[Elecraft] Protective zener diode failure

[Bob Allen]

Dave,
Does the PS have a high voltage protective "crowbar" circuit?
I have never examined the reactive speed of the circuit  (I have them in 
Astron linear supplies I own)  so I don't have any idea if they would be 
fast enough to protect you but you would think  it would trip  on 
overvoltage  if you had a transient high enough to blow the diode.
On the Astron supplies once this trips it stays at O volts output until 
the power is recycled. This circuit is troublesome on some Astron 
supplies due to tripping for no reason, there are fixes for it.
Bob
KB1FRW

David Olean wrote:
> Hello Matt and Julian,
> It is D-28, the big fat zener.  I had two K3's running off the same supply. 
> I have not had any failures of this type with other gear in the past. I 
> think I will put some logging software on the output of the supply and look 
> at the results. Both failures happened when I was not there to see it.. I 
> have to set the logging program sample rate fast enough to see transients 
> though. The recording might look like several miles long on my screen!!
>     Acopian makes commercial supplies. This one is linear with a number of 
> pass transistors. It seems to be working just fine. Stable wiith great 
> regulation. However my nose has wrinkled too. I suspect an internal weird 
> problem with the PS.  I will use a DATAQ data logger on it, so I can watch 
> the ouitput on the computer at my leisure. I better substitute a big 
> resistor rather than the K3 this time.
>
> Dave K1WHS
>
>
>