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

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

Hi Joe,

You  said:

> If you have a wider dot bar
> swing, ie. slower speed ranges, you will have a stronger contact with
> the damper, over travel.   It the steady state, the weight bar should
>
> just contact the damper. The damper only effects to dot bar's stop,
> not the dot spring contact.


What you call the dot bar, I think many people call the vibrator. I
think you're saying "At rest" the weighted vibrator bar should just
contact the damper. Also it's not the frequency of the pendulum that's
the important thing, excepting that faster sending operators try to
minimize the swing of the vibrator bar to minimize "turn around time"
(going from dot to dash)

, and that's the problem I see.

I agree 100% with that.

> I have to wonder why you are concerned about what a contact is
> doing in the open position?  When a contact swings to the closed
> position, you have to be concerned with two things.  Contact over
> travel and contact wiping.

I'm sorry you must have misunderstood me, I'm not at all concerned
with what the dot contact is doing in the open position. It is not
doing anything! It is the contacting of the dot contact on the U
shaped dot contact spring and the dot contact at the end of an
adjustable machine screw on top of a pillar which elevates the
adjustable dot contacting machine screw to the correct height that I'm
concerned with.

> If there is no over travel, it is susceptible to light contact, poor or
> no wiping and possible scratchiness.  When the contacts separate,
> it should wipe open.  Once clear, there is no effect on the next
> contact closure.

You have the problem.

> There are simple basic adjustments for bugs and if properly used, they work
> without stuttering. They need to used vigorously, but with proper good rubber
> feet will not move about on a smooth flat surface.

People don't understand that you need a vigorous action to wipe the
contacts clean and to compress the dot contact U shaped spring which
determines the "dwell" of the contact closure (dot length) and being a
pendulum acton where the dot spring pushes away from the dot contact
post, determines as well the dot spring which is (thankfully) equal to
the dot length.

Rubber feet that are soft, really help the bug not move, Blu-Tack sold
at business supply and general hardware stores is useful if your
rubber feet are hardened and won't hold the desktop.

The late G3HGE, Tom Withers developed a dual lever semi-automatic key,
it was beautifully made but Tom's design goal was to have a bug that
could be used at tight spacings, that is small pendulum swings, and
light action on the finger pieces.  I disliked the keying from this
bug, also it was to difficult for me to use because I'm used to the
old fashioned - but correct - wider spacing, and more vigorous
pendulum swing and dot contacts "crashing" together making a beautiful
crisp dot.

73
DR
N1EA