[Elecraft] K3DSPLPF Low Pass Filter

[Joe Planisky]

I recently installed the LPF.  I did *not* make any other changes  
(e.g. to extend the low frequency response.)  I work mostly CW but do  
a fair amount of listening to SSB and SWBC.

In my case, the effect is rather subtle and I can't be sure it's not  
just a placebo effect, but I think CW notes and SSB voices sound a bit  
smoother.  I haven't used it for a long period of time since I  
installed the LPF, so I can't really tell if it's less fatiguing.

Like Brett, I have before and after spectrum plots which clearly show  
that the aliased passband images centered on 12 kHz are completely  
gone.  However, in my case the 12 kHz clock leakage itself is still  
there.  It must be getting into the output some other way than through  
the normal audio path.

It was one of the more challenging mods that I've done to my K3,  
mostly due to the fact that 4 of the 6 vias used were filled with  
solder, two of which have an IC on the other side preventing the use  
of a hot needle to clear them. And I'm *always* nervous cutting  
traces.  That said, it wasn't really difficult.  I took my time and  
spent about 2 hours from power off to power on.

I noticed the price on the LPF board has gone up to $35.  When I  
ordered mine it was $25.  Was it worth it?  I think so.  I wouldn't  
call it a whole-new-rig difference but I seem to think the rig is a  
bit more pleasant to listen to.

73
--
Joe KB8AP


On Mar 1, 2010, at 8:40 AM, Edward Dickinson, III wrote:

> I'm a SSB operator and am interested in the Low Pass Filter Update/ 
> Mod.
>
> Can someone with a pre-Rev D DSP board who has installed the  
> K3DSPLPF speak
> to the improvements?
>
> Thanks.
>
>
> 73,
> Dick - KA5KKT
>