[Elecraft] Transmitter performance

[Dave]

I have recently received a copy of a publication known as DUBUS (for those 
outside of Europe, this is a technical publication dedicated to VHF, UHF and 
SHF equipment design and operating) and one particular article caught my 
eye.  The reason being that I'd suffered from some wide bandwidth signals 
from a semi-local beacon during a band opening on 23cm where the transmitted 
signal from the beacon could be detected over a large frequency spread.  The 
issue, in this case, was apparently down to the power supply used by the 
beacon.

Now, in the article in DUBUS 3/2013 (Vol 42) a description of potential 
problems for various Amateur radios from the quality of their transmissions 
was discussed and a table of 'good', 'reasonable' and 'poor' results from 
tests taken from ARRL and Sherwood Engineering data (which I know people 
from Elecraft are often more than happy to quote, so I would guess it passes 
some engineering muster...) were presented showing not only the receiver 
performance, but the transmitter performance as well.

Without wanting to quote the whole table (there may be copyright issues of 
course) but the K3 came top (distant cheering heard from Aptos, CA) but the 
KX3 came 6th.  The criteria for the ranking being a "TX Wide" measurement 
in -dBc and the K3 scored 128 at 100kHZz  or 120 at 360kHz - which only seemed to 
be included as two radios from a rival company were both ranked at the 
bottom of the table and could muster no better than a measurement in 300 and 
350kHz bandwidth) but the KX3 scored 107 at 100kHz.

The reason that this is important is that, in an area where people are 
tightly packed together, someone using a transmitter that generates 
significant wide band noise within a particular Amateur band is not the sort 
of neighbour that you want to have next to you on the VHF/UHF/SHF bands. 
You might be listening on, say 144.050MHz but if they are transmitting on, 
say, 144.350MHz then their wideband noise will affect you and, as is stated 
in the article, they may not even to be transmitting to generate significant 
signal levels.

So, to my question.  As I'm interested in VHF/UHF/SHF more than HF, why is 
the KX3 transmitter performance worse than the K3 and, other than selling 
the KX3 (which I'd prefer not to do) and buying a K3 (which is attractive, 
but financially a bit of a problem) what, if anything, can I do to improve 
the 'TX Wide' performance of my KX3?

Dave (G0DJA)