Tips and Jottings

Radio Record, Volume IV, Issue 17, 7 November 1930, Page 8

Tips and Jottings

A SLIGHT smear of oil, followed by a polish with soft, clean duster, will often restore an ebonite panel that has gone "off-colour." Tf the aerial is allowed to touch or swing near a gutter pipe, tin roof, or similar large’ metal surface, you may be troubled by "fading." [* you are troubled by loud speaker _rattle do not forget that this is sometimes due to a small nut becoming loose, ‘ V HEN two aerials run close together there will be interaction between them, and this will affect the sel¢tivity of both sets. ! JEEP your aerial as far away froma your neighbour’s as possible, as running them close together will give rise to many undesirable effects. ONE of the lesser known advantages of the output filter circuit for the loud speaker is the fact that it frequently improves stability, more so in shortwave. "PR" BATTERIES which are partly run, down will often give rise to buzzing and cracking noises which are particularly noticeable if good audio transformers are used in the set. ORE old-fashioned cure for electrical interference picked up from adjacent electrical machinery is to try a new earth. A fixed condenser placed in series with this can often eliminate,~ or greatly reduce hum. [® your detector seems to work just as well without a grid leak as with one, it is possible that there is a leak across the valve holder or on the base of the valve. (GENERALLY speaking, it is inadvisable to modify the circuit of a portable set except to a very small extent, owing to the fact that there is no space to spare in such a set. MANY experimenters have found that better results may be secured in the operation of screen grid receivers if the lead between the coil and the cap of the valve is shielded, and in some eases earthed. An inexpensive makeshift for this purpose may be arranged by taking a piece of insulated wire, such as rubber-covered stranded wire, cutting pieces of tinfoil jin. widegand 4 or din. long, and then winding thyse strips of tinfoil smoothly around ‘the rubber covering on the wire. After this . operation, a flexible wire may be bound round the end of the tinfoil and then taken to earth, if desired.