[Elecraft] Switching Supplies

[Bill Coleman]

On Jul 8, 2008, at 8:40 AM, Jan Erik Holm wrote:

> Mike Penkas wrote:
>> I  have 2 SEC1223's and no hash. I also have an Astron RS35 and  
>> RS50 linear supplies.  Sometimes the magnetic hum from them drives  
>> me crazy.  The little cork pads Astron puts in them to alleviate this
>> does not help much. I keep them under the closed console on the  
>> floor.
>>                     Mike  WA8EBM
>
> Sorry to disagree but the SEC1223 is far from quiet. However it can
> be made much better by modifications. The DC side needs much better  
> filtering, also some work can be done on the AC side.


I bought a used SEC-1223 at a hamfest to power my K2. I found it  
reasonably quiet on all bands except 160m. I added ferrite beads and  
bypassing to the DC output, and more ferrite to the AC leads and all  
but knocked the birdies completely out of the picture on 160m.

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901