Introduction: Morse Key Paddles Iambic Type

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As a licensed Ham Radio operator, I always wanted to learn and practice Morse Code and going into CW sub-band.

As I got my Xiego G90, I thought it would be a good idea to explore QRP activities. Tried straight keys, but didn't work as smooth as Paddles or Iambic keys. Because I'm a DIY fan, didn't buy one but designed my own paddles instead.

Easy model to make using basic tools, and worked fine for 6 months now.

Xiegu G90 has a CW mode with its own Key connector at the back of the device (green connector- "key" label) where you can connect any straight or Iambic key. A 3-wires cable with the appropriated 3.5 mm connector was supplied with the G90. Attention!: always refer to the manual of your radio.

Electrical connections for Iambic keys are easy to set. Lay 3 wires: one for common signal, one for "Dits" and one for "Dahs". When Common cable is in contact with the "Dits" cable, a short tone is generated. When Common cable is in contact with the "Dahs" cable, a longer tone is generated. If maintained, G90 keeps generating tones.

This paddle allows you to operate "Dits" and "Dahs" with ease.

DISCLAIMER: I did this one especifically for the Xiegu G90 model. Your Ham Radio may not (and probably will not) use the same cable configuration. Always refer to theTechnical Book of your radio to operate Iambic CW mode and electric connections.

Always check with a multimeter BEFORE connect anything to your radio.

Happy QSOs!

73s from EA3HTH

Supplies

Materials:

Step 1: 3Dprinting

Download and 3Dprint the files from Thingiverse:

https://www.thingiverse.com/thing:5031571

No supports are needed, but rafts might be useful depending of the printer.

PLA works fine.

You might be interested in adjusting "horizontal expansion" parameter in your slicer, because paddles fits tightly to the body.

Step 2: Paddles in Place

Place paddles inside the Base piece. It's a tight fit because it helps to prevent from undesired movements.

Place 2x M3 screws in the top part of the body, going through the holes of the paddles, so they will only move in vertical axis.

These screws are not electrically connected.

Step 3: Screws and More Screws.

Place 2x M3 screws at both sides of the body. Three holes are provided. Try the closests to the paddles.

These screws allow adjusting the maximum sepparation of the paddles, and are not electrically connected.

At this point their lenght is not important.

Place 1x M5 screw and 1x M5 Nut at the hole placed at the center of the body
This screw is ellectrically connected to the Common signal of the 3.5mm jack.

Place 2x M3 screws at each Paddle throught the remaining hole.
These screws will be ellectrically connected to the "Dits" and "Dahs" of the 3.5mm jack. At this point their lenght does not matter, simply place them.

Step 4: Rubber or Magnet?

The paddles need some force to separate them when they are not operated.

I suggest using a rubber band to do so: Attach one end of rubber band to the screw of one paddle, pass it through the base of the body, and attach the other end to the screw at the opposite paddle (see picture).

Adjust tension using 2 rubber bands instead of 1, or using a longer one, or simply twisting it.

The other method I tested is placing 2x 8mm neodimium magnets at the holes at the internal side of each paddle.

Take into account that these magnets have to repell each other, so place one, and then place the second so the paddles tend to separate.

I tested both systems and found that magnets were way too powerful, so I recommend trying rubber band or smaller magnets.

Step 5: Electrical Connections.

Solder 3x 24 AWG wires to the 3.5 mm female jack.

Lay and connect the cable to the common signal to the central 5mm screw.

Lay and connect the cable of "Dits" to the screw of one of the paddles. Faston terminal might be usefull here.

Lay and connect the cable of "Dahs" to the screw of the opposite paddle.

This is valid only for the Xiegu G90. Other transmitters may have a different electrical connection. Always refer to your technical book.

Check with a multimeter that the connections are correct. Once you are completely sure this is correct, glue the 3.5mm jack to the base using hot glue, and connect it to your transmitter using an appropriated cable.

Step 6: Adjusting Screws and Operating

Turn the screws placed at the paddles (electrically connected) so they have a 2mm offset from the internal face of the paddle.

Turn one screw placed at the sides of the body clockwise until you hear a "Dit" or "Dah". At this point, turn 1/4 of a turn counterclockwise so they stop making contact. Repeat same step for the other screw.

You can play with the lengths of four screws according to the size of your hand or the gap between the paddles.

The smaller the gap between the M3 screws and the M5 screw, the more sensitive your key will be.

The more tension of the rubber band, less prone to errors but less speed operating the key.


Operating is really easy: I operate with the thumb and index fingers of one hand while holding the base with the other. Because of the size and the round corners, it is comfortable to hold.

Sometimes I place the key under the screen of the G90 because it improves its readability while holding the key in place.

Step 7: Improvements and Options.

Improvement 1: Try rounding the tip of the screws placed at the paddles so only a tiny contact is made with the M5 screw. Use a file or sandpaper to round it. The gap between them should be almost no visible.

Don't glue the screws: sometimes your hand will get tired and you will need to change the lenght of the screws, specially when operating for several hours. But once you get a comfortable configuration, little changes have to be made.

I usually keep the paddles extremely close, so I need almost no force to operate them and my hand and fingers don't get tired.

Improvement 2: if you will be using this key at your home or QTH, probably you will find useful operating with one hand only. In this case gluing the key to a heavy base is recommended. Place some adhesive feet to the base so it does not slip on the table.

My friend EB3FWC made me this one of half-transparent material. (Gràcies David!)