[Elecraft] K3 Hardware Updates

[Brett Howard]

haha wow I just did the doubles rather than doing all off the harmonics.
Ok its time to go and get some sleep.  The 3 hours I got last night were
not enough.

~Brett

On Sun, 2009-08-23 at 17:09 -0700, Brett Howard wrote:
> Actually I believe that the signals will be plenty stable if you place
> the hardware mod but don't change the frequency.  However speeding
> things up (using the SPI2 setting) w/o proper termination is going to
> cause problems.  
> 
> I think the reason for the speeding up of the clock was to put the
> harmonics out of the bands.  The previous frequency was 1Mhz where as
> with SPI2 its set to 4Mhz.  That puts the harmonics at 4Mhz, 8Mhz,
> 16Mhz, 32Mhz (and then we are out of the range of the rig).  Notice that
> none of these fall inside of Ham bands..  You'll also note that the
> areas where you are told to look for the noise is at the even 1Mhz
> multiples.  
> 
> The diode and R combo allows for the R's to only be in play when the
> Chip Select for those particular components is activated (low).  Its a
> pretty darn slick idea.
> 
> ~Brett (KC7OTG)
> 
> On Sun, 2009-08-23 at 16:08 -0700, Ron D'Eau Claire wrote:
> > Well, it shouldn't hurt to do the mod, but I agree with David if you can't
> > find any noise.
> > 
> > The reason 3.24 is required is that it provides a menu entry for changing
> > the bus timing as described in the procedure. A slightly different timing is
> > required for stable operation once the diodes and resistors are added. 
> > 
> > If you try to load the firmware and change timing without adding the
> > resistors and diodes, or if you add the resistors and diodes and do not
> > change the timing, the VFO may become unstable, making un-commanded QSYs.
> > (On my K3 they were in 100 Hz steps.) 
> > 
> > The default timing in all the firmware, including 3.24 and up, is correct
> > for K3's that do not have the diodes and resistors added, so you need do
> > nothing after upgrading your firmware if you haven't added the parts. Your
> > K3 will continue to work FB just as always. 
> > 
> > A revised mod procedure will be posted Monday to make that point clear. 
> > 
> > Ron AC7AC
> > 
> > -----Original Message-----
> > In a recent message, Roy Morris <w4wfb at carolina.rr.com> wrote ...
> > >
> > >Now that my K3s have v. 3.25 firmware,
> > ...
> > >  While I have access to the PCB, why not go ahead and install the VFO 
> > >tuning noise reduction mod even though I do not experience noise during 
> > >VFO rotation on 6, 10, and 60 meter bands.  You might say "if it ain't 
> > >broke, don't fix it".
> > 
> > The mod notes for the VFO Tuning Noise Reduction do say, in bold type..
> > 
> > "IMPORTANT:  You must complete the modification as described below 
> > before using firmware version 3.24 or later. Failure to do so will 
> > result in erratic behavior of your K3."
> > 
> > That seems to imply that even if you don't notice to be broke, it may 
> > be.
> > 
> > 73
>