[Elecraft] When reporting Switching Power Supply Results...

[Tom Hammond]

Folks:

One (semi-)important point which can be easily forgotten when reporting 
usage results from switching power supplies is the failure to describe the 
type of antenna/feedline conditions you are using with your setup.

If you are using an antenna/feedline combination which places the antenna 
some distance from the rig, there's little chance you will notice the 
presence of RFI from a 'noisy' switcher, even if it might be pretty noisy.

By the same token, even the quietest of switchers might be tagged as 
'noisy' if the user is using a 'long wire' antenna (any length wire, 
terminated AT the back of the rig or the ATU), with some for of counterpoise.

So, we really need to have some frame of reference when we post comments 
about our switchers.

So far, my experiences with my Samlex 1223 switcher has been very positive. 
I have used it on all bands, 10 thru 80M, at our 2003 Field Day operation, 
with both a coax-fed 80/40 dipole thru about 100' of coax, and a coax-fed 
Butternut vertical thru 100' of coax as well. I have also used the Samlex 
1223 at a portable operation on 10 thru 40M with a 70'/30' off-center-fed 
dipole, fed with only 15' of RG-174 mini-coax. At neither of these 
operations did I detect any hint of RFI coming from the Samlex switcher. 
this doesn't necessarily mean it was 'clean'... it just means that I didn't 
FIND any noise during my operation... I may have just not tuned across the 
noise, OR it might have been hidden under the QRM/QRN.

73,

Tom Hammond    N0SS