[Elecraft] RS 22-507 Power Supply

[David Cutter]

It sounds like a malfunction in the start-up circuit.  How is the psu 
switched off?   My guess is it is not an isolating switch on the supply 
input, but some low power circuit that sends a signal to the start-up 
circuit.  This is not an area to be tackled lightly, as it is at mains 
potential.  Over here that can be lethal, but still be careful how you 
investigate.

David
G3UNA

----- Original Message ----- 
From: "Augie Hansen" <augie.hansen at comcast.net>
To: "Bob Tellefsen" <n6wg at comcast.net>
Cc: "Elecraft Reflector" <Elecraft at mailman.qth.net>
Sent: Tuesday, March 27, 2007 10:06 PM
Subject: Re: [Elecraft] RS 22-507 Power Supply


> Bob Tellefsen wrote:
>> Gus
>> I remember reading somewhere that switching supplies
>> require some minimum load to be stable.  You could
>> try putting a small resistive load, maybe 50 mA, on the
>> P/S and see if it calms down.
>> Good luck and 73
>> Bob N6WG
>
> Hi Bob,
>
> The loads on the supply are greater than 200mA in each of the operating 
> cases I described. My concern is not with output stability under load. 
> Rather, I want the supply to really be off when I turn off its power 
> switch. It apparently isn't, producing those unexpected pulses.
>
> I was alerted to this problem when my computer kept displaying messages 
> about a network connection being connected and disconnected periodically. 
> The PIC MCU project I'm working on has a Lantronix XPort IP-to-serial 
> interface unit on it, and the short bursts of power were causing it to 
> wake up and respond over the network.
>
> Thanks,
> Gus
>
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