Ultra-Portable CW Morse Code / Telegraph Key

BACKGROUND:

As an avid portable HF operator, regularly activating SOTA summits and parks for POTA, and an SKCC member, I wanted a fun little straight key to fit in the smallest possible kit. So I made one…

For portable ops, or to mount it to board for desktop operation, consider also printing the base as well.

Parts are kept to a minimum, and total cost per unit for a batch of 10 is less than $2 each ! At 53 x 23 x 10 mm (2 x 1 x 0.4 in.), this little guy won't take up much space in your pack, but provides adequate performance. Set screws allow independent adjustment of the throw and tension/resistance of the key. The 3.5mm TRS jack allows connection to your radio with any standard Aux cable.

Holes to press in three 4 mm magnets into the base of the key, and holes for 10mm magnets in the base plate/leg strap provide many options for mounting and use.

BILL OF MATERIALS:

Links are Amazon Affiliate links - It costs you nothing more, but I get a few cents on the dollar from Amazon if you purchase through these links.

Mandatory Items Qty Source

3d Printed 1 Piece Straight Key 1 Print it using the attached STL

3d Printed Base 1 Print it using the attached STL

3d Printed Case 1 Print it using the attached STL

3.5 mm TRS Panel Mount Jack 1 https://amzn.to/3Hadrd2

M3 x 4 mm Set Screw 3 https://amzn.to/3ir8Mca

M3 x 4 mm Machine Screw

(Alternate: Use one additional M3 x 4 Set Screw)

1 https://amzn.to/3uF4ZLb

30 ga Silicone Copper Wire

(Alternate: NiCr wire from my other iambic paddle builds, or other stranded wire 26 ga or smaller)

30 mm https://amzn.to/409le1s

PETG Filament ~20 g https://amzn.to/3H9QN4p

Additional/Optional

Aux Cable (4 ft) 1 https://amzn.to/3XZ1IUo

10 mm x 2 mm Magnets (for the base) 2 https://amzn.to/3VYIxIp

Silicone Rubber Pads 4 https://amzn.to/3LKvWa7

Leg Strap 1 https://amzn.to/40EgO2u

TOOLS:

- 3d Printer capable of printing PETG - 1.5 mm hex driver ( https://amzn.to/3gX4sB8 or https://amzn.to/3ulV3X1) - #1 Phillips head screwdriver ( https://amzn.to/3HaQlD2 ) - Tweezers ( https://amzn.to/3BaOeex ) - Wire cutters or scissors you aren't worried about damaging ( https://amzn.to/3VycZJK ) - Soldering iron ( optional - you can build the paddle without this ) ( https://amzn.to/3P3bxgk ) ASSEMBLY:

1.) Print all the things.

I've included the GCode I use on a Prusa i3 Mk ii if you want to just download and hit “print.”

Print your parts for the assembly. Use PETG only! This design relies on the flexibility and elastic deformation capability of PETG. PLA will not work.

Supports should not be necessary for any of the prints.

You may need to clean up the openings of the bottom holes on the base plate to get the magnets in if your first layer height results in some elephant's foot spreading.

2.) ( Optional ) Press the 4 mm magnets into the base.

CAUTION: Applying too much pressure to the top lever may break the key. Heat the holes with a heat gun or soldering iron briefly if they are too tight.

Place the 4 mm magnets on a flat magnetic surface. Align a bottom hole of the straight key frame to the 4 mm magnet and carefully press into place. Repeat for each hole and magnet.

3.) Attach a 50 mm (2 inch) piece of wire across both side lugs of the 3.5 mm jack.

Do not attach wire to the ground (center) lug. Use only 26 ga or smaller wire.

CAUTION: Do not overheat the lugs or it may damage the connector. Solder the wire to each of the short lugs.

If you don't have a soldering iron, twist the wire onto the lug, securing it through the hole and wrapping strand around the lugs. Try to make good electrical contact.

4.) Attach another 50 mm (2 inch) piece of wire to the long (ground) lug of the 3.5 mm jack.