[CW] W0EB's Dot Stabilizer for Semi-Automatic Keys

Tue Aug 23 18:43:45 EDT 2022

Jim Sheldon, W0EB makes a very useful and interesting Dot Stabilizer. He
also discovered to many people's surprise that the cause of the dot jitter
was at the start of the dot, not the ending of the dot.  He has
oscilloscope traces to prove it.

I recommend all of Jim's Dot Stabilizers, I am a happy user, and I bought
several: one for my Vibroplex La Hiff Presentation, one for my Vibroplex
Original and Lightning Bug, one for my E.F. Johnson Speed-X bug, See
https://www.w0eb.com/DSmain.html

I first contacted Jim when he was active in the Eastern Mass (CW) net back
in the 1960s.

W0EB's Dot StabilizerFor Semi Automatic (Bug) Keys. Design Copyright (C) by
Aubrey J. Sheldon, W0EB 2014-2020, All Rights Reserved

Right handed Dot Stabilizer mounted on a late model Vibroplex Original
------------------------------
Back in the early 1930's, T.R. "Ted" McElroy (Morse copying World Champion,
set 75.2 WPM record on July 2, 1939) who also manufactured telegraph keys,
came up with a nice innovation he called his "Dot Stabilizer" This nifty
little gadget pre-loaded the vibrating dot contact spring by a very small
amount, effectively ensuring better dot weighting and came very close to
completely eliminating the very rapid contact bounce occuring when the
contacts wipe together as they "make" which creates what many call
"scratchy dot syndrome".

I was originally under the impression that this bounce was being caused by
excess dot contact vibration as the contact "break" occurred, but after
quite a bit of research and oscilloscope analysis by myself and one of my
users (pictures of the traces later on this page), I have finally realized
that it's caused mainly by improper contact alignment, minor imperfections
in the contact surfaces of both the fixed and movable dot contacts that do
not allow for near perfect mating of the two contacts as they come together
and the fact that the movable contact is actually on the end of a spring
that is really free to vibrate as the contacts come together during the
forming of the dots.

In a perfect world, the factory would achieve perfectly smooth surfaces and
perfectly square alignment of the two contacts, but we all know this is
really asking too much of them, and the average individual either doesn't
have the tools, expertise or patience to achieve this either. Mr. McElroy
evidently figured this out and came up with the original "Dot Stabilizer"
as he called it.

The DS stops the spring from bouncing too much as they come together at the
beginning of the dot. It allows setting this "make" tension at an exact and
adjustable point,and this comes very close to completely stopping that
"contact wiping" bounce which appears to be the root cause of "Scratchy Dot
Syndrome". It does not, however, correct bad CW caused by poor sending
habits or failure to keep the bug's contacts clean.

T.R.'s original version required replacing the existing dot contact
assembly with his stabilizer and fit only the McElroy manufactured keys.
For some unknown reason, most information on the original Dot Stabilizer
was either lost or ignored during the WW2 years and later except by a very
few people. I'm quite happy that I was able to resurrect something from the
past that does such a nice job of making a bug able to send better CW
without having to severely modify a nice key.

After accidentally rediscovering it a couple of years ago, I undertook a
slight redesign of McElroy's original device to eliminate the necessity for
replacing the vibrating dot contact assembly. This allows the device to be
easily installed and removed quickly with simple tools. I also came up with
a further variation on McElroy's design that can be used on even the "Flat
Pendulum" bugs such as the Vibroplex Lightning Bug, Military J-36, Zephyr
and Champion models as well as various copies of them and even the Japanese
Hi Mound "Coffin" bug.

I immediately copyrighted my own design and I currently hold the copyright
(C) for this design worldwide, all rights reserved. Anyone wishing to
manufacture these commercially or even for sale to clubs, etc MUST contact
me first and obtain written permission to do so. I have the right to refuse
to allow this and if this copyright is violated, I will pursue legal action.

I currently make "Dot Stabilizers" for the Vibroplex, Speed-X and McElroy
keys having the round pendulum and bugs with the flat pendulum, such as the
Vibroplex Lightning Bug, Zephyr, Champion and WW2 military J-36 bugs
(including the Lionel models) which are based on the Lightning Bug design.

I can also manufacture them for other bugs such as the European made
(metric sizes) bugs, etc. as long as you can supply me with the diameter
(round) or thickness (flat) of the pendulum and a sharply focused digital
photo of the actual bug you want it for. (I only need photos and pendulum
dimensions for bugs other than the McElroy and Vibroplex models.) They can
be made out of either aluminum or brass though aluminum is the preferred
material as it is far less expensive.

I did quit making them for the Japanese "coffin" bugs though as the
mechanism is located inside the "coffin" and with the close spacing of the
mechanical parts and contacts, it is VERY difficult (sometimes impossible)
to mount and adjust a Dot Stabilizer on one of those things. There is too
much chance of damaging something so please don't ask me to make one for a
"coffin" bug.

Now for something new. In early April 2019, I got a 3 dimensional (3D)
printer. After getting used to it and printing a myriad of things that
other people had designed, (files that were available on the internet for
free), I got the idea to try printing a dot stabilizer. Now, this wasn't as
easy as I thought it was going to be as I had no 3D model of the metal ones
I've been making for years now. I had to obtain and learn a 3D CAD program
(I chose Autodesk's Fusion 360). This turned out to be a pretty daunting
task but I finally found someone to help me get started and I was able to
draw out the various versions of the Dot Stabilizer to very exacting
dimensions to include the necessary holes, etc. A few test prints and
tweaks and I now have them for the McElroy bugs and both round and flat
pendulum Vibroplex bugs. The flat pendulum ones include the military J-36
as well. I put one on my 1963 Vibroplex "Original" (the test material I was
using was green in color) and have been running it ever since. I also sent
one to Don, WB6BEE for him to try on his McElroy bugs (he has quite a
collection of them). They are all working fine. They do distort a little in
the printing process and this is pretty much unavoidable due to the
materials used and the temperatures they are printed at but unless they are
examined real closely, this is usually not noticeable. It does NOT affect
the operation of the stabilizer in the least. The set screw holes still
have to be tapped and the "snubber" hook still needs to be made from piano
wire, but the use of the plastic printing material has allowed me to reduce
the cost by over $10 per stabilizer. Because of the shape of the wire hook
I cannot send them overseas without boxing them up and that puts a $13.50
to $14.50 USPS shipping cost on them so I'm not putting them on the
international market at this time. Due to shortages and discontinuations by
the manuafacturers, the "Tough PLA" I use can only be had in Silver.

In the photo below, I show examples of all three types. The left one is for
the Vibroplex round pendulum ones, Center is for the Vibroplex flat
pendulum and the right one is for the larger round pendulum of the McElroy
bugs after refining the sizes slightly for better fit.

*3D printed Dot Stabilizer bodies. As of June 01, 2020ONLY SILVER (as
shown) IS AVAILABLE*

*3D printed Dot Stabilizer (in black) on a McElroy key belonging toDon,
WB6BEE (photo courtesy WB6BEE).*

*Installation and ordering info for the standard and 3D printed models:*

They mount to the arm with a socket head set screw and the proper Allen
wrench is included along with a printed set of instructions explaining
installation and proper adjustment. Also, they are made entirely by hand so
there may be slight differences between each one (this won't affect the
operation at all).

The prices are $28.50 post paid for the aluminum and $38.50 for the brass
ones to domestic USA customers. Due to large shipping cost increases and
the extra, complicated Customs forms I need to fill out for export I can no
longer ship these internationally (unfortunately that includes Canada).

*Please email me W0EB. <w0eb at cox.net> before you order to check
availability.*

If you decide to order one or more, I will need the make/model of the
bug(s) you want stabilizers for and whether they are "left" or "right"
handed (the bug, not you). and in the case of the 3D printed ones, silver
is the only color available. Also, be sure to include your correct mailing
address as well. Due to pandemic restrictions, I can only accept payment
via PayPal to w0eb [at] cox dot net .

*__________________________________________________________________________________________________________*

Some additional images and information provided by a satisfied customer,
Fred Schebor, K8NGW after he installed a Dot Stabilizer I made for his left
handed Vibroplex Presentation. The following images are Copyright(C) Fred
Schebor, K8NGW and are used here by permission.

Left Hand Dot Stabilizer mounted on K8NGW's late model Vibroplex "Gold
Base" Original

Since I did not have a photo of a left handed bug with a left handed Dot
Stabilizer properly mounted on it to use in the instruction sheet I provide
with every dot stabilizer I make, Fred, K8NGW sent me pictures of the one
he installed on his Vibroplex Original (Gold Bug) Presentation model. He
also gave me permission to use the photo(s) as I needed and gave me a
copyright release to do so.

Fred also hooked up a scope and ran before and after tests of the keying
waveform using his bug. The first scope screen capture shows the contact
bounce that causes the "Scratchy Dots" and the second trace shows the
alleviation of the bounce that all but completely eliminates the
"Scratchies". Many thanks to Fred for providing these pictures and for his
kind permission to use them as I needed.

K8NGW Oscilloscope trace showing a "Scratchy Dot" before installation of
the Dot Stabilizer.

And, finally, the last picture shows the effect of an installed Dot
Stabilizer on the keyed dot, virtually eliminating the nasty bounce that
caused the "Scratchy" dot. I hope these photos and the accompanying
explanation helps illustrate the cause and one effective cure for a bug's
nemesis, the "Scratchy Dot Syndrome".

K8NGW Oscilloscope trace of a keyed dot after installation and proper
adjustment of the Dot Stabilizer.

Jim Sheldon - W0EB

w0eb at cox.net

For further information or to order one or more, contact Jim, W0EB.
<w0eb at cox.net>

Page copyright (c) 2019, 2020 W0EB, Images copyright (C) 2019, 2020 W0EB
and K8NGW (used with permission).

Vibroplex, McElroy, Johnson SpeedX, Lightning Bug, Champion, Hi Mound, etc.
are trademarks of their respective companies.

73

DR
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