[CW] Stuttering Dots on Vibroplex - Info from Two Experts, Frank W7IS and Jim W0EB

[D.J.J. Ring, Jr.]

THE REAL REASON FOR SPEED KEY DOT STUTTER

The reason McElroy invented the dot stabilizer is all of the McElroy speed
keys suffer from self oscillation of the dot contact assembly.

What McElroy should have done was improve his dot contact assembly design
so that it didnt self oscillate rather than place a goofy metal arm onto
the U shaped dot contact assembly.

Take any McElroy key and place a magnifying light on the dot contact
assembly ... and watch what happens when you stop making dots.

In-between dots and after the dot contact comes to rest it will continue to
self oscillate.. which you will be able to plainly see with a 3 power
magnifying lens or light.

And its the serious self oscillation that causes dot stutter on McElroy
keys.

McElroys fix for the self oscillation was to place a metal brace on the dot
contact assembly to prevent the self oscillation.

But the metal arm can only just barely touch the long dot contact spring or
it will kill the dots.

So the adj of the metal arm is very very critical and will go out of
adjustment constantly.

I've tested hundreds of other speed keys of all different types and its
only the McElroy keys that have the self oscillation problem with the dot
contact assembly. What McElroy should have done was to redesign the dot
contact assembly so that it didnt go into self oscillation.

What's happening is users are becoming confused with what really causes dot
stutter and there are many reasons.

What works best to prevent self oscillation of the dot contact assembly is
to simply wrap dental floss around the U shaped dot contact assembly .. or
to place some thin foam behind the U shaped dot contact assembly and hold
the foam in place with dental floss.

Below are the real causes of dot stutter:

1. Using too much return coil spring tension for the dot arm. Which causes
the dot arm to hit the damper with too much force.. which can and will
cause dot stutter.

2. If the damper is adjusted wrong--- it will also cause dot stutter.

3. The idea is to use minimum force necessary for the dot side coil spring
tension and then adjust the damper for best dampening (which will help
prevent dot stutter)

4. The spacing of the dot contact to the dot post can also be adjusted for
least amount of dot stutter.

5. If your key has an articulated damper assembly-- (rather than a simple
dampening ring).. then what I do is lock the articulated damper in place by
placing fish line or dental floss around it. And then all the dampening
will take place on the dampening wheel. And that articulated damper wont
fly up in the air .. which causes dot stutter as it comes back to rest.

6. Something else that helps dampen the round dot arm keys is to place a 3"
long 1/4" diameter trombone speed control on the round dot arm keys. The
larger diameter of the 1/4" hollow trombone provides better dampening on
the damper wheel.

7. And lastly and most important--- if all the piece parts on the key are
not perfectly lined up... it can and will cause dot stutter. And that's
because if all the piece parts are not perfectly lined up.. it will
unbalance the key and make it difficult to send with due to the dot stutter.

I hope this helps settle the dot stutter issue problem once and for all.

Try placing a magnifying lens on your "U" shaped dot contact assembly to
see if it self oscillates when coming to rest or in-between making dots.

If you see the self oscillation, then wrap dental floss around the U shaped
contact assembly per the above info.

73 de Frank W7IS

Jim W0EB has more info on his "Dot Stabilizer" here:
https://www.w0eb.com/DSmain.html

They help greatly in getting rid of scratchy dots.

73,

DR
N1EA
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/cw/attachments/20200707/fcda72f6/attachment-0001.html>