[Elecraft] OT: optical sensor paddles

[Ron D'Eau Claire]

Gee, Ed, that's not my experience with bugs (been using 'em for 30 of
the last 50 years on the air). 

I've put my rigs on a scope a few times and haven't detected any "make"
bounce, nor does it makes sense to me to expect any.

When the dot contacts "make" they are really SMASHED together by the
weight of the pendulum coming over. The dit contacts slam together and
get pressed harder and harder while the kinetic energy of the pendulum
gets stored up in the hairpin spring on the moving dot contact. Then the
combination of the spring at the base of the pendulum and the force of
the hairpin spring on the contacts combine to reverse the pendulum's
direction and push it away to end the dot.

The self-resonant frequency of the hairpin spring is low enough that
during the "rebound it is releasing the energy stored on the "make" and
pushing the dit contacts tightly together as it shoves the pendulum away
until the hairpin reaches the end of its travel, then it reverses
direction and actually separates the dot contacts at a speed far faster
than the pendulum is moving - at least for a fraction of a mm or so.
That's enough that at normal keying speeds it should not be able to
touch the contacts again as it vibrates. 

In that way a properly adjusted key will have the hairpin and pendulum
springs always working together to slam and hold dit contacts together
or to very quickly pull them apart. 

I've heard a lot of ops "slur" their dots by releasing the paddle too
soon and thereby releasing the pressure on the mechanism before the
springs have reversed direction and opened the contacts. That makes the
last dit short and sometimes messy-sounding because the springs haven't
had a chance to finish their motion. But that's the challenge of using a
bug properly - ya' have to know when the dit ends and MOVE that paddle
at the right millisecond. The operator has to provide precise timing...
none of the loosy-goosy "let the logic put in the right space and finish
the dit or dah" that a keyer allows. 

That's the challenge that has always kept me using a bug, even though I
have spent lots of hours on keyers over the years. 

The problem with conventional bugs that I've run into in recent years
(okay the DECADES... since solid state became common) is that there
usually is not enough current flowing to keep the contacts clean and
slightly dirty contacts can give lots of low-level logic the fits. I
keep a bit of rough card stock handy to burnish mine often. The optical
sensors in the GHD keys are supposed to eliminate that, but the GHD keys
also have a warning NOT to use them in direct sunlight! (However one
buddy who is using one said that his seems to work okay with the direct
sun shining on it!). 

Ron AC7AC
K2 # 1289

-----Original Message-----

Basically Tim, there is always a snappy keying signal associated with
bugs 
(the contact-bounce on 'make')....
73 Ed Tanton N4XY <n4xy@earthlink.net>