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Old January 23rd 17, 07:16 AM posted to rec.radio.amateur.moderated,rec.radio.amateur.homebrew
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Default [N2HTT] A cootie?


73, de N2HTT

///////////////////////////////////////////
A cootie?

Posted: 22 Jan 2017 06:33 PM PST
https://n2htt.net/2017/01/22/a-cootie/


Settling in for the long winter season, I have lots of bench projects
waiting in the queue. Some have time constraints and are higher priority,
such as getting my HX-1681 back on the air in time for this years Novice
Rig Round-up (0000 UTC on FEB 18 through 2359 UTC on FEB 26, 2017). Others,
like finishing the one tube regen I started, or repairing half a dozen
broken items, will rise to the top of the list in due time. And there are
some new home brew ideas I am eager to start, definitely including another
QRP tube transmitter this year.

So with all these worthy items awaiting attention, how do I spend the
little bench time I had available over the last two weeks? I built a cootie
key, of course.
The Depot cootie key

A cootie key, or sideswiper as they are also called, is a key that is
operated with a horizontal motion of the hand, rather than the up-and-down
motion of a straight key. It has two contacts, left and right, and unlike a
paddle a key closure on either side closes the same circuit. Cooties go way
back; they were the first attempt to solve the problem of glass arm (what
we call a repetitive strain injury today) which was the frequent result of
too much straight key activity. It is said that the first cooties were made
by enterprising telegraphers who mounted two straight keys base to base on
their sides, with the keys wired in parallel. Later, commercially made
cooties appeared, touting less fatigue and faster keying speed as
advantages.

In the early 20th Century the bug or semi-automatic key made its commercial
debut. Since that key automatically completes the dits, the telegrapher
does less work, and soon the bug pretty much completely supplanted the
cootie key and they more-or-less disappeared. Today the advent of
inexpensive electronic keyers and the paddle, which uses two separate
circuits for the dot and dash, have pretty much relegated bugs and cooties
to the attic, to be used only by aficionados of retro and antique gear.

But there is one other group of hams who have traditionally embraced the
cootie: those seeking a key for next to no cash outlay. Cooties can be made
out of any piece of springy steel and two contact points. Hacksaw blades
are commonly used, but I have seen pictures of cooties made from steak
knives jammed point first into a block of wood! This is a technology that
lends itself to improvisation, and that is what ham radio is all about.

Sending with a cootie, or side-swiping, is tricky business. Basically, you
start each character on the same side of the key (Im right-handed, I start
with my right index finger first), and then alternate thumb and finger
creating the elements of the character. The timing is all on you, much as
it is with a straight key. I found the technique difficult at first, but
with some practice still find it difficult. My inclination is to start each
character with whatever finger was left over after completing the last, but
I can see that method quickly leads to disorganization and madness. The
always-start-on-the-same-side approach makes sense if you think about each
character as a separate unit, always formed the same way. Harder to learn,
but I think you get a better sounding result.

I have actually owned a very fancy cootie key for some time now, made by
Llaves Telegraphicas Artesanas (LTA) in Spain. The gentleman who made these
keys, Guillermo Janer, EA6YG, has been a silent key since 2008, but you can
still see a very nice page describing the keys he made at Morse Express.
LTA cootie, on a nice chunk of granite countertop

This key is beautifully crafted, but really awkward to use. With the pivot
in the center the throw is short, and the stiff brass arm has no give upon
making contact, making for a very jerky feel when keying. After several
tries to get used to it, I gave up and it sits very handsomely on the shelf
where I display my key collection.

I got interested in cooties again when just recently one came up for sale
on a club swapmeet listing. This was a cootie made by Vizkey. It gets
excellent reviews, and I got intrigued. The Vizkey version is based on the
venerable hacksaw blade which simultaneously provides the contacts and the
spring tension for the key. These keys are a bit pricey though, and I
wondered if there was a way to experiment with cooties that would require
less commitment.

On to steak knives and blocks of wood.. I researched inexpensive home brew
options, and came up with this really nice design by Mike Maynard, KC4ICY.
His Depot Key, so named because all the parts can be obtained from, well,
you know. Anyway it looked like a nice inexpensive way to play with a
cootie, and being based on a hacksaw blade I figured it would be pretty
much the authentic side-swiping experience. Mike estimates that his version
of the cootie can be built for about $10. I think the actual number is
closer to $20, but I didnt have any old hacksaw blades handy and the Depot
only had packages of two available. I did have most of the rest of the
hardware on hand, as well as the wooden base (leftover from the external
VXO project) and the wood finishing supplies (leftover from the Bayou
Jumper.) I bought the angle irons, the hacksaw blade, and the 1/8 stereo
plug which I was out of at the moment. And the buttons for the finger
pieces.

My first attempt at finger pieces was to cut out two rectangles from a
heavy polyethylene container. They looked awful, so I went searching
through the craft department of our local Wal-Mart, and found a package of
six really cheap coat buttons for $2. The buttons had flat backs so they
fit together nicely around the hacksaw blade, and a #6 bolt fit the hole
perfectly.
Coat button finger pieces

Construction was very straightforward. I cut the hacksaw blade to length
using a pair of tin snips (dont forget the safety goggles when working with
springy steel), and drilled a hole near the cut end to accommodate the
fingerpiece attachment. The blade was a little tough to drill, but no big
deal really, just go slow and perhaps use a drop of oil on the bit. I used
a wire brush in my Dremel tool to remove the paint from the hacksaw blade,
as it was a rather garish white and yellow color scheme.

In a departure from Mikes design, I added a bolt across the top of the
angles holding the contacts, so I would only have to wire one side. This
eliminates the possibility of using the key as a single lever paddle, but
adds some rigidity to the contact posts.
Strain relief

The only other feature I added was a staple and a dab of hot glue to act as
a strain relief for the cable, which is a short length of RG-174 coax. I
put a piece of non-skid foam backing, (the kind used under rugs) on the
underside, held in place with a few pieces of double-sided scotch tape.
Although key is very light, this arrangement holds it in place just fine,
and there is no need to hold the key with your other hand while keying.
Non-slip rug backing

So how does it play? Not bad, actually. The springiness of the blade, and
the soft landing with a little give on the contacts is very pleasant. It
makes a little noise when keying, but not nearly as bad as the LTA key,
which clanks dramatically with each stroke.

Ive been practicing off the air with it, and while I like the feel and the
side-to-side keying, I still sound pretty awful. There is a tendency to run
the dits together, and shorten the dahs. Based on internet advice, I set
the contacts pretty far apart this is supposed to help avoid the running
together.

There are many online resources for on the art of sideswipery the
SideSiperNet website lists nets and other information, and has a gallery of
keys posted by cootie afficianados that is very interesting to browse
through. You can also find a short essay on the practice of side-swiping at
Morse Express. The also feature anotherĀ*commercial cootie, the GHD-501 (see
the bottom of the page), a pricey but beautiful instrument.

I like my homely little cootie, and will continue to play with it maybe
even venture out onto the air someday if my sending with it ever becomes
comprehensible. I did get to satisfy my side-swiping itch without investing
in an expensive instrument dodged the bullet on that one.

73,

de N2HTT


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