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Sunday, 15 February 2015

Admiralty Pattern 7681 - Re-Build ! !

My original Admiralty Pattern 7681 morse key, as seen in this pic,



Has been radically changed several times, for experimental purposes !.. however, I recently discovered a source of very nice quality "Mahogany type" bases....


 and thought that it might be a good idea to re-build that key, onto a new base...  ( the Birds Eye Maple base, looked nice, but had some damage to it, and also it was rather large and cumbersome, rendering the key to an unused status symbol ! )...I also wanted to  return the rocker arm to it`s original size again... The original rocker arm was well and truly worn out, and no good for a rebuild, so obtained some square brass bar from a supplier on Ebay... When it arrived it had a bad scratch mark on it, from where it had slipped in the vice when it was cut !.. ( as you can see on this pic...)...



 never mind.. I may be able to fix that... we`ll see...

   After it was cut to size, I then marked up the balance points, using a sticky label, and securing the rocker arm between the pointed adjustable pivot points.  Once I was satisfied that they were in the correct place, I used my small drill bit, to "dent" the brass, and give the points some place to lodge.... the next thing to do was to measure up and mark the drill points... one for the rear gap adjuster, the next for the spring tensioner, then on the other end, the contact point, and the knob.

The rear adjuster needed to be threaded,  so I had to purchase a set of reamers on ebay... very quick supply, ( next day ).. so no hanging about... I drilled the holes, with a pilot hole first, and then to size, and reamed the adjuster thread into it... the underside of the spring adjuster needed to be "countersunk" to allow the maximum "pull" on the thread, bringing the top of the spring into the rocker arm... at the other end, it was a case of finding a small brass machine screw, with sufficient length, to act as the front contact point... again, I used the reamer to put in a thread, so it would be "tight" when finally fitted and screwed right down... the knob is threaded internally, so all I needed was a clearance hole for the machine screw to fix the knob...





A refinement, I thought, taken from a bakelite AP7681 is a flat sprung metal connector to ensure the rocker arm is electrical connected to the main frame,... this required a very small screw in the underside of the rocker arm...  ( you can see the sprung metal connector in this pic )...




Once all the bits and pieces had bee worked on, and fixed to the rocker arm,... it was time to consider the positioning of the main frame, onto the base.... to help to keep the base free from scratches, and to give me somewhere to "mark up".. I cut a piece of plain paper to size, and stuck it down with some blu tack on each corner...







I then found the centre line... and placed the rocker and main frame onto it... Once I was satisfied that it was in the correct place... I used a pencil to mark the holes that I needed to drill for the fixing screws, to come from underneath...



Where I could, I used a small "phillips" screw driver in the hole and tapped it with a hammer, to indent the paper, and also the wood beneath.








I then drilled pilot holes, to check that they were in the correct locations, and then drilled them according to the size of the screws that would be needed....





 Some of the screws needed to be "countersunk"  underneath, so that they would have enough thread above to fix the main frame.... also needed to be countersunk to keep the under surface level, for the final fitting of the non-slip mat.



The front and rear contact points were then located, marked, and drilled in the same way... To make sure the front contact point was directly underneath the rocker arm contact point.. I used a rule, on edge, and used the edge as a "vertical", to mark the paper where the centre of the contact point, ( and drill hole ) should be








..a channel was cut in the bottom of the base for a connecting wire from the front contact to the separate terminal.



The rear terminal does not have any wired connection,... but still needed to be secured by a screw from below.

Having got all the bits and pieces in their correct places... it was time to take them off again, to remove the paper, and dismantle completely, the rocker arm... this had to be done, to enable me to try to remove the scratch mark, first mentioned. I did this by running the naked rocker arm back and forth over some very fine wet and dry paper,  (keeping it dry).. until the mark had disappeared... doing this has also put a nice shiny surface onto the rocker arm, so I did all four sides ....




 time now to finally put all the bits back together again...

The (almost) finished key........

 a quick check with a multimeter to make certain the connecting wire was, indeed, connecting the front rocker to the terminal,  proved ok... Also did a quick test with a "flying lead" to another morse key, to check that it was indeed working... before I added the final touches, the non-slip mat, ( thin washing up sponge sheet !)







 and, of course, a new connecting lead and jack plug.


The finished key......















Below is a short movie showing the key in action..(you can make it full screen by clicking on the little square)



Just a final note.... I do not have a workshop, nor do I have any engineering background/skills, just my desktop in the lounge, with a 12volt battery drill, and a clamp on vice, to work with...

Thursday, 12 February 2015

Connection Box for Morse keys or Audio equipment

Having 8 morse keys connected to my laptop, via the USB/Serial Connector cable, via twin stereo adapter plugs, was a messy solution,...

Messy Junction !


 I wanted to tidy my desktop, and decided to make a connection box to plug all the keys into... The box I chose was rather larger than necessary, but will suffice to show the construction process, and details of the work as it progressed....

Two designs of box presentation
Depending on the space and location of the connection box, in its "in use" position, depends on the "face" where the socket holes will be drilled....


I decided that the side view would be convenient, and would sit nicely in a small space beside my radio on my desktop... so I found the centre line, then spaced the holes accordingly... 

Inside the box, there are ridges, to support small pcb`s which makes the thickness of the box a little too much for the outer fixing to grip the socket sufficiently, so I had to "pare away" or thin an area behind each hole.......



The next job was to carefully twist the lugs on the sockets by 90 degrees. 


The reason for this, is , to facilitate threading a bared copper wire through each socket, after soldering to the first one.


Once the first one is soldered, it is easy to thread on the others, before fitting them into the holes in the box,....


As each one is fitted, into the box, they slide along the wires, into positon fairly easily... soldering first, or trying to wire up after fitting, would have been very tiresome,


After soldering, tighten up the lock nuts, and trim off the excess wire,

solder on the external lead, after tying a knot in, to prevent pulling it away, when in use...

 The finished box only needs the lid screwing on.....

Make sure the connections on the "fly lead" jack, are compatible with the socket on the equipment you intend to use this box on, and follow through to "mimic" those connection on the sockets on this box.... A multimeter, with croc clip, and a spare jack would be useful for detemining the correct connections throughout.

Disclaimer.....

You are responsible for any damage to your equipment, if you decide to follow this blog instruction.. I accept no responsibility for damage to your equipment.