[hpsdr] Analog Vs. Switching power supply for OZY Janus...

[michael taylor]

On 6/11/07, k5nwa <k5nwa at sbcglobal.net> wrote:
>
> The problem I see with switchers is that although they could be made
> quiet, many do so at different degrees of success, so buying one is
> somewhat of a gamble unless someone else has had experience with the
> particular model that one is interested in. With an analog supply on
> the other hand, it's a non-issue.

Actually linear power actually can be an issue. First off, they are
inefficient, which means there will be a fair amount of wasted energy
ending up as heat, which if operated in an enclosed space or box
(Pandora) could affect oscillators and voltage stability.

The second is that linear voltage regulation is not necessarily a good
filter for ripple and transient spikes, which can be induced into the
power supply via the AC mains or DC supply leads.

Linear AN-101 discusses this, which I've already mentioned recently.
<http://lists.hpsdr.org/pipermail/hpsdr-hpsdr.org/2007-June/004864.html>

Lastly it seems odd to recommend usage of a 25 cent linear voltage
regulator (78xx series) with over at modern linear regulators such as
LM2940 or LP2954 which can improve line and load regulation by at
least one order of magnitude.

I have no preference of the choice of power supply type for HPSDR, but
I would prefer the decisions are made as informed choices, and
verified with experimentation & measurements.

-Michael, VE3TIX

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