[CW] Iambic contact gap settings

[David J. Ring, Jr.]

Actually the "close spacing" is a critical adjustment of three things:

1.)    Minimum contact spacing so that the contact does NOT false.
2.)    Lever throw.
3.)    Vertical play and horizontal play of the pivot of the key.

If the levers were arranged so that a very small movement of the lever made
a huge movement of the contacts, most people would say that the key is
adjusted for close spacing.

Unfortunately, the mechanical tollerances and size of the key are the
limiting factors!

More precise tollerances and avoidance of wiggle in any direction, lack of
"stickiness" in the bearing (or lack of one) will enable the contact spacing
to be minimized.  If there is too much play, the contacts won't align
consistantly, which will mean that sometimes they will contact, and
sometimes they won't for a given movement.  If the ability of the pivot to
move is not consistant, or is restricted, the lever won't move freely and
consistantly.

A longer lever from the finger piece to the fulcrum of the key will enable a
more sensitive throw - It is easier to close the gap with a certain pressure
applied.  The mass of the key also changes the way the key behaves.

I am not a mechincal engineer, but I know there is relationship to key mass
on the lever.  Large lever keys "seem" easier to use and to have closer
contacts, however one key with a very short lever - the WBL V22L - has
perhaps the best touch for high speed.  The lever is so small.  But I guess
if you consider the whole paddle in determining the lever size, the lever is
very long on the fulcrum to the paddle as opposed to the fulcrum to the
contact points.

The mass of the lever in this key is very tiny - just a small right angle
shaped piece of steel.

73

David Ring
N1EA




----- Original Message -----
From: "Bill Brannick" <wmlb@sbcglobal.net>
To: "Ken Lotts" <ken@lotts.net>; <cw@mailman.qth.net>
Sent: Wednesday, November 19, 2003 1:54 PM
Subject: Re: [CW] Iambic contact gap settings


> At 04:22 11/19/2003, Ken Lotts wrote:
> >.  but now I am wondering how many
> >old timers set their contacts (on their iambic paddles) out a ways..  As
a
> >side note, I suspect the overall paddle design might have a lot to do
with
> >how far the gap setting might end up at because of lever action (paddle
arm
> >travel).
>
> I had a Bencher for a number of years before switching to one of  K8RA's
> fine keys.
> Perhaps some would call it too close, but I have always used a single
> plastic coated playing card to set the gap.  Obviously far less then
1/16".
>
> Bill, W6WLB
>
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