[Elecraft] DDS K1.

[Mike Morrow]

> Ah, if only we could get a K1 with a DDS VFO!

Absolutely NOT!!!  True, a DDS VFO adds crystal-like frequency
stability, and frequency-change agility.  But it also adds many
spurs on its output that increase spurious emissions on transmit
and spurious output of the receiver local oscillator to degrade
receiver performance.  (All this assumes that DDS output is being
used in the signal paths directly, as it is in the KX1, rather than
to synch a phase-locked loop voltage controlled oscillator.)  If
good RF performance is an important criteria, one will always be
forced to choose an LC VFO over a direct use of DDS in the signal
path.

Traditionally, DDS chips have been power hungry, although the KX1's
AD 9834 is very good in that area.  Its maximum clock frequency
of 75 MHz (earlier, 50 MHz) limits it to frequencies below 25 MHz 
(earlier, 16.7 MHz), which is a big reason why few DDS QRP rigs were
designed for 15m coverage.

The LC VFO makes a much better performing and cleaner K1, as long as it
has good stability.  The K1's LC VFO is amazingly stable.  Its continuous
tuning is far more natural and less fatiguing than the step incremental
tuning of a DDS rig like the KX1, IMHO.

I would NOT purchase a K1 that had been modified to use the output
of a DDS directly.

> Everything else remaining the same, because it is the perfect radio!

Well...let's just say it's the best QRP radio of its size and power
consumption.  Mine is almost 14 years old and I will never get rid of
it, unless someone sneaks in and changes it to DDS! :-)

> I have a KX3, but I miss my K1, should have kept it.

Exactly so.  I'll be ordering a KX3 soon...but my K1 stays forever!

73,
Mike / KK5F