[Elecraft] KX1 Fire Sale

[w6fvi]

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

Paul T. Rubin wrote:

>Hello all:
>
> 
>
>I had disassembled my previously operational KX1 (SN854) in anticipation of
>adding the KXB3080 option.  However I realized that it would be some time
>before I could get around to it, and I felt like operating.  So I put it
>back together, powered it up, and released the smoke. Examination showed
>that a short section of V+ PCB trace just after the power switch had
>vaporized. PCB traces make excellent fusible links. I measured the
>resistance to ground from the far end of the trace.  It was 1025 Ohms.  By
>now I had a pretty good idea what was going on. I repaired the trace, and
>measured the same resistance at the power connector. So far so good.  I
>powered it up outside of the case and all is well.  Now I'm real sure what's
>going on.  I reassembled it into the case, and measured the resistance at
>the power connector; 0.4 Ohms. Q6 was shorted to the case. I backed off the
>screw for Q6 1/8 of a turn and the short goes away.  I examined the plastic
>spacer and it does not seem deformed.  The insulating pad also seems fine.
>I did not torque the screw to 20 foot pounds. I don't know what to do next.
>All suggestions appreciated.
>
> 
>
>Thanks,
>
> 
>
>Paul N8NOV
>
>Houston
>
> 
>
>_______________________________________________
>Elecraft mailing list
>Post to: Elecraft at 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
>
>
>  
>