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Author Topic: What Is Responsible For Generating The 'Feel' Of A CW Key ?  (Read 718 times)
WB5AGF
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Posts: 12




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« on: September 09, 2014, 05:27:23 PM »

This is a topic that has been bubbling-around-in-my-head for a long while but it is still so 'fuzzy' that I am not even sure how to describe .... but I will make an attempt.

What is it that gives a CW key its 'feel' ? I'm talking about the sensation you get when you tap on one key and it feels 'dead' and yet another key has a subtle, but quite noticable (and frequently pleasant) sensation through the finger tips.

In trying to analyze the difference (between a 'dead' and a 'live' key) I have noticed that usually a 'dead' key's contacts are simply that .... two contacts that get whacked together when the key is pressed. They are normally mounted directly on the underlying actuating pieces of the key (the 'rocker-arm' of a straight key and the base).

A 'live' key, on the other hand, frequently has had an effort made to allow for some slight 'vibration' of the contacts when they are pressed together (several keys that I have been reviewing have their contacts sub-mounted on small pieces of springy material instead of being directly on the underlying 'rocker-arm' and key base). One (interesting) exception to this is the large Kent 'pump' key that I bought at Dayton about 20 years ago. I got the key on the metal base (not the wooden one) and although there is no 'springy' contact involved .... when this 'pump' key is pressed your fingertips get an immediate (and somewhat disconcerting) sensation that appears to be the reflected compression wave travelling back through the 'rocker-arm' from the metal base. If the tightening screws, that hold the mechanism tightly to the metal base, are loosened every-so-slightly then this 'compression wave' goes away. I have fiddled with one of the wooden base versions of the Kent 'pump' key and it does not exhibit this characteristic (I presume that the less mechanically resonant wood base does not 'ring' like the metal base does).

I've recently bought a little straight key with no visible markings but I suspect (from the look and materials used) that its an eastern European military key. The interesting thing about it is that there is a slight amount of 'kickback' to the fingers when the key is pressed and the only thing that I can figure is that the relatively thin metal 'rocker arm' oscillates infinitessimally when it comes into contact with what's limiting its motion (the contacts when being depressed and the 'stop' when lifting up on the handle).

The German Junker Key has a good feel and I don't know why. (Why?) The British WT8 key, that I bought for 25 cents in 1964, feels fine for a simple straight key (I believe that the 'rocker-arm' 'rings' slightly from shock excitation caused by the contacts impacting).

Why am I wondering about this (you may ask) ? One reason is that I have a few keys that I like the looks of but which feel 'dead' to my fingers (and I'd like to 'wake-them-up').

Remember LTA Keys (from the Balearic Islands) from a few years back ? (They went out-of-business when the owner, EA6YG, became a Silent Key in 2008.) I have several of their CW keys and, although they're pretty to look at, their 'feel' leaves much to be desired (the 'GMM cootie key' needs to be completely reworked).

Thoughts ?    Feedback ?

- Paul, WB5AGF
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WX7G
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« Reply #1 on: September 09, 2014, 07:39:16 PM »

I agree that hand keys that close abruptly have a hard and unpleasant feel. Some give as the contacts close is that I like. I've seen (felt) this enhanced by using a thin, springy wooden base with four very short rubber feet. This produced a bit of give as the contacts hit home.
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N6GND
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« Reply #2 on: September 10, 2014, 09:35:52 AM »

I agree that hand keys that close abruptly have a hard and unpleasant feel. Some give as the contacts close is that I like. I've seen (felt) this enhanced by using a thin, springy wooden base with four very short rubber feet. This produced a bit of give as the contacts hit home.

I agree. Long-lever Swedish type keys like the Amplidan which are very well-liked by straight key enthusiasts manage to damp out the vibrations produced by contact closure. The damping is affected by the length and cross-section of the lever, the type of metal used (for example brass or steel), the way the lever is mounted (bearing rigidity) and the mounting of the contacts (on a springy piece of metal in the Swedish types).

As you point out damping can also occur in the base mounting of the key. An example is the Junker which has a very solid feel.

I also think sending style makes a big difference in how one perceives the feel of a key. American style sending with the forearm resting on the table implies lower physical effort using smaller forearm muscles and smaller contact openings with lower spring settings. Euro style sending implies more effort using larger muscles of the upper arm in a more energetic approach.
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KB1WSY
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« Reply #3 on: September 10, 2014, 05:56:30 PM »

Try this: turn off the sidetone, and use the key "deaf."

Under those circumstances what normally feels like a good key can feel terrible ... and vice-versa.

Not sure what that proves!

73 de Martin, KB1WSY
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WB5AGF
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« Reply #4 on: September 12, 2014, 09:09:51 AM »


Friday Morning
12 Sep 2014


Something that I believe is probably a related (to how a CW key 'feels') topic ... That being the effort IBM went through when creating the Selectric II Typewriter.

I read (long ago) that IBM did a fair amount of research on how touch-typists liked their typewriter's keyboards to feel as the keys were struck.

Who was it ? .... Who(m?) was it ? ..... There was a computer years ago that had a keyboard with what were commonly referred to as 'chiclet' keys. They were little pieces of plastic that felt 'dead' (i.e. no tactile feedback) when struck.

I need to build a 'test jig' .... a simple straight key with the contact surfaces mounted on 'ears' that will allow me to play with trying out resilient (slightly springy) materials and see how that affects the 'feel' when the key is depressed.

- Paul, WB5AGF
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KH2G
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« Reply #5 on: September 12, 2014, 11:07:36 AM »

Magnetics like in the Bencher paddles can give a world of variety. I think it is all in the individual prejudices (Not meant in a negative sense)
Regards, Dick KH2G
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GW3OQK
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Posts: 145




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« Reply #6 on: September 13, 2014, 06:10:20 AM »

Paul, what you are doing is interesting, for I have thought about my choice of key.

For me I want no springiness whatsoever in my keys. What I like are solid unbending keys like the Kent, WT8amp and Marconi 365. I fix them to the bench so there's no possibility of movement or vibration.

Sending Euro style is all I know. I experience no strain. Any flexibility is in my fingers and wrist. WSY mentioned turning off sidetone, and I now realise I always move my headphones so I can clearly hear the solid clicking of the front and back contacts, so its sound is all part of its "feel.
 
When I was a young RO I could send at error free at 28 on the WT8amp but now I can only do about 23. I have no wish to use anything but a straight key for speed is not important to me, its sending and receiving perfect morse that counts.

73, Andrew
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W1JKA
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« Reply #7 on: September 13, 2014, 06:32:58 AM »

To me the responsibility lies in the amount of spring return tension of my straight key.
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WB5AGF
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« Reply #8 on: September 14, 2014, 10:38:35 PM »


( It must be a lack of sleep .... the mind wanders.)

O my ducats! O my daughter! O for 'Morsum Magnificat'

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KB1WSY
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Posts: 770




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« Reply #9 on: September 15, 2014, 08:30:52 AM »


( It must be a lack of sleep .... the mind wanders.)

O my ducats! O my daughter! O for 'Morsum Magnificat'



O tempora, o Morses!

73 de Martin, KB1WSY
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