[K3] CW keying with Microham CW Keyer

[JohnK1JD]

Stewart, all

I have noticed the very same effect using the K3 with a Logikey K5. The first symptom is the sidetone which sounds like the code elements are being severely shortened. Accurate sending, especially at higher speeds depends a lot on the quality of the sidetone. Setting the K5 to 55% weight and compensation K=03 makes the sidetone tolerable but still not as pleasant as the internal keyer. Several folks on the air have given me subjective analyses of the transmit signal and the W=55/K=03 setting sounds better too, closer to the sound of the internal keyer. The latest test was performed yesterday at 40 WPM with DK4AN on the other end and no significant path distortion.

A whole other topic is sidetone 'timing jitter' which is much more noticeable on the K2 than the K3 and in either case especially at higher speeds. With the external K5 keyer, the sidetone timing is subjectively crisper than the internal keyer making QRQ sending easier. In past K2 discussions this has often been attributed to CPU multitasking.

A significant improvement to the K3 would involve addressing the use of external keyers so that both sidetone and transmit signal are faithful, well shaped reproductions of the the keyer output. A step further would be the incorporation of a dedicated keyer chip.

73, John K1JD
East Greenwich, RI


Folks,

I find the internal keyer of the K3 a joy to use but normally I find it more
convenient to use my Microham CW keyer as it gives CAT, and interfaces with
the contest loggers.

I have noticed however that with the Microham output plugged into the 'Key'
input at the rear of the K3 and all the keying settings in the router set to
default, that the elements are significantly shortened when observed on my
analogue scope; instead of a 1:1 dit to space ratio on a dit string it is
more like 40 to 60 or worse at a guess and the cw sounds decidedly choppy.

I can sort this my adding 10ms to the 'keying compensation' parameter in
Router; it then looks and sounds fine. I was just wondering if, and why this
should be the situation, particularly since the element timings look
absolutely fine when my key is plugged straight into the 'paddle' input on
the K3 and not via the Microham. Sorry I can't be more objective with
timings, difficult without a storage 'scope......

While observing the keying waveforms, I would say the leading edge looks
fine but the back edge has got a definite sharp transition which could do
with some smoothing; no sign of overshoot but it must sound hard judging by
the corner shape. Does anyone have any pix of keying waveforms for me to
compare...?

73,

Stewart Rolfe, GW0ETF  (K3 #145)
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