[Elecraft] K2 working on 40M

[2rGarry]

Thank you Don.   I think the most confusing part of all was, I was
looking for various width settings for the ssb filters.  Eventually I
came to realize that I had to use the other filters for reduced
bandwidth for ssb.  After that dawned on me it was relatively easy.
Or perhaps I still have not got it correct.  Still can't get the
display on frequency.  I guess I need a decent freq counter.  Can't
seem to manage with wwv.

cheerio and 73.

Garry

On Thu, Feb 11, 2010 at 8:52 PM, Don Wilhelm-4 [via Elecraft]
<ml-node+4559453-248936129 at n2.nabble.com> wrote:
> Garry and all - at least those who are building new K2s.
>
> Yes, the filter setup is a bit "tricky", especially when using filter
> widths wider than 1.00 kHz.  The reason is in the varactors that have
> shipped with the more recent K2 kits.  What that means is that a filter
> width that is indicates as 2.00 kHz wide on the K2 may actually be 2.5
> kHz wide (this is not exact, it all depends on the varactors).  The
> result of this is that the LSB filter settings listed in the manual will
> be about right, but the USB settings will be way off.  In other words,
> the manual settings will give you a workable filter for the lower
> sideband response, but will not work for the upper sideband (USB, RTTYr,
> and CWr) settings. (NOTE: the OP1 filter width is not affected by the
> varactors - there are no varactors on the KSB2 board).
>
> The only cure I know is to use Spectrogram or another audio spectrum
> analyzer to measure the actual width of the filter (in LSB or CW - not
> CWr -  or RTTY - not RTTYr).  When you use LSB, CW or RTTY, you should
> be on the lower sideband, and you can change the width without much
> movement of the lower end of the passband frequency.  After getting the
> filer width as you like it, then refine the low frequency end of the
> lower sideband filter (by changing the BFO setting) and then set the USB
> BFOs to properly place the sideband.
>
> If you want specifics on how to set the filters, look at part 3 of the
> article on K2 Dial Calibration at my website www.w3fpr.com (while you
> are there, you may just want to go through the entire K2 Dial
> Calibration procedure which includes adusting the filters.
> I have not yet updated the webpage information to include how to handle
> this "varactor problem", but since you can see the passband width on the
> Spectrogram display, it should be obvious.  Just adjust the width of the
> filter until the actual width is what you want, and use the K2 display
> only as a relative indicator.
>
> 73,
> Don W3FPR
>
> 2rGarry wrote:
>> Congrats on the K2 receiving on 40.  It's only a month or so back that I
>> finished mine so easy for me to remember the thrill of hitting the switch
>> and having it come up working.  I used mine on cw for a week or so then
>> went
>> on to the ssb board which allows digital modes as well as phone.  Still
>> using it qrp here and may never buy and build the power amp as I have been
>> having a blast with it even on qrp.
>>
>> If you chose the ssb option perhaps you will find as I did that the
>> directions for setting up the filters are somewhat confusing however it
>> will
>> all fall into place eventually.
>>
>> Cheerio, maybe hear you on the air sometime.
>>
>>
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