Doc,
I've said it before and I'll say it again: unless a power supply is
designated specifically for communications applications, assume that it is
NOT "clean enough" for communications usage. The unit in question is
almost surely a switcher, and if intended for commercial applications, it
will only meet FCC Part 15 Class A emission specs, which are several dB
worse (higher) than the Class B requirements for computers and digital
equipment used in the home. (Note that the seller is including shipping in
the $50 price - that tells me that the unit is light weight, virtually
guaranteeing it to be a switcher.)
For truly "clean" power, get a "hernia-maker" - meaning a linear power
supply, not a switcher. You only have to worry about 60 or 120 Hz hum and
ripple with those. If you don't want big iron like that, then stick with
the select group of switchers that are designed for communications
applications. Those units will exceed performance of FCC Class B equipment
by controlling both the radiated and conducted emissions. Yes, you will
pay more, but you get what you pay for.
If you watch closely, there are surplus equipment dealers (and people at
hamfests) who sell off big linear power supplies very cheaply. They were
the norm 20 or 30 years ago, and you can probably get one for under $50.
You'll want to find it locally, however, as these babies usually weigh 40
pounds or more when you start talking 50 amps (or greater) output current.
Unless malfunctioning, they usually deliver clean power to the loads.
73, Dale
WA9ENA
> [Original Message]
> From: doc@kd4e.com <doc@kd4e.com>
> To: RFI List <rfi@contesting.com>
> Date: 11/5/2010 9:35:04
> Subject: [RFI] Anyone know if this 12v ps is RFI-clean?
>
> Anyone know if this 12v ps is RFI-clean?
>
> "12 Volt 47 Amp Power supplies"
>
> See picture here:
> http://swap.qth.com/view_ad.php?counter=866425
>
> It looks like some sort of modified surplus server PS.
>
> I have asked the seller a couple of times but no clear
> answer yet. Does it look familiar to anyone?
>
> --
>
> Thanks! & 73, doc, KD4E
> http://KD4E.com
> Have an http://ultrafidian.com day
> Defend free speech or lose your freedom.
> I don't google I SEARCH! http://ixquick.com
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