[TenTec] On Switching Power Supplies

[Al Gulseth]

Speaking of "switchers" - I've been looking around for a small 3-4A PS 
suitable for use with QRP/QRPish rigs (TT examples: Argonauts, 1220, 13xx, 
etc.) and would like something a little more portable than the surplus 
Power-Mate linear supply I have now. Has anyone had any experience with the 
MFJ, Samlex, RS etc. of this ilk and/or any of the open frame stuff the 
surplus outfits sell? (I know quality and RFI output can vary widely with 
these: what I'm thinking might be the best possibility would be a good name 
brand - Condor comes to mind, especially their medical grade products.)

If it's an open frame type, I'd assume a suitable enclosure and a Corcom-type 
line filter as well as some additional output filtering would be in order. 
Also, would a 12V or a 15V be a better starting point to readjust to 13.6-8?

Or, even though it's a little bigger would I be better off just going for an 
Astron SS-10 or 12 since they seem to get pretty good reviews regarding RFI 
along with the added benefit of having enough "oomph" for an Argosy or Scout? 
Comments/suggestions?

TNX/73, Al

On Sat January 18 2014 11:00:13 am Bob McGraw wrote:
> Date: Sat, 18 Jan 2014 09:28:29 -0600
> From: "Bob McGraw - K4TAX" <RMcGraw at Blomand.net>
> To: <k9yc at arrl.net>, "Discussion of Ten-Tec Equipment"
>         <tentec at contesting.com>
> Subject: Re: [TenTec] On Switching Power Supplies
> Message-ID: <35D28D15AFA24BBCA4C39FE114C3A7F4 at FAMILY>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>         reply-type=response
>
> I've found a very few linear power supplies generate noise.  However those
> that do I've found are largely due to deteriorating decoupling capacitors
> in the regulator circuit or due to a highly reactive load on the output.
> Typically the oscillation can be from a few Hz to over 100 KHz and equal in
> amplitude to the output voltage.  Real nasty stuff.
>
> A well designed and manufactured power supply, be it linear or switcher,
> will not generate any objectionable noise.   Any noise generated has been
> found to be several dB below the typical noise found on the HF bands and
> even VHF bands.
>
>
>
> 73
> Bob, K4TAX