A CW Concerto: Piano-Style Paddles for Backpacking
Special to The ARS Sojourner
Several articles and comments on piano-style paddles sparked an idea why not apply this design to miniature, lightweight paddles? I could see several advantages. First, a thin, flat assembly would be more rugged than conventional paddles. Second, the downward keying motion would tend to anchor the unit in place, instead of pushing it around. This would free up my other hand for tuning, etc.
A first attempt at such a set of paddles was built in time for last summer's Sierra Nevada hike and the Flight of the Bumblebees. I wrote about that trip and my experiences with the prototype paddles in "A Sierra in the Sierra," ARS Sojourner, October 2000. A few shortcomings in the design became apparent on that hike. I built a new set after the trip and have since used them on a couple of short field trips, including activating Humphrey's Peak (Arizona's highest summit).
The paddles are built from double-sided, copper-clad board. The base should extend at least half an inch around the ends of the paddles so that downward keying motion will tend to keep the paddles in place, rather than tip them over. (My prototype was too small.) I attached small, adhesive rubber feet to the bottom of the base, as close to the corners as I could get. The feet make the paddle more stable on slightly uneven surfaces, such as rock slabs.
I used a small file to smooth all edges of the PC board parts before assembly.
More details are apparent in the close-up photo. I found that the paddles needed to be 1/4-inch wide in order to flex enough for easy keying. You can notch the sides with a file to soften the keying even more. The ends of the paddles are 1/2-inch square to fit my fingers comfortably. Four PC board spacers, two under the rear of each paddle, create the necessary gap for the paddle contacts. I also needed one paper spacer to get the exact spacing I wanted. Each paddle is mounted with two flathead machine screws and nuts- the holes on the underside of the base are countersunk for the screw heads. Contact spacing is adjusted by slightly tightening or loosening the two screws. This seems to be a very stable arrangement, since contact spacing doesn't change even after the paddles have been banging around in my pack for a day.
I soldered a pair of old relay contacts to the underside of the paddles and to the top of the base. (The bare copper of the PC board tarnishes and doesn't provide reliable keying.) A pair of black, flat rubber feet on the top of the paddles provide a non-slip keying surface.
Before assembling the paddles, I used a triangular file to carefully cut through the copper on the underside of each paddle arm, just forward of the spacer. The dit and dah wires are soldered to the undersides just forward of the cut, and the common wire is soldered to the base. As you can see in the photo, I also tied the 3-conductor ribbon cable in a knot and passed it through a hole in the base as a strain relief.
Here's a shot of the paddles in action on Humphreys Peak. The paddles are resting on the top of the Elecraft K2, but any flat surface works. I've used rock slabs, the bottom of a cook pot, and paperback books. The two-fingered keying style does take getting used to, but with practice it becomes natural.
PARTS LIST
1 2x3" piece double-sided, copper-clad board
4 flat-head brass machine screws and nuts, 6-32 x 1/2"
4 old relay contacts
4 rubber bumpers for base
2 rubber bumpers, flat, for paddles
1 18" length of 3-conductor ribbon cable
1 plug to match keyer jack
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Bruce Grubbs, N7CEE, has been active in QRP for the last fifteen years, and enjoys homebrewing, kit building, and field contesting. His favorite wilderness activity is exploring the Grand Canyon on trips of a week or more, and he also enjoys long backpack trips in the mountains of the west.