TELEGRAPH KEY

I've always had a keen interest in the mechanics of speed keys and how they evolved.  I only collected speed keys to learn about their mechanics.   What follows is a summary of the many years of testing and learning about speed keys.   And what makes these speed demons tick.   During the testing process,  I came up with a  better way to slow down the dots on speed keys.    I call it the Extendadot.  Which is described in detail here and later in the journal.  

This summary of ideas for fine tuning your speed key is a work in progress.   I'll probably make updates to the procedure as time goes on.   I've fine tuned hundreds of speed keys and I can go through the process fairly quick.   But when I first started, it would take me days of frustration --- when I just couldn’t find the right combination of settings to produce good code. All keys are slightly different so it’s a matter of finding the keys "Sweet Spot"--- where code seems to roll off the finger pieces.    I hope this helps others to get the job done quickly --with a minimum of fussing around. 

If you found a speed key from the early nineteen hundreds, it was probably dirty and all beat up.   Most of the keys from that era eventually end up at estate sales.   After they have been stored in a musty basement for a half century, there can be rust and a heavy coating of dirt and grime.    The key parts can be removed and cleaned in an hour or two.  

Then all the parts on the key need to be lined up so that they are in perfect alignment and balance.  If you don’t have all the parts lined up perfectly, you will never be able to fine tune it for perfect code.     The key can’t be used until the rust and corrosion is removed from the straps on the bottom.   And the only way to do that is to remove the dot and dash contact posts as well as the contact posts for the keying wires.  Cleaning the corrosion off the screw heads and on the straps where the screw heads join up to the straps.   With the contact posts off the key, its then easier to clean the top painted surface with mineral oil using cotton balls and Q tips.   Mineral oil works really well to renew the paint surface without damaging it.       A lot of the older keys were stored near basement oil furnaces and you might need to loosen up the grim with rubbing alcohol in moderation. 

The nickel plating can be cleaned with some cotton balls and your choice of metal cleaner.   The nickel plating on the old keys comes off really easy, so you have to be careful to use only the slightest pressure.    The bakelite finger pieces can be difficult to remove without damage -- if the key has corrosion.   I’ve soaked them in mineral oil for a few days while still attached to the arm by placing the arm in plastic baggy with the mineral oil.   If you have one of the newer keys, the plastic finger pieces can break if you don’t first loosen the set screw before unscrewing the knob!!! 

The coil springs for the dot and dash arm can get compressed over the years.  It’s easy to uncoil them and put new life back in the spring by using a couple of small knife blades or other instrument to pull the coil apart.    This is especially true of the dot arm coil spring.  Most dot arm coil springs have a small loop on one end and a big hook on the other in order to attach it to the keys frame.   So take great care to not damage the dot arm spring.     If it should break, you can do what Les Logan did on his line of Speed X keys.   Just add a coil spring around the left side stop screw.  Take a look at the pictures of the Les Logan keys in this journal.   

After the key is cleaned and the piece parts attached back on the key, there are a few steps necessary to bring all the parts into perfect alignment.   If everything isn’t square and lined up perfectly, you will never be able to fine tune it for proper keying.  

The Dot contact post is fixed in position but you add or remove insulating washers under them.   The alignment of the dot contacts can be fined tuned by moving the pivot point up and down in the yoke as long as the end of the dot still contacts the damper at or below center.  I've found its best for the contact with the damper to be a little below center if possible.   

1. After the dot arm contacts are square and in perfect alignment, then the moveable dash contact can be centered in perfect alignment with the dash contact post. 
2. Most everyone wants a very light touch to the key.  But the only way the dot arm stores energy to the make the dots--  is with the dot coil spring tension.   So you need to have a pretty heavy spring tension in the dot arm coil spring or you wont be able to send error free dots.   If you have been using a paddle, it will take some time to get used to the extra spring tension needed for the mechanical dots.   Getting the dot arm spring tension correct is the most critical part of the process of fine tuning.   In this case, more is better up until the point where it causes fatigue.   Thats why you see so many of the commercial CW operators screwing the key to the desk. So it wont move around and you can slap it has hard as you want to make good code :-)  The Vibroplex keys from the early part of the century came with a hole already drilled in the base for a mounting bolt :-)
3. Set the dot arm right adjust screw so that the arm just barely makes contact with the damper. Its very critcal to have the dot arm just barely touching the damper while at idle.    Set the dot arm left adj screw so that the dot arm travels about 1/8 inch or so.   The official Vibroplex adj procedure calls for using an old analog type of VOM across the dot contacts.  Adjusting the dot contact spacing so that you have 50% deflection of the VOM.    And that does provide close to the correct weight to the dots.   When I first started fine tuning keys, I did it that way.    But now I just listen to the sound of the dots by keying the rig or code practiceset.   Depending on band conditions, there are benefits to having a very light weight sounding dot. When signals are weak and background noise is loud, it can be easier to pick out light -- well defined dots.
4. The quality of the dots depends on several factors. 
1. The main spring material makes a big difference in dots.  If the dot main spring is very stiff, then the dots produced will be very high speed -- even with several weights at the far end of the dot arm.   It’s the luck of the draw.  Some keys have weak main springs and some have very stiff main spring. If you’re lucky, your key will have a moderately stiff main spring and allow slow speed dots with just two weights.  Far too many keys were produced with main springs so stiff that the slowest dots were over 30wpm with two weights.  And that’s one reason why you hear so many hams sending such high speed dots with long dashes.  If the main spring isnt strong enough, then the dot arm can tend to  flop around on the damper and causes erorrs.  So the quality of the dot arm main spring is critical for good code.

1. After you get a good dot arm coil spring tension, --- the dot arm is just resting on the damper, ---you have about 1/8 “ or less spacing in the dot contacts.  Then listen to the dots produced and adjust the contact spacing till the dotshave the proper amount of make and break time for good sounding dots.  You might have to move the left dot arm stop screw in or out till you find the correct settings.  Then use an old analog VOM to have 50% deflection or listen to the dots on a code practice oscillator.  When I was first learning how to adjust speed keys, I would work for days and days and never find the correct settings for good dots.   And it was very frustrating.   The secret is having everything in perfect alignment and balance.  With all the parts square with the other parts.  And then a pretty heavy dot arm coil spring pressure.   After adjusting speed keys for many years, I can now adjust a key by just watching the parts and listening to the clicking of the dot contacts.  And it comes up really close to the correct amount of weight to the keying.  

The biggest problem with speed keys is:  the slowest speed of the dots using two weights is usually way too high.  And when you’re first learning the speed key, you need dots down to about 18wpm or lower.   If you add 3 or 4 weights to the dot arm, it can become unwieldy and that causes errors.  The best way to slow the dots down is to use a dot arm extender---  to place a small weight further out on the arm,  like in a pendulum.   One way is too use a  sliding extender -- that places the weight to the rear of the dot arm at slow speed.  At high speed, the entire length of the dot arm is the same diameter.  And that allows for higher quality -- high speed dots.    Its very slender and light weight and allows sending perfect code.    There are pictures and a full description of the Extendadot later in this journal. 

The final test of speed key performance is too compare the quality of the dots produced at the lowest and  highest speed.  If the key dosnt have any issues and its adjusted correctly, it will produce high quality dots at all speed ranges.   Try moving the finger pieces up an down and there should be no movement at the end of the dot arm. Wobble of the pivots or other issues with the dot arm cause the dot quality to change with speed.    There are a few keys you run across with such weak main springs that there is no way the key can make proper dots.   When the main spring isnt strong enough, the dot arm will flop around on the damper, and that causes dot errors.   I've seen some keys that someone had used a grinding wheel or file in an attempt to remove part of the main spring to slow it down.  In the end that sort of mod just causes it to flop around more on the damper. 

I’ve noticed the Vibroplex keys had consistently better main springs than most other keys.   Around 1940 Vibroplex started making deluxe speed keys with Jeweled Bearings.  If the Jeweled Bearings in the deluxe Vibroplex's are adjusted correctly, it can allow the key to be used with a lighter touch and that in turn usually produces better code.   What other keys have been sold with Jeweled Bearings?   Yep, there is none other than the Vibroplex Deluxe Jeweled Bearing! 

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