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|Peter's finished key|
Of Paddles and Things
A few weeks ago I was at my other club, Farnborough and District Radio Society, when a fellow member brought in his new toy to show us. It was a beautifully crafted CT755B Single Lever Paddle in highly polished solid brass monogrammed with his Call-sign. Made by Yuri, UR5CDX, it weighs in at about 1.5 kilograms (so it’s not going to walk across the bench if you are a slapper like me)! It has a lovely action using Rare Earth magnets rather than springs, but at about 130 Euros, plus shipping, for me it would it would have been be a real extravagance to buy one.
On reflection, after playing with the key for only a few minutes, I felt sure that, being a fairly simple design, I could build one similar to this myself. And that’s what I decided to do. The pictures show the results: one of the finished article and the other of me using the key in the shack.
I had no dimensions to go by apart from the dimensions of the base as described in the UR5CDX sales literature, but with some pictures of the key, downloaded from their website, I was able to scale it roughly. I’m chuffed to report that WVARG club members who have played with the key have been very complimentary in their remarks.
At the outset of the project the base was the main concern. It’s always a problem finding a block of metal large enough to work on, but scrabbling through my scrap box I found a lump of brass about 80mm square and 25mm thick: perfect, once I had machined all the surfaces! Rather than having to drill all my fixing holes, etc., right through the base I opted to mill a cavity in it deep enough to clear the screw heads. I then mounted the mechanism on a brass plate which in turn I screwed to the base, giving a much cleaner look overall.
|Peter, M3OSP operating with his key|
Adjustment is much the same as for any conventional single or dual lever paddle. At the rear there are two adjusters to change the contact gap and at the front are two pole pieces with which you can adjust the “spring tension‿ so to speak, by moving them closer to or further away from a central magnet.
It’s difficult to say how long it took to construct the key as I don't have to clock on and off anymore (!) but I guess it was a little over a week doing a few hours here and there. I tend to spend a lot of time thinking about any job beforehand, going through my scrap boxes to see what I can use without too much machining work. On previous projects, where I have had to purchase materials, I usually got a bit extra for future use. For this key I was able to find all the materials I needed without buying anything extra, so in that sense, it cost me nothing other than my time!
I have a relatively cheap Chinese made lathe and small milling/drilling machine, not the best, but, after some fettling, they are both adequate for my needs and limited skills. I would say there is nothing I have done in making this key that could not be done with just a basic drilling machine, a hacksaw and some files..........plus a lot of patience!!
The hardest part of the job, in terms of labour, was the base, initially cutting it down to approximate size with a hacksaw then facing off the sides on the lathe. Milling the cavity under the top plate was not difficult but just took time because I could only afford to take small cuts so as not to overload the mill.
I don't suppose I will use this key very much myself (preferring a straight key or bug), but it makes a nice addition to my collection.
You can see the complete range of UR5CDX's keys (and they are rather tasty), on his website at www.yr5cdx.com (click here), or on Vine Antenna's website at www.vinecom.co.uk (click here), who appear to be his agent in this country.