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Subject: [TenTec] Fwd: Re: GEORGE et al - QUESTION ON THE "HEAVY SIDETONE"
From: w5yr@att.net (George, W5YR)
Date: Sat, 02 Feb 2002 20:45:36 -0600
Tim, I guess that Steve and I and others are guilty of tossing around terms
that have a special meaning in the world of CW that might be different

"Heavy" as applied to keying means that the dot time is greater than the
space time, so the resulting code does not have the ideal 50% duty ratio or
1:1 time ratio. As a result, a string of dots will sound unbalanced and the
code in general will have a sound that over the years has become known as
"heavy." There just isn't the right amount of space/time between successive

On the other hand, if the dot time is much less than the space time, and
this is the Icom problem we have been discussing, then the dots sound
"light" and the code can be hard to read at higher speeds. That is a very
common problem with many bugs that you hear these days: the dot/space ratio
is way off and the dots sorta just peck their way along instead of being
good solid dot elements.

The reason for this problem in the Icom radios we have talked about is the
time lag that the radio imposes(when running QSK) from after the key
contacts close until the r-f output begins. In my PRO, that is 10 msec.
Now, if you just look at the sidetone signal on a scope and look at the
dot/space ratio of that signal, it is pretty close to 1:1. But, since the
actual r-f signal does not start until 10 msec later, the dots are that
much shorter than the space and the code sounds "light." The higher the
speed, the shorter are the dots and spaces because that 10 mssec lag
doesn't change with speed, so the dots get lighter and lighter as the speed

Now, if you change the dot/space ratio with an external keyer like the K3
or the computer program I posted about using as a keyer, then the result is
that the r-f output dots and spaces are correctly proportioned 1:1 and
sound "right." Icom does not provide making making weighting changes - they
only allow you to adjust the relative length of dashes compared to dots.
That is the "ratio" of the keying.

But, this leaves the sidetone dots now longer than the sidetone spaces, by
that 10 msec again, so the sidetone signal sounds "heavy" with the longer
dot times. This can be an unpleasant sound to copy and at higher speeds can
really be disturbing to some folks and hard to copy.

The solution to this, which Icom among most other JA radio makers tends to
ignore, is to provide for individually weighting the sidetone signal and
the actual r-f output signal. Of course, the real solution is for the radio
not to require 10 msec after the key contacts are closed to start making
r-f. But, it takes time to make the changeover from receive to transmit and
that time can only be made so small. Most of it is involved in certain
relays operating. And that changeover has to be made at the start of each
code dot or dash. So every code element is affected.

Your conclusion is therefore the correct one: if you want ideal code
weighting with your Icom, then you will have to rely upon an external
keyer, and even then unless that keyer provides for separate weightings of
the sidetone and the output signal, the sidetone is going to sound "heavy."

Such is life . . .

72/73/oo, George W5YR - the Yellow Rose of Texas         
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe   
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771
Icom IC-756PRO #02121  Kachina #91900556  IC-765 #02437

All outgoing email virus-checked by Norton Anti-Virus 2002

cyr999@extremezone.com wrote:
> The newbie is back hi hi. I think I missed something in this thread and need a
> recheck. Sounds to me like the net result is that any ICOM rig should work out
> just fine if you happen to already have a Logikey III external keyer and plan 
> to
> use it.
> The only part I'm not clear on is what exactly "overly heavy sidetone keying"
> means as used by Steve. Are we saying that the sound ouf our keying is overly
> loud compared to what we are receiving? And if so could not a resistor or so
> clear that up? Or...am I as ignorant as I suspect I might be hi hi. Thanks.
> 73/Tim

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