[Elecraft] Kx3 supply

[Dave Van Wallaghen]

Thanks Jim. I always have an updated version of your tutorial on my laptop!

Eric alluded to some type of internal change and that is what I was 
hoping to get info on. But I will certainly try your suggestions (most 
likely either way) if I can't find the info or it turns out to be 
unfeasible with my version of that supply.

I have not really had too many problems with RF noise with this unit. I 
use it when I'm portable and have noticed if I use a ladder line fed 
doublet, that if the ladder line is in close proximity I will pick up 
some noise (sweeping noise). If I use a small length of coax to a balun 
with the ladder line (pushing the ladder line further away), I don't 
notice the noise as much.

Anyway, thanks for the info as always.

73,
Dave W8FGU


On 4/7/2012 1:42 PM, Jim Brown wrote:
> On 4/7/2012 10:24 AM, Dave Van Wallaghen wrote:
>> I would be interested to see if I could
>> make the change myself.
>
> I cleaned up a couple of cheap switchers that I  bought at a hamfest by
> adding a line-voltage rated capacitor across the AC line, an RF cap
> across the DC output, and serious multi-turn ferrite chokes to both the
> AC line and the DC output.  I also added a couple of clamp-on cores to
> kill the stuff on 2M.
>
> Total cost of my clean-up was about $10 (I bought the cores as part of a
> group purchase for $4 each), and the power supplies cost me $10 each.
> Doing it right when they built them would probably have added less than
> a buck to the cost, and most of doing it right is circuit layout, not
> components.  See my RFI tutorial for guidelines on winding the chokes,
> and also for detailed info about line-voltage rated capacitors.  Hint --
> they must be rated for the surges of several kV that often occur on the
> AC line.
>
> 73, Jim K9YC