Tips and Jottings

Radio Record, Volume III, Issue 20, 29 November 1929, Page 26

Tips and Jottings

Mounting Variable Condensers. HEN a variable condenser with one-hole fixing is mounted on A" panel, the top end plate is usual ‘pressed flat against the back of the panel, The condenser is then held rigidly in position, the friction between the end plate and the panel assisting the fixing nut. It sometimes happens that the ends of the rods on which the vanes are mounted project slightly beyond the top end plate. When this is the case, care must be taken in tightening up the fixing nut, or the centre of this plate will be pulled in towards the panel, distorting the whole component and probably causing the, fixed and moving vanes to make contact. If it is preferred to have the end plate flat dgainst the panel, the ends of the rods should be filed down flush with the plate, or alternatively, shallow depressions may be made in the back of the panel where the ends of the rods are to rest. A Home-made Blowpipe. a QMALL repairs to the soldered connections in a receiyer may often be earried out more quickly with a blowpipe than with a soldering iron. The iron takes a few minutes to heat up, while the blowpipe is ready at any moment. A piece of petrol ‘piping a few inches long, drawn or hammered down at the end, so that there is only a small hole, is suitable for the pipe. A length of rubber tubing on the other end of the pipe leads to the mouthpiece, which may consist of an old cigarette holder or pipe mouthpiece. A candle may be used for. the opération of the blow-pipe, though a methylated spirit flame is preferable, as it is less sooty. The flame is held an inch or less from the work, the blow-pipe inserted in the flame, and the jet of flame is directed on the work. Long and steady "blasts" are better than sharp puffs of breath. A chin of solder and a little flux are put on the joint. and the heating is continue: until the solder has run into the joint. ‘