Homebrew Straight Keys by WB9LPU

 Straight Keys in a Variety of Designs and Sizes

 

 

These PDF's show some attempts at straight key design and construction.

 

Two Straight Keys - PDF  (*)   These keys incorporate some design features found in European keys.

A Simple Straight Key Construction Project - PDF   (*)  This is a design that can be made with simple machine and hand tools.

A Marconi-Style Key - PDF    (*)   This key was made to recall the historic accomplishment of Marconi during the 100th anniversary in 2001. 

 

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      This was my first attempt at making a straight key (except for one made from a strap hinge when I was in the Boy Scouts).  It was constructed of aircraft aluminum (2024-T4) and has brass contacts.  The lever is pivoted by ball bearings at the far end of the key.  The "bridge" structure bears the screw that limits the upward travel, and the spring tension is set by the large wheel on the base.  The design proved simple to make and it works well, with a fairly light touch and adequate stability.  Its performance encouraged me to do some exploring of related designs.

     This is a group of four aluminum mini-keys for QRP operating.  From left to right, here are their features:  The largest of these is a ball-pivot model with spring tension and is fully adjustable.  The next key has the same mechanism, but scaled down for more portability.  Beside it is one of similar design that uses spring tension but has a vertical tensioning mechanism.  The last key is the prototype of the Parkwood Pup.  This key is the smallest of all - it has magnetic tensioning and is fully adjustable.  The lever is pivoted on ball bearings, and connection to the transmitter is made via an 1/8" phone jack.

  

     This is a brass version of the Parkwood Pup shown above.  While it is a bit heavier than the prototype, it still packs into a very small space.   Click here for more information.  


     This is an attempt at a more conventional design.  The mechanical parts are made from C360 brass with a lacquer finish.  It is mounted on a piece of Colorado alabaster (brought back from a quarry near Carbondale, CO).  The lever pivots on 1/2 inch ball bearings, and tension is provided by the usual coil spring near the skirted knob, which is turned from cocobolo wood.

 

 

 

 

 

 

 

 

 

 

 

 

 

      This small key was made to use up some odds and ends around the shop.  It was also an attempt to try a very light lever, made from Fortal aluminum and lightened by drilling a series of holes through it .  The result was a very responsive key with a vaguely Marconi look.  In that tradition, it uses a tension spring forward of the bearings.  It has my usual skirted knob, ball-bearing pivot,  and it is mounted on a piece of zircote wood.

      This key is an attempt to evoke the appearance of the early Marconi keys, with a historical twist.  My XYL and I visited St. John's Newfoundland on the anniversary of the first transatlantic transmission and stood on the very spot where the reception took place.  A kind local sculptor donated the white soapstone for the base; the stone comes from a local quarry that is no longer operating, so my remaining pieces are being carefully "hoarded."  For the full story, click here. 

      This key is similar to the one above, but it uses soapstone from Maine.  This is a darker material and is used, among other things, for wood stoves.  The knob is turned from cocobolo wood.

 

      Another key in the Marconi tradition.  As above, it uses 1/2" ball-bearing pivots.  The lower contact is shock-mounted to eliminate the "bounce" that sometimes occurs with massive keys when connected to a modern transmitter.  It still produces a satisfying "clunk" when it is keyed.

      Yet another version of the big key, this time built on a base of bloodwood and with a skirted knob of cocobolo wood.

     Still in the tradition of massive keys, this version is made of a high-strength aluminum alloy called Fortal.  It uses magentic tension (under the knob end of the lever) and pivots on 1/2" ball bearings.  The contacts are on the opposite end of the lever as in many maritime keys.  Fine adjustment of the contact spacing is by means of the vertical micrometer.  This key, and the one immediately below it, are more fully described in a PDF article.  (Click here)


     This key is another try at a front-contact key.  It is much smaller than the one above, but retains the same features.  It is made of Fortal and mounted on cocobolo wood.  The magnetic tension adjustment is below the knob end of the lever.  The large wheel next to the front contacts sets the travel distance.  While a bit lighter than the others, this key is both nimble and stable.  It is more fully described on the PDF file for the Fortal key above.


    To show that elaborate tooling is not necessary to make a smooth-working straight key, I developed simple design that can be build with the usual tools found in a home shop (it does require a small drill press, a hacksaw, and some files, along with some care and patience.)  All of the fittings are from local hardware stores or hamfest flea-market sources.  The pivot mechanism uses dome nuts that run in conical holes in the upright supports - it can be adjusted for free movement with no detectable side-play.   It uses a flat brass spring instead of a coil spring.   Complete instructions for building this key and its variations are given in a PDF article.  (click here) 


      Here are two more variations of the simple key.  The upper one uses metal parts of the same size as the previous key, but it is mounted on a longer and narrower base.  The smaller key has dimensions that are three-quarters of the others.  It is a nice size for QRP operation.