NEUTRODYNES CAN HOWL

Radio Record, Volume I, Issue 5, 19 August 1927, Page 13

NEUTRODYNES CAN HOWL

IMPROPER NEUTRALISATION. | Many New Zealanders are under the misconception that neutrodyne receiving sets cannot bowl and interfere with reception by other listeners. A neutralised receiver, nniess it is carefully adjusted, can be less efficient than one in which neutralisation is not employed. There are three chief ills of improper neutralisation, according to an article in the July American Radio Broadcast magazine. "The first and most obvious manifestation of incorrect adjustment of the neutralising device is oscillation in some or all of the radio-frequency circuits,’ reads this article. ‘’lhese oscillations as a general rule become more severe as the frequency is increased, and & loud squeal or whistle will be heard as the tuning controls are adjusied to receive some station that is transnitting. Recelver Will Radiate. ; "Such an effect will make it diflicult for the user of the receiver to obtain satisfactory reception and the oscillations will be radiated from the aeria) attached to the receiver and cause interference on other receivers located in the neighbourhood. Snech oscillations can be prevented by correct adjustment, and it is essential that the proper setting be determined in order to make it possible to obtain best results from the receiver, "A second detrimental effect of mal‘divstment of the neutralisers is poor quality, which is generally due to the existence of too much regeneration. The gualitvy, under these conditions, will generally sound dsummy, indicating that the various frequencies in the carrier are being unequally amplified by the radio-frequency amplifiers. ‘lo preserve good quality, the radio-fre-quency amplifiers must amplify without distortion 2a hand of frequencies extending about 5000 cycles above and 5009 | cycles below the carrier frequency, and this condition does not exist unless proner neutralisation is obtained. Prevent DX Reception. "Another effect of improper nentralisation is to cause one or more of the tuned circuits in a single-control teceiver to be thrown out of synchronism, so that the set loses a great deal of its seusitiveity, and as a result it is not possible to tune -in distant stations with satisfactory yolume. ‘These three major effects of improper neutralisation indicate how essential it is that neutralisation be always carefully and completely accomplished."