[Elecraft] Switching Supplies

[Mike Penkas]

I  have 2 SEC1223's and no hash. I also have an Astron RS35 and RS50 linear 
supplies.  Sometimes the magnetic hum from them drives me crazy.  The little 
cork pads Astron puts in them to alleviate this
does not help much. I keep them under the closed console on the floor.
                      Mike  WA8EBM
----- Original Message ----- 
From: <williamsonr at pbtcomm.net>
To: <elecraft at mailman.qth.net>
Sent: Tuesday, July 08, 2008 6:28 AM
Subject: [Elecraft] Switching Supplies


> Pardon me if someone has already pointed this out (I have not followed the 
> entire thread)- my past experience with linear supplies reveals an all too 
> often failure mode of either shorted pass transistors or blown control 
> chips (LM-723).  In either case the output voltage from the supply can 
> rise to the unregulated DC filtered voltage (usually 20+ volts) and cook 
> anything attached.  A fast and effective crowbar, if designed correctly, 
> will clamp this voltage before it destroys your expensive equipment. With 
> switchers my experience has been that one or more of the switching FETs or 
> high speed diodes fail and the supply just dies (no output).  Which one 
> would you rather have connected to your brand new K3 if it failed?
>
> 73
> Rodger
> N4NRW
> counting down the day till the K3 arrival!
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