[Elecraft] Dilemma: K1 or KX1 - I can't decide

[Mike Morrow]

Doug wrote:

>I just can't seem to decide between the KX1 and the K1.

As far as RF performance only goes, the K1 is, IMHO, clearly superior.

(1)  The K1 uses an LC VFO that is cleaner than the direct digital synthesis 
frequency generation scheme of the KX1.  This reduces transmitter spurious 
output, and improves receiver performance because fewer spur frequencies are 
part of the local oscillator signal fed to the front-end mixer.  According to
reported measurements of the K1 with two-band board, it has better transmitter
spurious output specs than even the K2.  The low-pass filtering of the four-band
version is much better than the two-band version, so that's even better.

(2)  The K1 can be placed on any of the HF bands, though Elecraft currently 
sells parts for 80m through 15m only.  The KX1 DDS chip is clocked at its 
maximum rate of 50 MHz, which limits KX1 frequency coverage to around 20m and 
lower.  The 15m band is one of the best QRP bands when open.

(3)  The K1 IF uses a four-pole crystal filter, while the KX1 IF uses a three-pole
filter.

(4)  The K1's optional auto antenna tuner tunes a much wider range of impedances 
than that of the KX1.

(5)  Most find the continuous LC VFO tuning of the K1 to be more natural than 
the step-wise tuning of the DDS in the KX1.

(6)  The K1 has a noise blanker option, while the KX1 does not.

(7)  The K1 transmitter can produce up to seven watts of output power.  The KX1 
is about half that, if one is lucky.

(8)  The K1 case contains a speaker, the KX1 does not.  (The K1 has plenty of 
audio to drive it too.)

(9)  IMHO, the full-house K1 (with KNB1, KAT1, and four-band board) is easier
(less-tricky) to build than the full-house KX1 with all its options (40/20m with
80/30m option, KXAT1).

(10)  Personal preference...I like the front mounted controls of the K1 more 
than the top mounted controls of the KX1.

OTOH, the KX1 is clearly superior in terms of VFO stability. The DDS is about as 
stable as a crystal oscillator.  It is superior in its span of frequency coverage
within the limits of the DDS.  It can switch between USB and LSB due to
the frequency agility of the DDS as the local oscillator.  It has neat 
features like audio feedback to controls.  It is definitely smaller and lighter.

IMHO, the KX1 definitely has some positive features that the K1 doesn't have.
None of them, except VFO stability, are improvements in RF performance on the
ham CW bands.  Plus, the K1's LC VFO is amazingly stable.

But...if the K1 were not available, the KX1 would be my very next choice for a 
QRP rig.  It's a very fine and well-designed rig.  You really can't go wrong whatever
choice you make.

73,
Mike / KK5F