[Elecraft] Switching power supplies...yet another comment

[John Ragle]

     This topic goes around every few months, and I hesitated 
(unsuccessfully) to add to it this time around.

      I have several inexpensive 25-amp switching supplies from Radio 
Shack and Pyramid. I also have a couple of "linear" supplies that are 
built like the battleships of yore, and some gel batteries for portable 
operation.

     I have used these supplies in various combinations on a K2/100, a 
K3/100, and an ICOM 910H. I have never been able to tell the difference 
in noise level between any of these sources. My two rigs sit ~2 to 3 
feet from a computer,and I have occasionally also put a small laptop 
directly in front of the XCVRs. Same comment: no discernible noise from 
the computers...they are impressively shielded with finger-stock, etc. 
Some lines have ferrites on them because that's the way they came from 
the factory.

     I do have a few birdies up and down the bands, but these are 
apparently from external sources and disappear when I disconnect my 
antennas or switch over to my dummy loads. My antennas are fed with good 
quality coax, and I live in the boonies. The nearest above-ground 
utilities are a city block away. I imagine this is a fairly quiet location.

     When I bought my first K2 I was concerned about this question, 
hence the linear supplies. My current take on this question about 
switching power supplies is that it is/was a needless worry. I suppose 
that if one is using open-wire feeders the situation might be different?

John Ragle -- W1ZI