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I’m the proud father of
two Elecraft radios: K2 #1770
born in 2000 and K3 #2887
born in April 2009. I
really ought to give them
proper names.
I
built both radios from the
kits, partly to save a few $
but mostly because I enjoy
making things. Like
Heathkit years before, the
Elecraft kits are excellent,
providing detailed
step-by-step instructions,
all hardware and electronic
bits (solder-it-yourself
components for the K2,
pre-soldered surface mount
PCB modules for the K3), and
if needed responsive online
support from Elecraft’s
chief engineers plus the
community of builders and
fans. Both radios
worked first time and are a
joy to use. The thrill
of hearing the first
callsigns on a receiver
you’ve just finished is
hard to beat - actually
working DX with a homebrew
transceiver is superb.
These are not
beginners’ projects
though. The K2 took me
a month of evenings to build
and the K3 an intensive
day. Learn to solder
properly before you try building the K2!
Quick links
- The K2 suitcase set
- The K3, a serious radio for serious contesters, DXers and DXpeditioners
- Useful K3 features
- K3 wishlist and bugs
My K2 #1770
Both my Elecraft radios are physically compact and lightweight. The K2 is about the size of a car
radio. The K3 is about the size of a large box file, similar to other mid-sized ham transceivers but
smaller than the FT1000 etc. Pelican waterproof cases or aluminium flight cases with foam inserts
are a good way to protect them both when travelling, and are small enough to travel as hand
baggage ...
This QRP ‘suitcase set’ consists of the K2, some antenna wire and string, a Palm mini paddle, pen and
paper, and a small switched-mode PSU to recharge the rig’s internal 12V SLA battery, carefully
packed into the foam insert and ready to go in an emergency (living on a major fault line in one of
the world’s most active earthquake zones, that’s no joke). As well as in the shack on decent
antennas, I’ve used the K2 portable stylie on picnics and holidays in France, Brussels, and New
Plymouth feeding wires thrown over convenient lighthouses etc. The auto-ATU will tune almost
anything but wire dipoles and verticals make more efficient antennas than random wet strings.
My K3 #2887
The K3 is more sophisticated than the K2 with a fully digital IF and AF using DSP for demodulation,
noise reduction, AGC etc. Mine has the second receiver option (allowing SO2V at last if not SO2R!).
I can monitor the beacons and CW end of 10m simultaneously. It is handy to be able to listen to
split callers in a pileup (in one ear) while also listening to the DX station (in the other ear).
The K3 has a true diversity mode with two independent receivers, phase locked by sharing a
common reference oscillator. Using a 30m fullwave loop on the subRX in my right ear and the beam,
vertical or dipoles on the main RX feeding my left ear, I find diversity mode is worth about 3dB due to
the loop partially filling-in QSB dips on the main antennas. Signals sway from side to side in my head,
floating across the gap between my ears (no comments please).
Whereas the K2 covers the main 9 shortwave bands 160-10m, the K3 also covers 60m and 6m,
with an optional internal 2m transverter also now available.
The K3 is not perfect however, and is more of an ongoing project that a finished radio. Check out
the spectrum anomalies on this BeaconSee output for example: the horizontal white and pinkish lines
are most likely artifacts of the K3’s DSP:
By comparison, the following screenshot from my TS850 shows no such obvious artifacts:
There are already K3 mods and add-ons:
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Improve the LF audio response into headphones. The original 10uF AF coupling capacitors near
the headphone jack can usefully be increased to 100 or better still 330uF to avoid excessive LF
attenuation, but be careful to avoid stressing and lifting the solder pads. (Note: increased bass
may not be to everyone’s liking).
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Alex UR5LAM suggests mods to the IF buffer amp too - details are unclear at this point but he
has published photos of the mods and comparative audio spectra showing 2-tone IMD
improvements: plot of K3/100 before mods shows a rather poor signal. After the hardware
mods, the signal is much improved. With the latest firmware’s improved AGC as well, the final
result is looking even better still.
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UR5LAM also suggests adding a 1uF capacitor to the LF amplifier chip to reduce the annoying
turn-on thumps and cracks - again I’m uncertain about the details as a photo is all we have to
go on.
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Solve a nasty transmit spur on K3s released in mid-2009 by removing a capacitor.
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Rather than constantly reaching over to the rig or adding some sort of external switch box for
the 5 DVR/CW memory buttons (M1-M4 plus the REC button used to interrupt sending), a third
party utility called K-Keys lets me define function keys on the computer keyboard. Cool!
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From Elecraft, there’s the P3 panadapter to watch signals across a band segment, and a 500W
solid state PA in the works.
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Others? Let me know!
Useful K3 features
I’m discovering new features of the K3 all the time ...
Triggering the K3’s voice memories from N1MM contest logger
If you have the K3 DVR option installed, N1MM’s superb contest logger software can be configured to
trigger the K3’s voice memories using the PC’s function keys to send the relevant K3 commands:
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In N1MM, open the SSB memory config screen (Config --> Change CW/SSB/Digital Message
Buttons --> Change SSB Buttons).
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In the .WAV File column, instead of the file name of a .wav file on the PC, enter the appropriate
K3 command string to play the relevant memory:
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The four “CATA1ASC” commands shown in this screenshot play the K3’s voice memories M1
through M4 using function keys F1 through F4 respectively. You can send other commands to
the K3 in the same manner - check the K3 Programmers Guide for the available commands and
parameters.
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Click OK to save the config.
Test it at this stage if you wish by hitting F1 to F4 in N1MM (assuming you have already recorded
messages on the K3). Note: it’s best to put the K3 into TEST mode to avoid actually transmitting
the messages on air until you are ready to work people!
Now configure the radio port to send PTT commands: this will allow you to interrupt the memory
currently being sent with the PC’s ESCape key - dead handy if you press the play button just as
someone comes back to you:
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Go to the port config (Config --> Configure Ports, Telnet Address, Other)
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Identify the COM port you use to control the K3 from N1MM and click the SET button for that
port.
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Turn on “Radio PTT via command” by putting a checkmark in the box.
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Click OK to come out of the config menus.
“Instant CW split” 
A handy way of instantly dropping the K3 straight into split mode in a pileup is to use the K3’s fancy
new switch macro facility. It avoids the need to press a whole set of buttons in the correct sequence
when the DX is calling “up 1” (or whatever) and the adrenalin is flowing fast. Here’s the instant CW
split macro I am currently using, with an explanation of each of the macro commands below:
SWT13;SWT13;UPB4;FT1;DV0;SB1;RT0;XT0;LK1;BW0060;BW$0270;MN111;MP001;MN255;
1 2 3 4 5 6 7 8 9 10 11 -----------12----------
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A>B [first time] copies the frequency from VFO A to VFO B, assuming I have found the DX on
VFO A and have nothing in particular on VFO B
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A>B [again] copies the mode (and other params?) from A to B
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Moves VFO B up by 1 kHz (4 is one of the set values - see the programmers’ guide for other
possible split values) - note: +1 is just a common starting value!
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Turns split on - this is the very step I sometimes forget when doing this lot manually!!
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Turns diversity mode off
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Turns SubRX on to listen on my split TX frequency in the pileup on VFO B, while still listening to
the DX on A (useful to find the exact calling spot)
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Turns RIT off in case it was set
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Turns XIT off in case it was set
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Locks VFO A so I can still move VFO B to find the best TX spot in the pileup to call but if I knock
VFO A by mistake, I won’t lose the DX frequency
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Tightens the filter on VFO A to 600Hz to cut down QRM on the DX frequency
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Opens the filter on VFO B to 2.7kHz to listen for successful callers in the pileup
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Mixes audio from VFO A (the DX) in both ears with VFO B (my TX frequency in the pileup) in my
right ear only [MN111 is the code for the audio mix function; MP001 is a parameter; MN255
ends the code]
I have configured this sequence on the M3-hold macro key, in other words if I find some juicy CW DX
operating split, I just press and hold the M3 key to run the macro and set me up in split, transmitting
one up, listening on both the DX and my TX frequencies with the filters all set. Fantastic feature!
I'm tempted also to turn the subRX preamp off and maybe turn its attenuator on to reduce the
subRX audio and QRM from the pileup, using PA0$;RA1$; but meanwhile I simply use the AF/SUB
knob to reduce the volume of VFO B relative to A.
Please note: these macros are still evolving as I try new things! If you have better ideas to share,
please let me know or share them with the Elecraft mailing list.
“Instant CW pileup”
I have programmed another macro key to do the converse of the “instant split”, enabling me to
instantly start listening ‘up 1’ when I get a CW pileup going and need to split. In this case, I use the
main VFO A to tune around the pileup, transmitting on a locked VFO B. The commands for that are:
SWT13;SWT13;UP4;FT1;DV0;SB1;RT0;XT0;LK$1;BW0270;BW$0060;MN111;MP002;MN255;
1 2 3 4 5 6 7 8 9 10 11 -----------12----------
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A>B [first time] copies the frequency from VFO A to VFO B
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A>B [again] copies the mode (and other params?) from A to B
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Moves VFO A up by 1 kHz (4 is one of the set values - see the programmers’ guide for other
possible split values) - note: +1 is just a common starting value! I normally tune from there.
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Turns split on
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Turns diversity mode off
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Turns SubRX on to keep an ear on my TX frequency, while also listening to the pileup
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Turns RIT off
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Turns XIT off
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Locks VFO B, allowing me to tune through the pileup on VFO A without the risk of accidentally
knocking my TX frequency on VFO B
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Opens the filter on VFO A to 2.7kHz to catch callers who are not right on my announced split
freq (I can always narrow the bandwidth on A using the width control if the pileup gets too big,
but mostly I prefer to pick out individual callers ‘by ear’)
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Narrows the filter on VFO B to 600Hz to avoid hearing split callers too close to my TX freq,
while still listening for those who fail to split or cops who QRM my TX freq
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Mixes audio from VFO A (the pileup) in both ears and from VFO B (my TX freq) on the right ear
only
“Unsplit”
Having used either of the above split macros, I wanted a further macro to reset the K3 quickly to my
normal operating setup:
FT0; LK0; LK$0; SWT13; BW0270; DV1;
1 2 3 4 5 6
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Turn off split
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Unlock VFO A
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Unlock VFO B
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Copy the VFO A frequency to VFO B
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Set VFO A to 2.7kHz bandwidth
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Turn on diversity mode which sets VFO B to the same filter settings as A and automatically puts
VFO A audio in my left ear using the main antenna and the subRX on my right ear using the
receive antenna
Other K3 features and tips
If, like me, you use Logger32 with the K3 and if, also like me, you prefer to use the K3 in CW-REV
mode rather than CW, there’s a simple workaround to get the K3 to stay in CW-REV when you click
on a DXcluster spot - see my Logger32 page for details, also how to get Logger32’s DVK function to
trigger the K3’s DVR memories.
 If you also have a K3, check out the nifty K3-EZ program from
N2BC. Like Elecraft’s own K3 Utility program, it communicates
with the rig, checking its configuration and allowing you to modify
settings more easily on your PC than through the setup menus.
Nice job!
Another useful little program is K-Keys which sends K3 (or indeed
K2) command macros from the PC using function keys. I use it
to command the K3’s DVR, triggering the CW and voice memories
without having to reach for the front of the rig. K-Keys was
written by Ken, KE3C, for the VE2DXY Zone 2 contesting team,
and is beggar-ware (they ask for a $10 donation to the VE2DXY
club - fair enough).
K-Keys sends its commands via the serial port, which in my case
is a cheap USB-serial adapter from BY via Dick Smith Electronics.
Since Logger32 or N1MM or MMTTY or K3 Utility also need to talk
to the K3 at the same time, I use LP-Bridge by N8LP to share the
serial connection amongst all these programs.
Here's a tip for AFSK RTTY users on the K3. The tones transmitted by the PC should match the
tones expected by the K3, particularly if you have the TX audit filters turned on (it’s a menu option).
If they don't, the PC audio will trip the VOX but little if any RF will emerge and the K3
sidetone/monitor will be quiet or silent. I discovered this when changing to a new sound card. I'm
now using a second card to separate PC bleeps, MP3s, YouTube audio etc. from RTTY tones. While
playing with the settings, I discovered the PITCH setting in AFSK modes on the K3. The low tones
(915Hz) sound nicer to my CW-tuned ear than the default high tones (2125Hz), so I set the K3 to
915. I neglected to change the MMTTY setting - largely because I tend to use "NET" in MMTTY to set
the transmitted tones to match the received tones, which lets me 'tune' on RTTY just by clicking in
the middle of RTTY sigs on the MMTTY waterfall (I hope my convoluted description makes sense!).
With NET off, MMTTY defaults to high tones which the K3's line input evidently filters out (although
the VOX presumably triggers on raw audio before the filter).
So, it seems NET in MMTTY is probably not a good idea with the K3 which expects tones to match its
setting, within some margin-for-error anyway (not much with the RTTY transmit filter option set). I'll
just have to tune the receiver to match the tones that MMTTY sends without NET, and set those
tones to 915Hz. Having set the 915Hz tones in MMTTY, I saved the MMTTY profile to stop it
reverting to the high tones every time MMTTY is re-started (same applies when using MMTTY within
Logger32: set the tones then save the profile).
According to someone on the Elecraft reflector, the K3’s numerous birdies can be significantly
reduced if not eliminated by carefully dressing the cables within the case, knocking out the remainder
using the clever LO displacement function in firmware. With a quiet receiving location, birdies on the
high bands are the most annoying so perhaps I should give that a try, next time I have the case
open.
My K3 wish-list & bugs
The K3’s firmware is amazing in what it can do but inevitably there are a few little bugs and flaws.
Here’s my current wish list:
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I often use a footswitch to hold the PTT closed during an over, mostly to stop the amplifier
dropping out. If I release the PTT footswith while sending CW (relying on VOX to continue
holding the PTT) or even if I turn on the PTT while the rig is already sending on VOX, the K3
sometimes messes up the character being sent and occasionally latches on the keytone on the
rig. PTT handling should really be a lower priority than CW sending ...;
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Curiously, while the K3 happily lets me send CW while in SSB mode, it refuses to do so if I assert the PTT line;
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Fast tuning is a pain: even with two speed control buttons (fine and rate) and using the clarifier
as a fast-tune knob, it is awkward to get between, say, the 10m beacon sub-band and CW or
SSB sections. “Ballistic tuning” is on the cards, apparently, meaning that the tune rate increases
with the rate of spin of the VFO knob/s. Meanwhile I am using the RIT/XIT encoder knob to
move more quickly, and now also to set the VFO to round kHz values;
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I’m finding it hard to learn to use the appropriate memory store or recall buttons, so I
sometimes overwrite a memory by mistake (it might help if the V--> M button was red - I’ve
coloured mine with a marker pen until I learn to be more careful!);
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There is no quick memo function like on the TS850, FT1000 and others. That’s a really useful
way to store the current settings, whizz off to check something out, and return to where I left
off. A single button-press was mostly all it took, or I could tune between 5 quick memo stores
using a knob [I’m now using M4 as a temporary memory. Not quite as easy or flexible as a
true quick memo function but good enough for now.];
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The internal keyer allows messages to be repeated but the repeat delay can only be set from
the config menu. Since the main VFO and sub VFO knobs are locked out during TX, it would be
handy to be able to adjust the delay with one of these, while still sending ...
The best thing about Elecraft, though, is that I can whine about all the above directly to the guys who
write the firmware, and I’m reasonably confident they will address the bugs and perhaps add more
features in time, as they have already done. Other software defined radios are also updated from
time to time but users appear to have little say in what changes are made by the manufacturers.
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