CW ops - please check your keying!

[K8AC]

In the recent 10 meter contest and this weekend's Stew Perry event on 160, I noticed a high number of signals with truncated dits.  In some cases, it was bad enough to require a repeat of a call or exchange, especially when the signals were weak or QRN was high.  I recorded a few signals in both contests and noticed that in those cases it was the leading dit after an inter-character space that was being shortened.  The dits in question ranged from about 25% to 50% too short.  With today's rigs, what you hear in your sidetone monitor isn't always the same as what is being transmitted, so it's a good idea to listen or look closely at your CW waveforms to see if you have a problem there.  You'll need a separate receiver to do this - don't just look at your sidetone. 

The technique I use is to record the signal using a waveform editor (Adobe Audition in my case) and then zooming in on a code segment to compare the length of dits to spaces and dahs.  An editor will allow you to measure the element lengths precisely.  If you notice a problem, see if it's there in both semi and full break-in modes.  You can also use this method to spot key click problems by observing the rise time and shape of the leading edge of the envelopes (trailing edges as well). 

Thus far, the three stations that I've recorded with the problem have all been using K3s, but other high-end rigs are known to have similar problems.

73, Floyd - K8AC

[NI0C]

Floyd,

Thanks for pointing out this potential problem.  I don't think I have it, though I do operate a K3 and the second letter of my call sign would be susceptible to truncation of "the leading dit after an inter-character space."   (I've listened carefully to my signal in a second receiver). 

I wonder what would cause such a problem?  Perhaps it is the rig's internal keyer, or someone's QSK setup.  I use an external keyer.

It is, of course,  much more common to have the leading dit or dah of a transmission to be clipped  (caused by "hot keying" an amplifier relay).

73,
Chuck  NI0C

 

[N3QE]

Many modern rigs have a large number of menus for setting timing details related to CW keying. I think there's some justification for these especially when it comes to keying an external amp.

Similar to how on SSB there are a bunch of menu items for audio spectrum goofing and processing. Again there's some justification for these.

For both CW and SSB, the parameters can often be tweaked to yield a signal that's really not copyable.

When hooked to a computer with a contest logger doing the keying, that may also be trying to work the PTT as well as the CW line, the permutations of possible goof-ups becomes infinite.

Creeping featuritis is not a new phenomena in ham radio or any other sphere. e.g. keying vs amp relay timing problems are hardly new and they seem to bite contesters worst.

[K8AC]

There are a few possibilities, but the three cases I looked at were very accomplished CW operators with a lot of experience.  I doubt that any or all of them would be exposed to the simple causes.  If I had the problem, I'd begin by comparing internal vs. external keyers, and QSK vs. non-QSK modes without an amplifier involved.  I know that many prefer QSK mode in contests, but I also believe that many who are using QSK in contests do so because they were told it's the best thing to do.  Of course, you can suffer from a short first dit even in non-QSK mode.  

73, Floyd