[RFI] ONE wallwart

Sat Aug 31 20:40:25 EDT 2013

Excellent advice from Dale. In addition to PowerOne and International Power, Condor is the third company making nearly Identical linear supplies. I use all three brands. 

As Dale noted, these are OEM supplies and require the user to supply a power cable or power entry module along with a fuse. The output feeds a PowerPole splitter.

In my home office, the router, file server, and cable modem are all fed by one PowerOne supply.  That significantly reduced trash from three separate switching supplies. 

Used Lambda supplies are even better but overkill for most applications. 

Paul, W9AC

Sent from my iPhone5

On Aug 31, 2013, at 1:52 PM, Dale <svetanoff at earthlink.net> wrote:

> Charlie,
> 
> Yes, there are places to go get "clean" linear power supplies, but they are getting fewer by the year.  There are 2 commercial vendors I can recommend, strictly on the basis if having been a happy customer. They are Marlin P Jones & Associates, in Florida, and Jameco Electronics, in California.  There might also be choices at Mouser Electronics and Digi-Key, but I have not seen their catalogs or web sites in a long time.
> 
> First, MPJA:  Go to their web site <www.mpja.com> or contact them at (800) 652-6733 for details or a catalog.  They are a distributor of International Power open frame LINEAR power supplies.  I have used that brand (or their main competitor, Power One) in previous industrial applications.  They are butt-ugly (and rather large) units built on a one-piece aluminum L-shaped chassis, and the 5V and 12V versions are both available in output current ranges of around 1.5 amps to more than 15 amps.  They are made in USA (as far as I know) and the cost is around $40 for the small ones and upwards of $250 for the much larger ones.  They use easy to get replacement parts, have full UL safety approvals (real, not fake), and the power transformers have dual primary windings so that you can wire them for 120 or 240 volt operation.  If appearance is not important, or if you can make or buy a housing, this is a very good approach to consider.  The smaller models are around 4.87" by 4" by 2.1
> " and weigh 2 lb.  
> 
> Jameco: They carry a line of wall warts, most being switchers, but there are several linear types, as well.  Google them for web site and see what they have.  Note that some of the wall warts are unregulated types - meaning that they produce the rated output voltage and current at rated current load, but output voltage can be a lot higher with light loading.  (Example: A wart rated for 12VDC output at 2 amps might very well deliver almost 18VDC at less than 0.5 amp load.)
> 
> A caution about the 19V supplies for computers: In some cases, it only seems as if the laptops have a common type of DC power connector.  However, it has come to my attention that Dell computers, in particular, "know" when the power supply is not an OEM original or equivalent.  When that happens, it is my understanding that the battery is either not recharged at all or at a very slow rate.  Therefore, you might check around before trying to replace an OEM computer wall wart with something else.  You could be stuck with a switcher.  I am typing this on a Dell laptop and the switcher powering it is OK, as long as you don't get either the lap top or the wall wart within 5 feet of an AM broadcast band radio that you wish to use while on the computer.  Thank you, FCC, for no required radiated emission limits in that frequency range.
> 
> Bottom line: Be prepared to give up some degree of portability if you want clean DC power.  Compactness, light weight, low cost, and universal voltage operation are all long suites in favor of switchers.  Consider that maybe you only need clean power in or near your shack, so a larger, more hefty linear supply might be the answer there and save the switchers for other applications.  OTOH, if you really do want small linear wall warts and do not find what you need at a dealer, then ham fest junk bins really can be THE place to look.  Those bins may well contain perfectly good linear "clean" supplies that were the norm 15 to 25 years ago.  It's all about trade-offs (and keeping your HF antennas as far away from the house as possible).
> 
> 73, Dale
> WA9ENA   
> 
> 
> 
> 
> -----Original Message-----
>> From: Charlie Gallo <Charlie at TheGallos.com>
>> Sent: Aug 31, 2013 8:37 AM
>> To: rfi at contesting.com
>> Subject: [RFI] ONE wallwart
>> 
>> Hey Gang,
>> The cable TV issues are still there (but there no longer seems to be voltage on the line), but I've pretty much did a good cleanup on the higher bands
>> 
>> Last night I go to look at a spot on 80m - s9+10 noise!
>> 
>> Start searching this AM - the power supply for my WD-TV that I had a small ferrite on was still making some noise on 80, but even with it unplugged, there was something in the house SCREAMING
>> 
>> I chased it down - the power supply that came with my (cheap) external had drive enclosure from Buffalo - unplugged that, I'm down to S4 - Yep, over 5 S units of noise from ONE wall wart (simple 12V unit!)
>> 
>> DOes anyone know where to BUY (no, I'm not talking hamfest junk bin finds) various portable (No, I don't want to lug around an Astron) power supplies that are RFI Quiet?
>> 
>> The big ones (in my household survey) would be
>> 12V DC
>> 20V DC High (like 20A) power 'line lumps' for laptop computers - those seem to be all noisy, but seem to use a standard connector
>> and 5V DC
>> 
>> I'd actually be willing to spend some fairly nice money to replace them.  There are so many of them around the house that the cost in ferrites....
>> 
>> -- 
>> 73 de KG2V - Charles Gallo
>> Quality Custom Machine-shop work for the radio amateur (sm)
>> 
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