Page:Handbook for Boys.djvu/232

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Tracks, Trailing and Signaling

well insulated from the ground, and all connections in wire, perfectly solid. It is advisable to solder every connection and to make your aerial strong as it has a great deal to do with the working qualities of the station.

After this is completed, the inside work on instruments should begin.

  1. A pair of watch-case receivers having a resistance of 1000 ohms each, manufactured by a reliable firm.
  2. A loose coupler tuning coil of about 8oo meters.
  3. One of Mordock's metal detectors or one of similar design
  4. A variable condenser of about 5–10 plates.
  5. A fixed condenser so arranged that its capacity can be changed if desired.

With these instruments the receiving set is complete, so we next take up the sending apparatus.

  1. A two-inch induction coil.
  2. A heavy spark gap (zinc preferable).
  3. One wireless key with heavy contacts.
  4. A plate condenser which can be easily made by any sc6ut. Good glass is the main point.
  5. A triple pole, double throw aerial switch. (Can be made by scouts.)

Now you have everything necessary to go ahead and assemble your station. The next thing is to connect them up.

Above is a diagram which will make a good station for a scout. This station, if the aero is of the proper height, is capable of sending messages from 8 to 10 miles.

The Receiving Set

Perhaps the most fundamentally important part of a wireless telegraph station is the aerial. Its construction varies with each station, but a few general suggestions may be of use.

The builder should aim to get as high and as long an aerial as possible, height being the more important factor. In a stationary set the aerial may be fastened to a tree or pole or high building while in a field set a tree or an easily portable pole must be used.

The aerial itself should be made of copper wire and should be hung between spreaders as long as convenient and insulated from them by two cleat insulators in series at each end.

The experimenter should see that his leading-in wire is placed conveniently and comes in contact with the walls, etc.,