[Elecraft] Parallel Power Supplies

[Fred Townsend]

Was miniature 14-V power supply for travel
Rick I have renamed this thread because it has little to do with the
original thread.

In general it should be possible to parallel two power supplies. The
supposition theorem supports this idea however there are several practical
concerns that suggest this is not a good idea. 

First, even if the output voltages are identical, the output impedance of
the supplies may not be the same. The current will divide according to the
output impedance so you may not get the kind of current sharing you are
looking for. 

Second, some supplies have what is called foldover. This is the equivalent
of negative resistance and can cause the two power supplies to fight each
other. In extreme instances this can cause failures in either the load or
the supply. 

If you need short term surge I suggest a small gel cell or supercap across
the power supply output.

de Fred, AE6QL
 
-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Rick McClelland, AA5S
Sent: Wednesday, July 06, 2011 9:24 AM
To: Ralph Parker
Cc: Elecraft at mailman.qth.net
Subject: Re: [Elecraft] miniature 14-V power supply for travel

This brings a thought to mind, if I may briefly hijack this post.  Is it
acceptable to connect a Powerwerx 30 amp supply in parallel with a Gamma
HPS1-a supply in order to increase the current/surge capacity of the
Powerwerx supply?  This seems reasonable in theory but I don't know if the
two supplies might deliver slightly different voltages causing the regulator
on one to malfunction or fail.

Rick

On Tue, Jul 5, 2011 at 10:26 PM, Ralph Parker <ve7xf at dccnet.com> wrote:

> >Have you looked at the one from Powerwerx ?
> >
> http://www.powerwerx.com/batteries-chargers/powerwerx-30-amp-desktop-s
> witch
> ing-power-supply-powerpoles.html
>
> I bought one. Not exactly miniature, but smaller than my Samlex 1223.
> Runs the K3 + accessories easily. No noise issues (RF or acoustic) 
> that I could tell. I don't have a P3 (yet), but I'll betcha it'll fit 
> inside that case.
>
> Ralph, VE7XF
>
>
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--
Rick McClelland, AA5S
Fort Collins, CO
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