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Saturday, March 6, 2010

Dover update: Falling from tree, B2 inheritance?, HB variometer

That's me (the new boy in the workshop) at the key of Ian G3ROO's B2 spy set. Beautiful rig. You will all, I'm sure, understand Nigel M0NDE's question to Ian (see below). The Dover variometer project is very interesting (picture at the bottom). Thanks Nigel! (Try to keep Ian at ground level, OK?)

Hi Bill, a Dover construction club update:
Ian was cutting down some trees in the garden this weekend, and took a tumble. As he fell I asked him if I could be left the B2, I can't tell you exactly what he said but you can imagine. Fortunately he was not injured as the ground was soft with all the rain we have had. The B2 remains in the museum for now.
The black hole has taken the variometer from us forever so a new one was made Thursday night at club. You got the blame tonight for anything that was not in its proper place when sought, the new boy in the workshop always takes the blame!
A length of plastic drain pipe was selected. A coil of about ten turns was wound around a large capacitor as a former and tied off with beeswaxed rafia then mounted onto a plastic rod. The plastic rod had a hacksaw slot put in it lengthwise to facilitate the copper wire exiting the plastic pipe. The plastic pipe was drilled and squeezed and the coil inserted into the pipe. The rod was held in place by friction fit brass washers. Two coils were wound around the plastic pipe,in similar directions. The wire is just tensioned by being passed though holes and threaded in and out of the pipe at each end. A plastic screw allows the inner coil to move through just 180 degrees. The first test showed two inductance ranges were possible 6-12 micro Henries and 12 to 21 mH. We will add additional coils up the pipe to give 21 to 30, 30 to 40 etc. A ten meter fishing rod will form the vertical element, with this variometer and switched coils providing the tuning. The experiment continues next Thursday night.
73 de Nigel Evans M0NDE QTH Dover

3 comments:

  1. Besides the B2 I regognize a wartime British R109 battery receiver and a postwar Larkspur R210 receiver in the photograph. Bill. did you make a QSO with th B2?

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  2. A very interesting design. I hope Bill will post an article with a drawing of the design.

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  3. When the variometer tuner is complete and tested, I will publish its design.

    I do not think Bill can disclose much detail of his clandestine operations. We made him sign the Official Secrets Act 1989 before entering the Spy Museum and using the callsign GB2SPY. ;>

    73 Nigel M0NDE
    White Cliffs of Dover UK

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