[Elecraft] Protective zener diode failure

[Julian, G4ILO]

David Olean wrote:
> 
> I have a K3 and for the second time, the protective zener diode has
> shorted out for no apparent reason. The first time, I sent it back under
> warranty, but I was charged for the repair. It died again today with the
> voltage set at 12.4 vdc at the power supply, (an Acopian commercial rack
> mount unit)  In each case the radio was not being used. It was just
> sitting there with power applied. Does this happen often?  Anyone else
> suffer similar events? I had another K3 hooked up at the same time that
> did not die.  I am at a loss as to why it happens to the same rig. There
> were no thunderstorms in the area. The power supply still is delivering
> 12.4 volts.
> 
I don't think this happens often. I am running my K3 with 14.0V showing on
the internal display. Several people in the past have recommended running
the K3 on a higher voltage (below 15V) to get improved linearity from the
PA. So it is not a problem if the voltage remains within the recommended
limits.

I wonder if something is causing switching transients which are not being
filtered out by your supply? I would try using one of those protected
extension cables sold for use with computers on the input to your power
supply.

-----
Julian, G4ILO. K2 #392  K3 #222.
* G4ILO's Shack - http://www.g4ilo.com
* KComm - http://www.g4ilo.com/kcomm.html
* KTune - http://www.g4ilo.com/ktune.html

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