Most modern DSP transceivers exhibit a substantial delay between paddle
closure and CW sidetone. When running high-speed CW this delay disturbs the
human ear<>hand control circuit: the operator's experience says the key can
be released because the character is completed, but the ear says the key must
be held closed because the last element of the character has not been
finished or even started yet. We could call this situation the "delayed
sidetone dilemma". Most operators are not aware of the cause for the vague
feeling that something is wrong, the sidetone is somehow sluggish, long QSOs
are tiring and the errorr rate is high. To cut a long story short: CW is no
fun !
Steve Ellington, N4LQ, took up that subject in a recent posting on the tentec
reflector. He wrote: "I suppose the problem with using an old fashion RF
monitor on newer rigs would be with the big delay between actual paddle
closure and RF output. I know it would throw my little brain out of sync.
That's the problem I have with the Omni 6's sidetone. There's enough delay in
it to ruin my concentration at 40wpm. So I guess for high speed work, a fast
sidetone is in order ...". You hit the nail on the head, Steve !
At 40 wpm a dot is exactly 30mS long. In my Kenwood TS-870 for example the CW
sidetone is generated by one DSP and used directly to generate the RF signal
with a "calculated" phase-type SSB modulator in the other DSP. Advantage: the
signal really sounds exactly like the sidetone. Disadvantage: the measured
delay between keying and sidetone is 13mS. To make things even worse my
CMOS-Super-Keyer adds another 10mS delay and we end up with 23mS which equals
almost one dot lengt at 40 wpm ! In order to get rid at least of the delay
which is produced by the TS-870 I built an "outboard" sidetone. Result: the
fun is back !
Bottom line: Tentec, please give the ORION an undelayed CW sidetone which is
one absolute prerequisite for an outstanding CW transceiver !
73
Karl, DJ5IL
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