I love it. It is great on many dimensions. Below I'll give my pros and cons briefly. The pros definitely outweigh the cons, despite the greater detail on the cons below.
I have tuned lots of wires, and also a Buddipole (usually used in vertical configurations with counterpoises). The KX3's ATU is great. I would suggest as long a wire as you can put up, as far away from metal as you can get, with a counterpoise of some kind. In May 2013 I put up about 70 ft of wire from my 2nd floor bedroom window out over a rooftop in a "vee" config. I added about a 15ft counterpoise going the other direction. The vee's max height is about 18-20ft at the peak and the counterpoise goes from the 10 ft window diagonally down to about 6 ft. The KX3 will tune this antenna 80-10M at under 1.3 SWR. The next evening I used that antenna and grabbed RK3ER with my 12 watt signal at 559 (CW).
For portable use I have this (external) 4S2P (4.6AH) LiFePO4 battery and charger:
I have ~2500mah Sanyo Eneloop XX cells in the radio. They hold charge very well (low self-discharge), will power the radio for a long time on receive, and will of course keep the real time clock running.
I also have a setup in my minivan that I use for "van portable": park the car, setup and operate (see below). I do this all the time, it's very quick and easy. Power comes from the car battery at 12.6V, which runs the radio at 10W maximum.
Small, light, allband/allmode - 160-6M, 2M coming; includes native support for digital modes.
Self contained: Just add antenna, power, and earbuds. (Oh yes, and a mic of course if you use SSB.)
Fantastic receiver, basically as good as you'll ever need. Great DSP filtering, NR, etc.
Stereo dual receive - beyond split or XIT, you can listen to the DX and to the chasers, simultaneously, one frequency in each ear.
Wonderful ergonomics (especially for a tiny radio - see below).
ATU will tune "anything".
SDR design, so you are able to attach a panadapter and even to do offboard signal processing if desired (though the internal DSP etc is great). [I haven't yet explored the I/Q or panadapter aspects but expect to this summer.]
Max 12W out and ability to ratchet power to any level.
The companion, external but highly integrated, 100W amp is now out and there is an internal 2M transverter board coming.
Quite nice integrated paddle (but see below.) Great QSK, CW memories, etc.
Elecraft and forum support community/knowledge/experience are top notch.
See the actual operating experience and ergonomics comments below. As a portable station (which I have done alot) it is just fantastic - again see the experience report below. I also use it at home quite a bit in fixed mode.
VFO encoder noise on higher bands. This is no longer
an issue. On July 8th 2013, Wayne Burdick announced that Elecraft
user-implementable modification to fix this problem (.pdf
file). The fix involves cutting three pins off a header on the
filter board, and it's not difficult at all. I implemented the fix
immediately and it took me about 10 minutes with static precautions,
etc. The difference is fantastic. In normal conditions the VFO noise
is gone on all bands 160-6 meters, without use of the VFO-NR or
RX-Shift compensations. To check under abnormal conditions, I
disconnected the antenna, and turned the RF and AF gain all the way
up. Under that condition, if the VFO noise is there, it is below the
receiver noise threshold and is inaudible on all bands 160-6 meters,
except for 10 meters. On 10 meters, VFO-NR takes it way down but it
is still audible. Further reduction on 10 meters can be achieved by
reducing the passband to ~300Hz with the DSP filter, to the point
where the VFO noise is virtually gone. But I emphasize that this (no
antenna) is really an abnormal condition, and with an antenna any VFO
noise is WAY below the noise on all bands.
No real time clock without the battery charger module. Why Elecraft didn't include a tiny button cell and clock logic in the base radio is a mystery to me. Having to carry around 8 cells just to get the time is foolish - see WG0AT's solution: a cheap watch attached to the top of the external paddle.
Battery charger: The battery charger is time-based not charge-based so you have to guess on the charge level of the battery and estimate time to charge at 200MA rate.
Cooling: I gather that for digital modes or AM (100% carrier modes) heating will be an issue and you have to reduce power e.g. to 3W - see all the alternative retrofit heatsinks that have emerged.
Connectors on the left side of the radio seem somewhat weak structurally, and there are many of them. You should have/get right-angle connectors to reduce lateral stress on these points, and there can be a bit of a wire tangle if everything is connected.
Pretty awkward disassembly/reassembly, e.g., to deal with batteries. You shouldn't have to do this very often but if/when you do, it can be awkward.
Thumbscrews that hold the stand-up rear feet keep loosening and need tightening often, their design isn't that great in my opinion.
Some like the Elecraft paddle and some don't. It takes some adjusting and there are some subtleties to having it make consistent contact. I did have a few issues, including most recently a kind of paddle "hiccups" - the rig seems to just "halt" or "interrupt" for a tiny interval in the middle of some dash or dot sequences, like it was adding a dah-length space or something. Another way to say it is that the rig with this paddle drops dits or dahs. I've now looked into this, and have made the modification found here:
(The intermittency is caused by the fact that the KXPD3 paddles are grounded through their moving joints, with no direct wired connection. This mod adds a thin wire from each paddle to ground, making a positive connection instead of a potentially intermittent one. It seems to have fixed my issue with intermittency.)
Overall the integrated nature of the paddle outweighs these, for me, in general. I also put 3M Dual-Lock on the right side of the rig and same on my Palm Mini-Paddle, attach the minipaddle to the KX3, and sometimes use that. Some pictures here, here and here show my version of the Palm attached at slight angle. A friend mounted his flush with the top of the KX3 as shown here and here (I like this a bit better). A minor disadvantage of the Palm might be the external cord from the paddle to the KX3 left side key jack (not shown). By the way. the Dual Lock is great stuff.
(Posted to the Yahoo KX3 list on 6/10/2013)
Monday evenings I take my son to his fencing club at about 23:30 UTC. Dropping him off, I drive my Honda minivan up the street to a small local park. A couple of years ago I had added a quick-release antenna mount to the roof rack, with a strap to the van's body, so the van itself is a counterpoise.
Tonight I got to the park, put a 16' MFJ whip on the mount (1/4 wave on 20M), and adjusted the whip for 1.3:1 SWR with my FG-01 (great little graphical antenna analyzer for the field BTW). I hooked up the KX3 to a cigarette lighter power plug (12V car battery), popped the antenna coax BNC onto the radio and switched it on with headphones. I was operating CW with the Elecraft KX3PD paddle. Setup time: about 8 minutes.
Over the next couple of hours I proceeded to work Baja California (DX, 10W), ME (QRP ragchew, 5W), then down the gray line again to AZ (QRP ragchew, 5W), TX (QRP ragchew, 5W), and Uruguay (DX, 10W) and then up over the pole to Russia (DX, 10W) - just one after the other, bang, bang, bang - with a whip on my van in an in-town park in central Illinois.
Why am I having so much fun? In a word, minimalism. Everything is so simple, quick and easy. A large part of it is the ergonomics of the KX3. Everything I need to do is right there on a button or a knob. Nothing gets in the way of finding stations, hearing them, and working them even in dynamic eveningtime band condx. I can slow down the keyer for a newer op; speed it up for a quick DX QSO; tighten the filter for a bit of QRM; RIT if someone's not right on frequency; CQ with a couple of messages, QSY up and down the band with the fast rate, draw out a weak signal with the slow rate, touch up the ATU, back off the RF gain for a 599 station, down the power for 'true QRP', up again for some DX punch, etc. etc. etc. The radio is TINY - just sitting on my lap - and all this is right there.
I cannot tell you how impressed I am with the KX3's ease of operation in the year I've had it (and I'm not even talking about its inherent capability). Tonight was an absolute BLAST.
Elecraft, thank you, thank you, thankyou.
I've now used this "van-portable" configuration about 5-6 more times and each time it's been wonderful. Last night I took my son out to Boy Scout Camp Drake in Fairmount, Il - he was drumming for an OA ceremony that night. I just parked the car in the Drake parking lot, popped the whip on the roof, made a quick eyeball length adjustment for 20M that checked fine with the FG-01, and off to the races. A bit later I retracted a few whip sections and moved up to 17M - this took 2 minutes with an FG-01 check. Later, same thing and up to 15M. Later, back down to 20M again. Overall: FG8, TG9, XE3, F5, W3, W4, W7, W0 - i.e., getting out all over the place, with QRP to 10W. Just before leaving, I even tried keeping the whip at its 20M length (~16 ft) and just used the KX3 ATU to couple that length on 30M (1:1 SWR, BTW) - I got N6's CA CQ on my first callback, RST 569, and had a nice CW ragchew.