Head-phone Connections

Radio Record, Volume III, Issue 18, 15 November 1929, Page 26

Head-phone Connections

B= careful to see that the tag of the telephone marked "positive" is eonnected to the correct terminal on your set. Many sets are marked with "nositive" and "negative" on the telephone terminals, but if your set is not so treated look inside and see which of the two telephone terminals is connected directly to the high tension positive. That so connected is the positive telephone terminal, and your positive telephone tag should always be connected to this particular terminal. This is not a fad, but is due to the fact that if your telephones are pro-

perly conneced the steady plate current continually passing through them will add to the permanent magnetisin of the telephones themselves, whereas if they are wrongly connected this current may steadily tend to demagnetise your ’phones, reducing their sensitivity considerably. — Telephones which have been dropped frequently often are far less sensitive than those which are properly kept. The reason for this is that any jolt or jar tends to upset their magnetism. It is not, of course, suggested that a sereened-grid valve is essential in every kind of receiver, but for the modern, up-to-date multi-valve set, capable of bringing in twenty or thirty stations, the screened-grid valve naturally is incorporated. — ms we