A NorCal Project ...
by Wayne McFee, NB6M
The best part about these paddles is that you can make them yourself in just a couple of hours or so, start to finish. They are made from readily available materials, and cost almost nothing to build.
All that is required are some scraps of double sided PC board material, a piece of single sided PC board material for the base, measuring 1 7/16" by 2", two optional phono jacks, two short pieces of hookup wire, four 4-40 brass nuts, and two 4-40 by 1/2" long brass screws. One more 4-40 brass screw, one inch long, is used to position the adjustment screw supports for soldering, and is then put back in the junk box.
The base could be made out of double sided PC board, if you want. The phono jacks are optional, because you could very well just solder the wires of the connecting three wire cable directly to the paddle set, which is what I did when I made my first one of these.
To get an idea of what you are building, have a look at the drawings. You will see that the whole setup is very simple. The rear frame, paddle, and two adjustment screw supports are all made out of double sided PC board material.
The tools you will need are: Hack saw (just the blade will do), file for rounding and smoothing edges, a small hand (or electric) drill and appropriate bits, and a low wattage soldering iron and solder. For enlarging the tension adjustment hole in the paddle, you can use a tapered reamer (available from Radio Shack) or a small rat-tailed file.
Using the drawings as a guide, first cut out and shape the five parts made from PC board material. Note that it will be far easier to drill the holes for phono jacks in the rear frame, the initial hole for tension adjustment in the paddle, and the holes for the adjustment screws BEFORE cutting the relatively small pieces from the board. First, outline their shapes in the material, drill the appropriate holes, and then cut the pieces from the board.
Then, use the file to round corners and smooth the edges of the pieces.
As noted, I soldered one 4-40 brass nut to one side of each of the adjustment screw supports, in order to provide the threads for the screws to fit into. You could simply drill and tap (with a 4-40 tap) the PC board material and use just the lock nuts. However, in the interest of strength and durability, I recommend soldering a nut to each support.
Note that the copper foil is cut in two places on each side of the paddle. This can be done with either the edge of a small file or with the hack saw. Cut just enough to be sure you have seperated the copper foil nicely. What you are doing is creating the switch contact pads for the Dit and Dah side of the paddle. It is necessary to cut the foil in two places on each side of the paddle, as shown in the drawings, so that static electricity and other stray electrical currents from your skin won't cause erratic keying.
The tension adjustment hole in the paddle is enlarged (thereby removing material from the paddle itself) to provide whatever paddle spring tension you desire. This is done before the phono jacks and connecting wires to the switch pads are installed, and AFTER the paddle set itself is soldered together and the adjustment screws are installed and adjusted for whatever switch gap feels good to you. So, initially, cut about a 1/8" hole.
The assembly procedure is as follows:
First, set the rear frame in place, centered and about a quarter inch in from one end of the base, and tack solder one lower edge of the rear frame to the base. Check visually for proper placement and that the rear frame is perpendicular to the base. Heat the solder tack, move the rear frame as necessary with a finger, and let the solder tack cool. Then tack the other side before running a bead of solder all along each lower side of the rear frame.
When you are running a bead of solder between two surfaces which are at 90 degree angles, the trick is to prop the unit up so that the two surfaces form a V, with the apex at the bottom and the two sides about 45 degrees from the vertical. This way, the melted solder will run quite nicely along both sides of the joint, and form a very strong and nice looking connection.
Next, solder one 4-40 nut to one side of each adjustment screw support. The trick to doing this is to screw the nut onto a screw, put the end of the screw through the hole in the support, rest the support in a horizontal position, heat the nut and its adjoining copper foil, and wick the solder underneath the nut. Once the nut has been soldered in place, and the unit has cooled, simply unscrew the screw from the nut, and do the same operation on the other support.
Then, position the two adjustment screw supports on the paddle base, and solder them into place. The trick to positioning them is to screw the one inch long 4-40 brass screw through both supports, leaving about a 3/8" space between the two soldered on nuts, which should be on the inside of each support, facing each other. Use the paddle as a guide to how far away from the rear frame to position the supports. The front edge of the supports should be about even with the foil cuts seperating the touched portion of the paddle from the switch pads. The far end of the paddle, with the tension hole in it, will butt up against the rear frame, and, AFTER the adjustment screw supports are soldered in place and the one inch screw removed, it will be installed permanently.
The adjustment screw supports should be soldered along both lower sides of each support. Again, tack solder one side, then the other, and then run a bead of solder along the lower edge of each. this will insure that they don't move during the soldering process.
Next, remove the one inch screw from the adjustment screw supports, install the two lock nuts, one on each screw, running the lock nuts right up to the screw heads, and screw the adjustment screws into their respective supports. Leave enough space between the two to fit the paddle between them.
Place the paddle in position between the two adjustment screws and butted up against the rear frame. The lower edge of the paddle should be at least 1/16" above the surface of the base.
Finger tighten the two adjustment screws against the paddle, which will hold the paddle pretty well in position while you then tack solder each side of the paddle against the rear frame and then run a bead of solder along the edge of each side of the paddle where it butts against the rear frame.
Now, loosen the two adjustment screws slightly, and adjust them for whatever switch gap feels good to you. Tighten the lock nuts to maintain that gap.
Before installing the two phono jacks and the two short pieces of hookup wire that connect from the center of each to their respective switch pads, open up the tension hole as desired, removing material a little at a time, until you have whatever paddle spring tension feels good to you. Remember that you can always remove more material. It is hard to put it back.
When you have the paddle spring tension set to your liking, install the two phono jacks, and solder the two short pieces of hookup wire to the center connections of each and to their respective switch pads. Remember to leave a small amount of slack in each wire so that the paddle can move easily.
You will need a three wire cable (or two shielded audio cables with a stereo miniature phone plug installed on one end and two phono plugs on the other) to run from the paddle set to your keyer or rig. I used a pair of shielded audio cables, cut the phono plugs from one end of each and installed a stereo miniature phone plug, soldering the shield of each audio cable to the ground connection of the plug, one center wire to the ring connection and one to the tip connection of the plug.
Before you install the stereo plug, cut several short (3/16") lengths of the outer insulation from some scrap RG-58 (or 59 or whatever you have) and slip these over the two audio cables, spacing them about every three inches. Makes great cable ties and looks good also, with black audio cables.
That's all there is to it. You now have a very portable small, light, and best of all, cheap set of paddles.
I operate them by either holding the paddle set in the palm of one hand and operating the paddle with the thumb and forefinger of the other, or by holding the paddle set down on a tabletop with my middle finger placed over the junction of paddle and rear frame, and the tip of my forefinger placed next to the adjustment screw support on the near side of the paddle frame, which leaves plenty of room to operate the paddle with the thumb and forefinger of the other hand.
Download NB6M's Paddle Files Here
As a QRP enthusiast and home brewer I often surf the web for small and easy to build paddles or interesting schematics. I found the article from NB6M on the Norcal page.
Although I normally use a Bencher BY-1 iambic paddle, the construction of this key was so easy that I immediately decided to build one because the BY-1 is too expensive to use during field work.
I used some double-sided printed circuit board, fret saw and file to construct the paddle within 2 hours. Dimensions are as given by NB6M. I didn't use plugs but soldered 3 pieces of wire to test and adjust the paddle. Screws 4-40 are not(?) available in the Netherlands so I used metric M3 screws.
I noticed that there is a difference in the resistance you feel while moving the lever to the DOT or the DASH side, especially when the contact space is minimal and the finger pressure is low. This is caused by the tension in the solder at the fixing point of the lever.
I'm not used to single-lever paddles, so the cw code was not faultless during my first QSO. I placed a rubber nut on each side of the lever to make it feel better.
Using this type of construction as a foundation I'll make a double-lever paddle.
Adjustment of the contact-distance in relation to the tension in the material when using this design (both contacts are between the two levers!) is the bottleneck up to now.
73 de Carel, PA0CMU
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by The American QRP Club, Inc.
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Page last updated: May 22, 2004
The American QRP Club (TM) website is Copyright 2003
by The American QRP Club, Inc.