[Elecraft] K3 power switching.

[Joe Subich, W4TV]

 > My question: is the power switch on the K3 mechanical?

No.  See the schematics available on the Elecraft Download
pages.  Power switching is controlled by a FET (Q2 on the
RF board).  There is a +13.8 "always on" line via a 1K
resistor for power control and unswitched +13.8V is supplied
to the KPAIO3/KPA3.

73,

   ... Joe, W4TV


On 2015-05-10 2:42 PM, G4GNX wrote:
> Following a mishap with a PSU, our local club’s K3 is in need of repair and I don’t want anything similar to happen to mine.
>
> The PSU is a linear device with a voltage control potentiometer and a meter. The operator had an issue with the PSU which was showing an output of 15 volts; the K3 was connected and working. He switched off the PSU to ‘exercise’ the potentiometer and unfortunately turned it back on with the K3 still connected and switched on. The reading was still 15 volts, so he touched the potentiometer again and the K3 started to emit smoke and died. At this time, we’re assuming that the PSU grossly over-volted.
>
> My question: is the power switch on the K3 mechanical? If it is, then my fears will not be realized because I ALWAYS turn on my PSU AND check the output voltage on its meter before turning on the K3.
>
> It will be interesting to find out what died in the K3. I hope it’s not too expensive.
>
> 73,
>
> Alan. G4GNX
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