. Brian - W6FVI _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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