I also installed the LPF in 2 K3s here this weekend. Although I have pretty good hearing, I was skeptical about any possible improvement. However, I was surprised when I turned on the 1st unit completed. The improvement was noticeable (I use headphones with a wide frequency response). CW notes are purer, and atmospheric noise less grating. AF output from the headphone jack looks very clean now when viewed on Spectrum Lab, previously the artifacts were no better than 60 dB down with strong signals. There is no change to the line out audio, which uses a separate DAC and audio path.
All vias were solder filled on both units, but I was able to clear them with solder wick and the installation went smoothly. The instructions are very clear. I also did not make the change to extend low frequency response. Bob NW8L On Mon, Mar 1, 2010 at 11:02 PM, Joe Planisky <jp...@jeffnet.org> wrote: > 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 > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
