[Elecraft] Walwarts - linear supplies

[Jim Brown]

Older wall warts are linear.  If you're smart enough to have saved them, 
there's a good chance you won't have buy anything.  Simply select one 
with the matching voltage and rated for the needed current, cut the 
cables to both old and new warts, splice the old wart to the connector 
that mates with the unit you need to power.

Older warts are often available at second hand stores and flea markets. 
$1 is the going rate. In general, linear warts are much heavier than 
SMPS units, so that's a good first check. A better one is to plug it 
into AC and hold a portable radio next to it tuned somewhere near 2 MHz 
(like the top of the AM BC band). If you hear hash, it's a switcher. If 
you don't., 99% chance that it's linear.

All of this is described in http://k9yc.com/KillingReceiveNoise.pdf

73, Jim K9YC

On 11/20/2017 1:17 PM, Joe Subich, W4TV wrote:
> All Electroncs (www.allelectronics.com) has analog wall warts of various
> voltage/current capability depending on what is available in surplus at
> any given time.  One may not even need regulated voltage as many devices
> contain internal regulators ...