[Elecraft] Power Supply For K3?

[Jim Brown]

In the old days, I used an Astron linear supply to run my 12V radios. 
Soon after I got back on the air in 2003 after a long period of 
inactivity, I adopted the practice of using a small regulated supply 
(about 10A) to float-charge a big 12V deep-cycle battery (about 110AH)  
that I bought at Costco for about $70.  The supply regulates to 13.8V, 
which never overcharges the battery, so it lasts a long time and serves 
as a poor man's UPS.  The radio runs very well, and the battery will 
keep it running through a power failure of moderate length. I run 
several accessories, a VHF rig, and the dial lights for several antenna 
tuners from this rig, and it's big enough to keep up with heavy contest 
operation as long as I have AC power. Just last fall,  I replaced the 
battery that I bought in 2006 when I moved to CA. This time it cost $75.

This sort of setup would work just fine with one of the el-crappo 
computer supplies that have been described here. If it's a switching 
supply, be prepared to do some suppression. The PSU I use is a 10A 
switcher that I bought for $10 at a Chicago hamfest around 2004. I added 
caps across the DC line and ferrite chokes on both the DC line and the 
AC cable.

73, Jim Brown K9YC