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

[Vic K2VCO]

I think a lot has to do with the antenna, and how it's connected to the rig. If you are 
using a balanced antenna, properly fed with coax and a balun or two-wire line with a 
well-balanced tuner, it's unlikely that you will have a problem. If you have a wire stuck 
in the coax connector of your rig, then you almost certainly will. Other setups will be in 
between.

A dipole fed with coax with no balun will certainly be vulnerable to picking up noise on 
the outside of the shield. Noise currents flowing on the shield will then be connected 
directly to the antenna at the feedpoint! If the coax runs near power wiring which is 
connected to a switching supply (or computer, etc.) then you are asking for trouble.

Having said that, I'm sure some switchers are worse than others. But it's very hard to 
make one at consumer prices that doesn't allow some noise to escape.

On 7/17/2010 7:13 AM, lstavenhagen wrote:
>
> My experience is the opposite - I haven't yet used a switching PSU that
> _didn't_ cause some kind of nasty noise in my rigs, usually like computer
> generated noise. A broadband hash with spikes of hum at various places is
> usually what I get.
>
> I simply threw batteries at the problem - now I exclusively use my 80AH
> wheelchair battery for my K2 and K3 with no more troubles. The PSU's either
> went in the trash or were sold, and the money was used to buy my battery....
>
> 73,
> LS
> W5QD


-- 
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/