> I can tell you that Telex takes an interesting approach with their
> BTR-800 wireless intercom base station: its a commercial line-lump
> type switch mode power supply (24Vdc 2.5A) butted right up to the
> rear panel of the 1RU enclosure.  Its held in place with a 4-sided
> metal box (front, sides, top) that totally encloses the plastic
> case.  The front of the box has a slit that the DC output cord exits from.
>
> Its pretty tidy - the power supply has the standard IEC power
> connector that lines up with a matching hole in the rear of the 1RU
> enclosure.  The DC output cable has a large Ferrite bead, then
> solders to the main PCB.  The system power switch is in series with
> the DC output of the supply.
>
> I'm guessing that Telex chose to enclose the whole power supply in
> metal to reduce RF interference within their enclosure (I did mention
> this is a wireless intercom system).
>
> dwayne

That is pretty neat. I wonder if they surrounded it by metal because it
perhaps has no mounting holes. All you can do is trap the thing in place.
I also wonder if enclosing it interferes with the convection cooling,
perhaps raising UL issues. Finally, I wonder if cutting the DC cable and
connector off to make it short enough and have it soldered directly to the
board would be an unauthorized modification voiding the UL listing of the
supply itself. I assume the Telex box is UL listed. Wouldn't it be nice if
the AC inlet had a couple screw holes that allowed it to be screwed to the
rear panel? Of course, someone would put in screws that were too long and
mess things up.

Thanks for the info!

Harold

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