[Elecraft] Re: K2 and MFJ-4125 Switch Power Supply

[Ron D'Eau Claire]

For low-current applications like the K2 (up to 15 amps or so) I stick
with linear supplies too. I do not need the light weight for portability
and I like the inherently quiet operation. 

The only critical issue, where the K2 (and maybe some other rigs) is
concerned with a linear supply is to keep the rig AWAY from the power
supply. When I first fired up my K2, I plopped the K2 on top of the
supply. That's a very common practice in the commercial world, and my
power supply is almost the same size as the K2. 

My first QSO's reported hum on my signal. Hooked up a dummy load and
listened on an aux receiver and it was clean. Back on the air and there
was another hum report. It too a couple of iterations before I realized
that I was pulling the K2 off of the power supply to hook up the dummy
load and testing with it sitting on the desk. Put it back on the power
supply and there was the hum. The big 60 Hz field around the transformer
was modulating one of the VCO's in the K2.  

Ron AC7AC
K2 # 1289

===========

Jim, WA2UMP wrote:

"Do you prefer a linear PS over the switching PS ?"
==========
When you're trying to dig that weak signal out of the noise, you don't
want to have to contend with even the slighest bit of hash.

I bought a new MFJ-4322 linear 22-amp power supply from AES for $69 a
while back that I'm completely satisfied with.  It's more than ample to
power my K2/100 (and hopefully my new Ten-Tec Orion when I get it).  I
don't know if AES has any of them left at that price.

73, de Earl, K6SE _______________________________________________
Elecraft mailing list: Elecraft@mailman.qth.net
You must be a list member to post to the list. 
Postings must be plain text (no HTML or attachments). 
See: http://mailman.qth.net/mailman/listinfo/elecraft
Elecraft Web Page: http://www.elecraft.com