[Elecraft] KX1 Update: USB/LSB SWL RX modes, wider coverage

[Wayne Burdick]

Several people have asked me whether it would be possible to copy both upper and
lower sideband with the KX1 on all three bands. As of tonight, the answer is yes!

There are now three "RX modes" selectable from the KX1's front panel:

  Normal  (CW mode)
  LSB
  USB

In CW mode, the received sideband that is "normal" for each band is selected,
e.g. LSB on 40 meters and USB on 20 meters. With this mode selected, you
pitch-match to incoming signals to determine their frequency, just as you do
with the K2. (A receive offset is used that matches the sidetone pitch.)

LSB and USB modes can be selected on any band as an alternative. As a few SWLs
pointed out, there's quite a bit of USB activity on the lower SWL bands. Also,
it's sometimes advantageous to be able to listen to one sideband vs. the other
when copying AM stations in the midst of heavy QRM. In SSB modes on the KX1
there's no receive offset, so you tune to the zero-beat frequency to read the
station's frequency. 

Another useful feature of USB and LSB RX modes is that the fast VFO tuning rate
becomes 5 kHz rather than 1 kHz. This allows you to step conveniently from one
AM station to the next, and it permits rapid QSY across SWL band segments. Of
course you still have the 10 Hz and 100 Hz tuning rates available in these modes.

In all three modes, you can make cross-MODE contacts in the ham bands (that is,
with you transmitting CW and the other station transmitting SSB). No adjustment
of the RIT control is required, and the SSB station will always hear your CW
signal at about a 600 Hz pitch once you've tuned them in. In CW mode this is
handled by a receive offset, as described above. In USB and LSB modes it's
handled by a *transmit* offset (i.e. your TX frequency is shifted down 600 Hz in
LSB mode, and up 600 Hz in USB mode).

The VFO frequency range on each band has now been finalized:

  40 meters:   5 to  9.5 MHz
  30 meters:   8 to 12.5 MHz  (requires KXB30 option)
  20 meters:  12 to 16.5 MHz

The KX1 has a double-tuned band-pass filter at the front end, which is typically
peaked in each of the three ham bands, so signals will drop off in amplitude
somewhat as you go well outside these bands. Despite this, signal levels are
still quite good in the principle broadcast SWL segments. I was just listening
from 5.9 to 6.2 MHz tonight (with 40 meters selected), and it was wall-to-wall
strong AM signals. The DDS is very stable, so you can even listen to music
without continually tweaking the VFO.

Even WWV at 5 MHz was quite strong. The KX1 can now copy WWV at 5, 10, and 15 MHz.

73,
Wayne
N6KR

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