[Elecraft] Re-post from KX3 reflector (a Field Tester's review)

[Wayne Burdick]

Hi all,

Matt (W6NIA) posted this to the KX3 list. Since it's the first report  
on one of the current field-test KX3s, he and I thought it would be of  
interest here, as well. He included a photo, but of course that can't  
be posted to this list.

73,
Wayne
N6KR

* * *

Elecraft KX3: Field Tester Review of S/N 6
All-

Attached is a photo of KX3 #6 [actually not--see note above--WB].   
It's an outdoor shot with the backlight off.  This unit is in Field  
Test here, which is its own type of milestone for all those waiting  
patiently.  I'll be writing objective appraisals of this FT unit.   
That will be my intent, anyway (objectivity).  This email is a first  
cut.  Read on.


My personal opinion is that this is the coolest amateur transceiver  
ever designed, built, or dreamed of.  Perfect size, perfect weight,  
VERY respectable performance.  You can *really* take the KX3 with you,  
and you’ll really want to.  Mine’s going everywhere with me, including  
the workplace!  I know my engineering staff will demand to see how  
Wayne and crew fit it all in, and how well the KX3 works.


After one day using this unit, I've reached the conclusion that the  
KX3 is basically ready for initial production.  As is usual for a  
'young' rig from Elecraft, firmware is still a work in progress.  This  
should be no surprise to anyone on this list.  The hardware is at  
near-100% shape, IMHO.  There are a few minor issues - mostly features  
not yet implemented.  And I mean minor.  If I weren't an engineering  
manager in the consumer products industry I would not have noticed any  
of them.  The electronics seems solid, and I've done a bit of lab  
testing for MDS and selectivity.  Most of my testing has been on the  
air though.  My lab testing shows MDS better than -136 dBm, but my  
signal generator can't extend any lower.  No problems with rejecting  
out of band signals (away from the roofing filter's coverage).


On the air:  I've had about fifteen CW QSOs, using between 1 and 12  
Watts output power.  The antenna is a homebrew multi-band vertical,  
ground mounted.  Four of these Qs were on battery power.  No  
differences were found between operating on external and internal  
power, except for the output power limitations due to batteries.  One  
Q was with an extremely weak QRP station in New Mexico.  The APF  
helped with this, to the point that I could not have pulled him out  
without the feature.  With APF engaged, his signal was 539 with rapid  
fades to 319.  He was running 0.5W and I was running 3 W.  Great  
ragchew, with very few repeats.

Except for Navy-Marine Corps MARS, I'm mostly a CW op.  Several SSB  
contacts went successfully after a false start: I had to finagle the  
MH3's input connection a bit (a virgin socket seating issue).  I set  
the MIC and CMP values by listening on a second receiver and built in  
MONitor, giving  MIC=18 and CMP=10 as the best combination.  Audio  
reports using the MH3 and this setting were excellent - "clear as a  
bell" and "good presence”.  Output using the internal speaker is  
adequate, though not amazingly loud.  Some of that is probably my 55  
year old ears and too many rock concerts when I was younger.  The  
frequency response seems relatively flat and lows are surprisingly  
well-represented.  Distortion is low (< 2% THD the way I hear it).

The FOC and NA contests run this weekend were an interesting  
environment for first-time ops on the KX3.  Lots of strong signals,  
many in excess of S9+25.  A majority of the QSOs mentioned above were  
near strong signals and with the roofing filter in place I had pretty  
good luck ignoring the big guns while working weak signals.  I have to  
admit this is completely subjective, however years of experience with  
the K3 also tells me that the KX3 has similar characteristics in this  
regard.  The best example from on-air testing was the NM CW station I  
mentioned above.  His signal was marginal, meaning the APF was  
essential for pulling him out of the band noise.  At the same time, 3  
to 4 KHz up was one of those big guns thumping away.  I could even  
hear key clicks from the contester, but only a tiny amount of blocking  
from his signal on the KX3.  That's what I mean by "similar to the  
K3".  It's not identical though.  I found instances where a little bit  
of a strong station's signal was near- or in-band, and as you would  
expect some pretty severe blocking occurred.  I'd recommend everyone  
make sure they have the roofing filter on the "essentials" list for  
purchase.  In many ways the roofer makes the KX3 what it was meant to  
be.

One thing that’s notable and exceptional:  I haven’t seen any of the  
typical issues of a “zero IF” architecture.  No image problems, no  
ripple in the passband (in either SSB or CW), no audio artifacts.  The  
advantage to a zero IF architecture is that there’s no “donut hole”  
around the IF frequency; there are others too – one single conversion  
takes less space than multiple conversions, less power consumed, less  
heat generated.

As a Navy-Marine Corps MARS operator, I’m looking forward to using the  
KX3 in our ECOM exercises.  Its size and power consumption are perfect  
for such types of portable operation.  It’s the item that will take  
the least amount of space in your Go Kit.


Sorry so much of this is non-quantitative.  I'll try to get more out  
after another day or two.



Standard disclaimer:  I am not employed by nor do I have a fiduciary  
interest in Elecraft.



73,

Matt Zilmer, W6NIA / NNN0UET / NNN0GAF THREE
NMCM RMS Winmor: NNU9ET-5: Upland, CA.
mzilmer at ...