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Friday 29 August 2014

Hi Mound HK-708 Refurbishment

I use CWCOM, a program that enables us to communicate using CW , or Morse, either from the keyboard, or from a "proper" morse key connected to a laptop or PC.  An excellent program that can be made to work with Linux OS as well as Windows OS. It enables those of like mindedness, to practice and preserve a very old, and original DIGITAL, method of communication, world wide, without the use of high powered transmitters and receivers... No antenna, ( aerial ) in the garden... and no Amateur Radio Licence is needed... All standards of user are welcome... Over a period of 18 months, I have made over 220 contacts, world wide.. some only briefly, but others have become "regular" and interesting contacts..I have already posted a video of me operating my Hi Mound HK-705 from my car, as a "mobile" operator... and recently a friend in Japan made contact with me, whilst he was travelling on the Bullet Train, doing 186MPH.... I have also made contact with a guy in the Bay of Biscay, on his Catamaran, whilst he travels to the mediterranean for his summer vacation.

One of my original contacts, Mike, who lives in Harrogate, Yorkshire,...  sent me his old Hi Mound HK-708 straight key, because he has arthiritis and cannot use it any more, he uses a paddle key.. On arrival, the key certainly needed some cleaning... so I just took it to bits, and gave it a good scrub with an old toothbrush, and some soapy water,...I repacked the bearing caps,  using Flora Margarine, and put it all back together....

 Looking very smart, then I started to get the setting of the tension spring and the gap, so that it was easy to use.... Unfortuately, the big knob on it, became very slippery, due to the way that I send morse....(  tapping on the knob, instead of actually holding it in the "correct manner". !..}   . I normally use the spark gap skirt, to transmit on, but the HK-708 did not have one... Doing some research, I found a supplier of plastic discs,

www.AcrylicCraft.co.uk

and I ordered 5 discs with a 3 mm centre hole...



after arrival, two days later, ( excellent service ).. I decided that I needed to "round off" the outer edge, so I put a 3mm brass bolt and nut in the centre hole, and ran up my battery powered drill, with it in the chuck, using a file, and some fine wet and dry paper, I had the required round edge all finished within about 5 minutes... You can see the rounded edge on the one fitted to the HK-708 in this pic...



When I came to fit the skirt, it was about the same size as the knob, and so it was difficult to use... I decided to swap the knob with another key, which knob was made from a wooden drawer knob from the local DIY shop !.. Because of the bend in the rocker arm of the HK-708. I needed to secure the skirt and knob, on top of a securing nut just under the skirt... which you can just see on the video... Resetting the tension spring and the gap, did not take very long, and you can now view the video of me sending a test transmission using the key..   It works very well, and will probably become my favourite to use key for a while....

Here is the video... I hope you can read morse ! ! ...( speed is about 22 words per minute )....