[TenTec] Re: FYI - key click thread on Ten-Tec reflector

[Tom Rauch]

> I would just like to add that last weekend I listened a lot to
> the 160 meter CW contest.  Using the Rx340 filters even down to 100
> hertz, I found key clicks were all over the band.  It was easy to find
> places where there were no CW tones, but impossible to find places
> where there were no key clicks.  It seems as though most rigs now
> generate excessive clicks.

I think we have, through poor planning, made life miserable for CW 
ops on crowded bands.

Let's look at this in proper perspective:

I listen with a 440 Hz tone mostly. 

A 1.5 mS rise or fall time would occupy 0.66 of ONE audio cycle. 
There is absolutely no way anyone could recognize that as a tone. 
As a matter of fact a more proper and narrow bandwidth 5mS rise 
or fall would only be 2.2 cycles of the tone!! Our ears would still not 
sort that into a tone, instead it would sound like the brief burst of 
tone on WWV that marks each second (that we hear as a "tic").

We can not hear what happens in the first few cycles, other than 
hearing a "tic". We would have no idea if it is a tic from a switch 
being turned on, a click from a nasty rig up or down the band, or 
the start of a valid Morse tone. 

Even if we had magic ears that could actually hear the rise and fall 
(which none of us do), we have an additional problem. We LISTEN 
to that rise and fall through a CW filter! 

Our CW filter, assuming it is 500Hz wide, would never pass the 
significant sidebands of the 1.5mS rise and fall anyway!  This is 
especially true if the clicky 1.5mS rise or fall is not a gaussian or 
raised sine waveform. Since all that energy NEVER makes it to the 
headset and only serves to bother people up and down the band, 
why would we want a rig that transmits the wasted energy?

If you want to see how a proper waveform looks, just attach a 
scope to your receiver IF after the narrow filters and tune in almost 
any CW signal. The filter in your receiver will do all the envelope 
shaping, regardless of how nasty the transmitter is.

What you will find is a filtered rise-and-fall like the one I now use 
has an insignificant change in shape after passing through the 
receiver, but a nasty clicking rig is transformed to a nearly identical 
envelope shape!

The only difference is OFF the desired frequency, where it can 
bother others.

The rumor claiming weak signals are easier to copy with a rise and 
fall faster than 5mS is not true at all. There is no justification at all 
for having a rise and fall faster than 5 mS, or a shape other than a 
raised sine or gaussian shaped signal. You also can not possibly 
tell if the rise is raised sine or gaussian, or a clicky R/C filtered 
shape, one it goes through the receiver filters (unless you tune 
OFF the CW signal frequency).
73, Tom W8JI
W8JI@contesting.com