Straight Morse Key - How to set up....

I have been asked, several times, to write a piece about how I set up my straight keys... and so here it is...

 A straight key, is a basic, ON / OFF switching device. used to transmit Morse Code using a Landline, or a Radio Transmitter, or a flashing light.  The principle behind the code is the length of the dashes and dots, and the relationship between the two ( long and short) period of time that the key is actually in the ON position.  A Dash, or "dah" is equivalent to 3 Dots, or "Dit" or "Di "as in the famous letter V used for testing the key... "Di Di Di Dah"... The space between letters in one word is equivalent to one dot... and the space between words is equivalent to one dash..

To send morse properly, requires some skill, and understanding of that relationship,  the more you use the Morse Key, the easier and more "fluent" the operator becomes, which increases his speed of sending.  However, it must be appreciated, that it is no good sending fast morse, if the guy at the other end, cannot receive it correctly , or understand it correctly, and at a speed that he is comfortable with receiving it.....
. ... also it is no good sending fast morse, and making lots of  mistakes, .. this, in effect, slows down the actual words per minute count, due to error correction.

 Therefore, it is preferable to make good morse slowly and accurately... or , as I was told by my instructors in the Royal Navy... "Accuracy is more important than speed"...  That was true in 1960 and is still true today.

With that in mind, it should be obvious that the settings of the key should be understood, and so, I shall try to explain what to do, and what each function does, and how it will affect the morse being sent on that key.

Here is a drawing of a straight key...  not all straight keys look like this, and indeed, some have different arrangements for the spring tension, and pivot point, but the basic information about the settings will become obvious, when compared to the key you are trying to set up, according to these instructions...

To make a start.... have a look at your key... and make sure that the rocker arm is roughly parallel to the base, or horizontal,... as in the drawing.     The next thing to consider is the actual front contact points...   Here you need to use some fine wet and dry paper, in a strip, to make the contact points clean. by just holding down the key and tightening the gap adjuster ( front or rear , depending on your key ). so that one thickness of the wet and dry paper is "just" gripped... draw the paper across the points and repeat about 3 or 4  times. ... , then turn the paper over, and do the same again...
This "should" make the contact surfaces "level" when the key is closed.... ... If the rocker arm is tilted forward or backwards,.... only one edge of the Rocker Contact, will make contact with part of the base contact.... then the contact points will not close properly on a level surface, and cause key chirp, or incorrect, unwanted contact, so that is why it is important to start with the rocker arm "horizontal" as in the picture.

Once you have done the initial clean,... slacken off all adjustments.... If your key has pivot points with a screw thread on the side ( as shown in the picture),... then you need to slacken them off too..  Your key may not have side screw adjusters,.. but you still need to make sure that the rocker is free to move up and down... Use some WD40 or sewing machine oil on all friction parts, where the pivot is making contact with the upright supports. If there is wear on your rocker pivot, you will probably have problems sending, even though you adjust the rest of the key properly, so you may want to consider how you can refurbish the worn rocker pivots, or replace the key with one that has no wear, or sideways movement on the pivot point.  (Check it by holding the key steady and trying to move the knob from left to right.... )

Set the front and rear contacts (A & D )  to make the rocker arm horizontal again...  then tighten up the side adjustable pivot points until they "just" grip the rocker, making sure they have enough "grip" to prevent a sideways ( left to right ) movement of the rocker arm... Any sideways movement here, can alter the gap on the front contact by a hairs breadth, and cause incorrect keying. .. This adjustment is important.... and although it needs to hold the rocker arm steady, it must also allow "free movement" up and down on the rocker arm... If it is too tight, you will need to have more spring pressure or spring tension to return the rocker to the "off" position quickly enough for the key to work properly. Too tight, and it will also tire out your wrist action, and make keying uncomfortable or hard work,  after a short time.   Too slack, and it will move from side to side, as mentioned previously.

To check the "free movement"... slacken off the Gap adjuster ( front or rear depending on  your key)... so that it has a LARGE gap... and just test the movement of the rocker by quickly tapping the knob and watching to see how quickly it returns  ( you may need to add some spring pressure/tension, but don`t overdo it... "Just Enough" is the motto ... )

 a word about the springs on straight key...

Front springs, are usually PRESSURE springs.. where you have to screw down  to adjust how much pressure is needed in the spring below, to force the key "off" and back to rest position.

Rear springs are usually TENSION springs, where you screw an adjuster "out" or "up" to increase the PULL down on the rear half of the rocker arm, to pull the key "off" to the rest positon.

The amount of Tension or Pressure, that you have set on your key, will decide on how quickly the key returns to the "off" position, and also will decide the speed at which you can send... If you have a "strong" spring pressure or tension, it will bring the key off quicker, BUT, it will also slow down your sending, because you need more pressure in your wrist action to make the key "on"... and that will make your wrist tired quicker, and make more mistakes... and so, it is a "fine" line to adjust the spring properly for your sending style.

The next thing to do is to set the gap.... Tear off a strip of paper from a normal A4 paper as used for printing out letters, etc...about 20 mm wide will suffice... and place it in the front contact gap, and then adjust the gap with the rear gap adjuster ( or front, if no rear one on your key ).. until it "just" nips the paper.... remove the paper and check the "free movement" by tapping the key...  now is the time for you to adjust the spring tension, or spring pressure, depending on which type B or type E you have on your key... ... Practice sending some words ( not connected to your transmitter).. to see how the key "feels"...  and adjust the spring tension/pressure according to your way of sending.

And that`s about it..  ... from this "initial setup" you should be able to make "fine adjustments" of the gap and tension/pressure, to suit your style of sending...

Once you have adjusted the spring tension/pressure, and set the gap, even small adjustments on the size of the gap, can alter the timing of your sending symbols, and subsequently, the speed that you can send at...

 As a really bad example of this.... If you set your gap at ( say ) 5 mm  and you sent some symbols, it would be ( say ) 10 wpm maximum because of the actual distance the rocker ( and contact closing time ) arm has to travel.... now if you reduced the gap to ( say ) 2.5mm... and sent the same symbols it would ( probably) increase the maximum speed to ( say ) 15 wpm.... and so on... the smaller the gap, the less time the rocker takes to close and open during your sending of symbols, and consequently, the smaller the gap, the quicker you are able to send...

 This does not mean, that by setting the gap very fine, you WILL send faster, because, of course, it depends on your skill and training levels. You can still send slowly with a small gap though ! ! !...

Remember... Accuracy is more important than speed..... and try not to send faster than the other guy can receive accurately.... !

I hope it has helped you to set, and get the best, of your straight key

The video below, shows me using an Admiralty Pattern 7681 Straight key, adjusted according to the instructions above.... as you can see, I do not use the key in a conventional "Hold"  I just tap on the spark guard.... I got my knuckles rapped with a ruler, quite a lot, when I was in training,... but eventually, the instructors decided I could send better "my" way... than the "official" way ! ! !

 You can view the video on FULL SCREEN by clicking the square in the bottom corner.... Put your phones on,.... or turn up the volume...

I do not have a ham licence, but you can find me on CWCOM, using my keys ( as featured elsewhere in this blog) contacting people around the world, using the ancient, morse code, over the modern internet...   ( CWCOM is free to use and download from www.mrx.au )

Hope to see you there, my call is GEMS       73  VA dit dit

NATO MORSE KEY

This blog is about how I refurbished the points and adjusted the spring tension on my Chrome Covered NATO morse key.

This key, based on the swedish design key, ( Lennart Petersson )  ( also known as "the swedish pump key")  uses a spring plate for the support and spring tension on the main rocker/sending arm. There is a spring tension adjuster, using a spanner and an allen key, that can only be accessed by removing the cover.  

. The switch on the front of the key, is for switching the key "out of circuit" of any transmitter, thus giving the operator control, and can prevent accidental keying by knocking the key.

The key was made by  Marconi S & R systems Ltd, from the late 60`s onwards, and also by Pryce Edwards Ltd. The key is a heavy one !... it weighs in at about 3.5lbs ( or 1.6 kg ).so it "sits" well on the desk. and doesn`t move when in use ! ! ..

I understand that the key had several different types of cover made for it... consisting of mild steel, brass, and fibreglass.   As far as I know, I have the only Chromed Cover key.... I am assuming that some previous owner had it done. .The normal colour of the key would be "navy" eggshell pale blue, or pale green. as can be seen in many pics available on Google Images.

So, I removed the two small knurled nuts on the casing to reveal the key inside.....

 on my key, there is a missing part, which is a connection block, that sits behind the key at the back end.


The gap adjuster is the round black knob on the top. (If you remove the knob, be careful not to lose the "pin" that controls the gap adjuster)...

It is annotated with numbers from 0 to 9, and originally, 0 would have caused the key to be "on" all the time, so that would be the minimum gap... The rotation of the knob, increases/decreases the gap,... the position of the knob is held in place by a simple sprung "peg" underneath the cover, and locates in a slotted ring under the knob..

.(If you remove the knob, be careful not to lose the "pin" that controls the gap adjuster)...

To remove the rocker arm, only requires the slackening off, of the two screws on the main support,

and sliding the rocker arm back towards yourself.

 the spring plate has two cut outs for securing it when the screws are re-tightend.

Once removed, I noticed that the actual contact point, was worn, somewhat, so I decided I would have a go at rebuilding it using ordinary solder.... to do this, I employed the gas cooker method !. (because I don`t have a gas blow torch! ! !).....

. I set the rocker arm in my portable vice, for two reasons... firstly, to act as a heat sink, against the plastic "business end"... and secondly, just to hold the arm firmly in the gas jet to heat it up... I also used my trusty soldering iron, again, heated in the gas jet, to assist the flow of solder onto the end of the rocker..

. When I had decided there was enough solder, I removed it and cooled it under the cold tap.!.. then I carefully fixed it into the vice so that I could file the surface of the solder to level it out. and present a good level surface for the adjuster knob to make contact with..

 Some will say that the solder is too soft for the job,... but it won`t make "that" much difference, because when it wears down again, it will be a simple job to rebuild it again.



Putting it back together, was simple enough,... just making sure that the "tongues" of the spring plate were pushed home firmly, before tightening down.... then it was a matter of replacing the gap adjuster, and re-setting the spring tensioner with the allen key, before finally putting on the Chrome Cover, and doing a test piece...