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
 ----- Original Message ----- 
From: "Jim Brown" <k9yc@audiosystemsgroup.com>
To: <tentec@contesting.com>
Sent: Saturday, January 18, 2014 12:21 AM
Subject: Re: [TenTec] On Switching Power Supplies
 
On 1/17/2014 3:44 PM, george fritkin wrote:
 
linear power supplies can cause noise a very proven fact
 
 
 Perhaps you could tell us the mechanism.  I can think of only two -- 
oscillation in a regulator circuit, and improper termination of ground 
wiring.  The latter has nothing to do with power supplies, and the former 
is another engineering goof. .
73, Jim K9YC
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