[RFI] DC Power supplies

Jim Brown jim at audiosystemsgroup.com
Tue May 10 13:22:54 EDT 2016

On Wed,5/4/2016 2:59 PM, Doug Powell wrote:
> There is no such thing as a "noise free"‎ switcher, only unaffected equipment.

As NY9H observed, it also depends on proximity to antennas.

Several years ago, as an increasing number of products entered my home 
and shack with switching wall warts, I adopted the practice of replacing 
them with old "linear" (transformer/rectifier/capacitor) warts and line 
lumps from my junk box. When I ran out of those, I started buying them 
at hamfests (typical price a buck).

I use them two ways. First, by simply cutting the cable from the two 
supplies and splicing them either with crimps or Red/Black PowerPoles. 
I've standardized on PowerPoles for all the low voltage DC in my home 
and shack because it makes it easy to "plug and play" as needed.

The second way is to use the linear supply to float-charge a sealed 
lead-acid battery and run the gear from that. This has the added virtues 
of improving regulation and providing UPS for the gear. I'm doing that 
for computer monitors, some "boxes" in my living room entertainment 
system -- cable box, internet "radio," trucker's FM modulator for the 
internet radio), and another for the cable modem and wi-fi router.

I'm lighting my shack with four LED strips that I bought at the Visalia 
hamfest from Wired Communications. The total draw is 1.25A from the 12V 
battery system that powers my shack. W6GJB did the same with the really 
neat trailer he built for FD, CQP, and other contest expeditions.

73, Jim K9YC

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