[Elecraft] [K2] Aligning CW & SSB filters...Crystal heaters running perfect

[Don Wilhelm]

Mike,

You may want to look at me website www.w3fpr.com K2 Dial Calibration 
article for some information.  Part 3 of that article deals with filter 
alignment, both CW and SSB.
The important factor is to align the -3dB point on the low frequency end 
of the passband at 300 Hz.
The OP1 filter should have a nice flat passband, but the variable width 
filters will show a lot of passband ripple when set to wider than about 
1500 Hz.  Never-the-less, the wide settings are OK for listening the SSB 
at a bandwidth more narrow than the  OP1 filter.

NOTE WELL: The varactors used in K2s for the last one or two years will 
produce a much wider bandpass at settings greater than 1200 to 1500 Hz. 
than that indicated on the K2 display.  Use Spectrogram to measure the 
actual width of the wide variable filters.  With a 2.4 kHz OP1 filter at 
FL1, I recommend setting the actual width of FL2 to 2200 Hz, FL3 to 2000 
Hz, and FL4 to 1800 Hz.  If you set the low frequency passband corner at 
300 Hz in LSB mode, you can then tap BAND+ and adjust the width to place 
the high frequency passband corner without much change in the low 
frequency end - but then tap BAND- and do a fine adjustment on the low 
frequency end before going on to the next filter.  After setting the LSB 
filters that way, do the USB filters without changing the width  You 
will likely find a displayed width of 1.90 will produce a filter close 
to 2200 Hz wide, 1.80 will be close to 2000 Hz and 1.60 will be close to 
1800 Hz wide.

73,
Don W3FPR

Mike-WE0H wrote:
> OK I found Spectrogram 5.0 runs perfect in Wine within Linux. I aligned 
> my CW filters per the N0SS document. All went real easy.
>
> Question though, how to align the SSB filters? What should the filter 
> shapes look like? Is there an online document showing me what I should 
> be tuning them for? I kind of guessed and tuned so the left skirt just 
> went down to the low freq side of the display. I would prefer to see 
> what they should look like when tuned properly...hi hi...
>
> BTW, I have three crystal heaters heating the PLL & both BFO crystals to 
> 40C. So far so good, the radio is dead nuts stable now.
>
> Many thanks,
> Mike
> WE0H
> K2 6698
>   
>