[Elecraft] K3 - what power supply are you using?

[Jim Brown]

On 10/11/2012 5:01 AM, Bill wrote:
> I have a very large deep discharge battery and the West Mountain
> distribution and charging stuff.

Since 2004, I've been using the biggest deep discharge that Costco 
sells, float-charged by a 10A switcher that I paid $10 for at a hamfest. 
It was VERY noisy until I did suppression on it with toroids and 
capacitors.  Batteries typically last four years and provide great 
backup power.  I have two K3s in an SO2R setup, two batteries, two 
chargers, all wired in parallel.

As to Joe's comments re: IMD -- short fat copper from battery to K3 
helps minimize the drop. I do NOT use any charge regulator circuit, but 
have the regulator in the 10A supply set for 13.8V, which has proved 
very good for battery longevity.  The result is about 12.3VDC keydown 
with 100W.  I'm usually driving an amp, so my K3s are running between 30 
and 45W, resulting in 12.6V keydown.  I've looked at IMD with a spectrum 
analyzer (I own the same one that Elecraft uses), and it's been quite 
good, but I haven't studied the effect of power supply voltage.

Several years ago I bought a PowerWorks 20A switcher to take on a DX 
trip, and checked it out for RF noise.  I didn't hear any, but it mostly 
sits in my storage area. We used it in the same battery charging circuit 
for a California QSO Party county expedition last week and it worked 
well with no noise.

73, Jim K9YC