[Elecraft] K2 Mods

[Don Wilhelm]

DW,

Yes. I have a LOT of opinions!  I am glad to hear that you honor some of 
them!

For the Fixed Audio - yes, use the newer low profile board from Tom 
Hammond (see his website www.n0ss.net) and mount it between the front 
panel and the control board - then take the output to a spare microphone 
jack pin.  I do that by plugging it in at the microphone configuration 
header, but you can be creative about the method.  Remember to remove 
the mic configuration header jumper to the internal K2 circuitry.  While 
I say 'spare' mic pin, that is a dependency on your microphone wiring - 
all the pins could be connected at the mic configuration header to some 
circuits inside the K2.

Yes, the switchbox for digital modes can allow you just one cable to the 
K2 if you wire the audio output as above.  I have built a couple new 
versions, but all are basically the same.  You can mount transformers in 
the switchbox if you want isolation, but you might want to read what Jim 
Brown (of this reflector - see his recent posts) has to say about the 
benefit/non-benefit of transformers in the audio lines.

As far as defeating the SSB compression for data modes - there is a NEW 
way (compliments of Elecraft firmware).  Version 2.xx of the K2 firmware 
added a set of RTTY filters.  The most important item is that the RTTY 
mode has a compression setting independent of the setting used for SSB.
When setting up the RTTY filters, I set the FL1 position the same as SSB 
FL1 (using the OP1 filter), but the other 3 filters I set much more 
narrow - 1.00, 0.70 and 0.40 Hz, and center these narrow filters at 1000 
Hz.  In operation, if you tune with the VFO knob to place the desired 
signal near 1000 Hz (rather than just simply clicking with the mouse 
over a wide range) - when a strong station enters the passband near your 
desired station, you can just narrow the filter down and (hopefully) 
avoid the AGC pumping that is created by the strong unwanted station. 
Note: if you operate that way, you should lock the transmit frequency in 
the software before switching to a narrow filter to keep the QSO from 
walking the band due to slight changes in the BFO frequency from filter 
to filter. (you should not retune with the VFO - this time the mouse 
will do the tuning, but the transmit frequency should not change).

OK, now you have most everything I can say on that subject. Above all, 
have fun with it.

73,
Don W3FPR



DW Holtman wrote:
> Hello,
> 
> I finally got around to installing the CW LED tuning indicator by Tom Hammond N0SS. It works great, I should have put it in way back when, upon completion of the K2. It is both sensitive to weak signals and selective.
> 
> Next I'm thinking about putting the Fixed Audio Output for digital modes created by Don Wilhelm W3FPR. It looks very well designed. Don has put a lot of time and effort into this project to design, build and document so everyone can read and understand it. Have many put this in and are you happy with the results? I'm a little nervous about drilling holes in the back panel.
> 
> Don also has a another project on his very informative web page. This is a switch box to make the connections from Digital modes to SSB without unplugging cables and changing the compression settings on the SSB Board. Has anyone built this and how do you like it? Would it be possible to combine the two. So a fixed audio would be applied to the mic plug to use in the switch box? This would also eleminate drilling the back panel?
> 
> I did not know if I should send this to Don, since he is the expert on most things related to the K2. But, I thought I would send it to the group for any ideas and hopefully Don will let everyone know what he thinks.
> 
> Best,
> DW Holtman
> Wb7SSN
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