[WT-support] How to get clean fast CW out of a K3 without using CW QRQ mode

Bob Wilson, N6TV n6tv at arrl.net
Thu Nov 14 00:58:31 CET 2013

On Wed, Nov 13, 2013 at 2:22 PM, John Baranyi <n8um at comcast.net> wrote:

> Bob, what special handling does the K3 require w/WT 4.11?

The Elecraft K3 sends very poor (jittery) CW at speeds above 37 WPM, in
*both* semi-breakin and QSK modes.  This is a known issue based on certain
difficult engineering trade-offs.  It was the best way for Elecraft to keep
the K3 signal "clean" (compared to most radios).

Elecraft created a new feature called "CW QRQ" mode that eliminates this
jitter problem.  But if you use it, you have to turn RIT OFF (not just
cleared, but OFF), you cannot use SPLIT mode, and you cannot shift the IF
passband.  This is unacceptable to most high-speed contesters, who want to
use all of these features at the same time (especially RIT).

Only recently I discovered that if you close PTT IN, the K3 CW jitter
problems goes away, at all contest speeds, even if CW QRQ is OFF.  If you
use the internal Win-Test COM port or LPT port keying, Win-Test
automatically closes the PTT line for you, for the precise duration of the
CW message, and opens it immediately at the end.  This is 100% under the
control of Win-Test, and the CW timing is perfect.  However, it is
important to set the PTT LEAD time in the Win-Test SETUP menu to at least
10 ms.  0 ms does not work well.

Unlike all other radios (but Flex), the K3 has a "keying circuit" built in
to it's COM port.  You can use the same COM port for rig control, PTT, and
CW keying.  No other cables are required!  This is keying via fast on/off
signals, not via slow software commands (CAT or microHAM control protocol).

In the K3 menu, set CONFIG:PTT-KEY to RTS-DTR
In the Win-Test Interfaces Configuration Menu, for the radio's COM port,
set DTR=CW, RTS=PTT, Active With=Radio 1.
Set the PTT LEAD to 10 ms or more
 Set WinKey port to NONE (do not use WinKey except for hand keying)

You can also send CW via the standard KEY IN line, and PTT via PTT IN; you
don't have to use the COM port (e.g. the MK2R+ doesn't pass any of the CW /
PTT signals from the virtual COM port to the K3 serial port, so you have to
specify Radio = COM5, CW = COM5 (DTR), PTT=COM5 (RTS) in the Router "Ports"
tab to get it to work if you're not using LPT).

What about keying by hand?  Whether you use the internal keyer or an
external one, the jitter will only go away at high speeds *only* if you
close the PTT line manually, e.g. by closing a footswitch connected to PTT
IN, when you are transmitting by hand.  It is OK to enable VOX and semi
break-in modes to compensate for being early or late with the footswitch,
but the jitter problem will still be there when you're hand keying, *until* you
close the footswitch.

What if you want to use the WinKey?  First, why?  There is no compelling
reason to use a WinKey with Win-Test if you have a K3 (other than the
ability to adjust keying compensation, as described in my previous post).
 The internal K3 keyer is all that you need.  For SO2R, plug a paddle into
each radio for full control of each (and use the simple K3 Lockout
circuit<http://bit.ly/K3lockout> to
prevent simultaneous transmission).  Use the K3 Win-Test
Scripts<http://bit.ly/wtscripts> to
keep the K3 internal keyer speed in sync with the COM port keying speed (or
slower, your choice).

Yes, the WinKey has a PTT output line you can connect to the K3, and that
will prevent jitter problems while it is transmitting at high speed.  But
since Win-Test sends one character at a time to the WinKey, the WinKey
thinks it should open the PTT line after every letter is sent.  You can set
the PTT TAIL to a high value to prevent the PTT line from opening in the
middle of a message, but then you miss the first letter of the station who
answers your CQ.

In sum, don't use a WinKey, use the COM port or LPT port pins for PTT and
CW keying, and use the internal keyer or a standard keyer like a Logikey,
with a footswitch while hand keying, if you plan to operate > 37 WPM with a

Bob, N6TV
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