[Elecraft] Wall wart for KX3

[Matthew Zilmer]

George has an excellent point (killing good radios), but be advised that the KX3 is designed to work from pure DC power (batteries) and doesn't tolerate power supply ripple and transients well.  So filtering of the DC is necessary as well as good regulation.  Most wall warts out of the box have neither.  This comes true in spades, in a mobile installation (see http://www.elecraft.com/manual/Rev-B1-1.6-KX3-Mobile-Owners.pdf for more on mobile installations and ops).  

My "on the road" AC supply is a MeanWell switcher.  It's got a few broad HF spurs.  I treated these as conducted emissions and used a Laird LFB174095 ferrite core w/ 5 turns through it to suppress them.  There are still a few spurs being radiated, and even though they're broad they are also below the atmospheric noise level.  KX #6 only hears them with the antenna cable disconnected.

Matt Zilmer
Consultant - Product Management Dept.
Magellan Navigation / MiTAC Digital Corp.
Tel: (909) 394-6052
Cell: (909) 730-6552
In status quo voluntas non sufficit


-----Original Message-----
From: elecraft-bounces at mailman.qth.net [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of W2bpi1 at aol.com
Sent: Wednesday, December 19, 2012 8:12 AM
To: Elecraft at mailman.qth.net
Subject: [Elecraft] Wall wart for KX3

I bought several 18VDC ones and pried them open. There was enough room  
inside to add a regulator and extra filter cap. Used with other QRP rigs but  
never with a KX3. Yes mni wallwarts will kill a good radio!  72  George/W2BPI
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