[Elecraft] KX3 external battery (Maxtron) VERY NOISY

[Jim Brown]

On Fri,3/6/2015 12:43 AM, Dominic Baines wrote:
> Yeah it is an oxy moron sometimes... operate off grid using a battery 
> and you get noise (this will be the internal LiION battery 
> recharging/regulation circuitry causing it).

Probably so.

>
> Have you tried adding ferrite to the DC leads (and weirdly to the 
> headset leads, I need to if using ext battery sometimes). You could 
> make up a simple choke and plug your rig power lead into that, doesn't 
> need to be in a box or anything... leads from battery then 12 turns of 
> the power leads or so in opposite directions in parallel on the 
> ferrite (try FT240-61) to a set of connections to the rig. 

#61 is a VERY poor choice for suppressing noise at HF.  #31 and #43 are 
the weapons of choice for the HF bands.

> Or a string of those little 5mm ID clip on ferrites (ebay) on the 
> Elecraft lead. 

Strings of beads or clip-ons are NOT effective at HF. Study

k9yc.com/RFI-Ham.pdf

73, Jim K9YC