[Elecraft] K2 CW CALFIL method

[Don Wilhelm]

----- Original Message ----- >
> Would something like this work for SSB? I don't even know how to zero-beat
an
> SSB signal. I guess you have to know what the OM or YL is supposed to
sound
> like, and then twist the knob until s/he sounds right? Hummmm.
>


Don, Dan and gang,

Setting the SSB filters is a bit more complex than the CW filters - but it
need not be any more difficult if you are using Spectogram or some other
spectral display.  The procedure goes like this:

1) Determine the filter bandpass you want to use - if you have the SSB
option installed, use the OP1 filter.
2) Use a noise source (no signal) - a noise generator is best, but 'empty
band' noise will do fine too.
3) Looking at the Spectogram display - set a marker at 300 Hz (set a second
marker at 2300 Hz too if you desire - that one is not critical, but may help
you observe the passband)
4) Start with LSB.  By changing the BFO frequency - move the passband so
that the 300 Hz marker is 3 to 6 dB down from the top of the passband (it
will appear approximately 1/3 down on the Spectogram display - exactly how
much depends on your noise source and the noise floor of your computer
soundcard connection).

That is all there is to it - you should now be able to easily tune SSB
signals.  You can go back and shift the 300 Hz response to better suit your
ears if the recieved audio from a good SSB signal sounds too high or too
low.
Repeat for USB and any other variable filters that you would like to set for
SSB.

You will find additional information (with pictures - complements of Tom
Hammond N0SS) on the Elecraft website -
http://www.elecraft.com/Apps/new_fil_docs/k2_ssb_gram.pdf  click this link
or dig deep into the filter setting portion of the Builder's Resource page.

5) Now take a break and check the response in SSB transmit - this will
require a second receiver to listen to your transmitted signal or another
willing ham.  Tape record the receiver output and listen critically.  If
your voice lacks sufficient lows, change the BFO to move the passband a bit
lower - if it is too low (and hard to tune) move the passband higher.  Using
this method will customize OP1 and BFO1 to your individual voice - remember
that BFO1 is always used for transmitting SSB.

BTW - the same procedure works FB for setting the digital mode filters -
just figure out what the audio tones are that are used for the data mode you
want to set up for and make certain that all tones fit easily within the
passband - set the BFO to make that condition occur.

73,
Don Wilhelm  - Wake Forest, NC   W3FPR home page: http://www.qsl.net/w3fpr/
  QRP-L # 485   K2  SN 0020   mailto: w3fpr@arrl.net