Should you elect to use any "open frame" type supply then you should EXPECT
to add required filtering such as a CORCOM {check the specs of the one you
use} and also add RF filtering in the form of lumped constant inductance on
the output leads. Yes "leads" plural meaning both the Pos and Neg leads.
I have some nice Lambda supplies, open frame type that provide excellent
voltage regulation and very low residual noise on the DC line. However,
filtering is required on the input and the output as well as a suitable
enclosure.
73
Bob, K4TAX
----- Original Message -----
From: "Al Gulseth" <wb5jnc@centurytel.net>
To: <tentec@contesting.com>
Sent: Saturday, January 18, 2014 8:36 PM
Subject: Re: [TenTec] On Switching Power Supplies
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@Blomand.net>
To: <k9yc@arrl.net>, "Discussion of Ten-Tec Equipment"
<tentec@contesting.com>
Subject: Re: [TenTec] On Switching Power Supplies
Message-ID: <35D28D15AFA24BBCA4C39FE114C3A7F4@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
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