Notes by the Way

Radio Record, Volume II, Issue 4, 10 August 1928, Page 5

Notes by the Way

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FINE "frequency test’ by 2YA Wel- ’. lington created’ all round interest. ‘Many loudspeakers jibbed badly at the audibility tests when the overtones reached the shrill whistle stage. in brief, this simply means that some receiving equipments (not necessarily the speaker alone) cannot reproduce the notes from certain instruments with all their overtones, and thus absolute trueness of tone is not obtained. OWEVER, a sufficient number of overtones arergenerally reproduced sufficiently audibly to be fairly close to the real thing, and only a "superenr"’ could detect the deficiencies. The "YA Wellington frequency tests pro-. vided an attractive feature of the proeramme. It was noticeable that the pitch of some of the notes changed distinctly during the first two or three seconds they were being sounded. "y HAT is the average efficiency life of » good valve?" is a question of a prospective beginner. The average life can be put down at 1000 hours, but some innkes exceed this. To prolong the useful life a valve its filament should not be burned too brightly. The rheostat should be adjusted to give just the best results and not turned any further on. Pun eolloid rectifier used by numerous listeners for charging their wet B batteries is apt to get over-heated after a few hours’ use. Several listeners have inquired how to meet this dif- . ficulty. My own practice is to stand ihe colloid in a large bowl of cold water with the water a fraction of an ine¢h above the brown liquid in the colloid. The colloid can stand in the bowl of water while it is operating. The water in the bowl can be easily changed when it warms up. This keeps the colloid cool. AN up-country visitor wishes to know A. : eas . . what is the ef a step of radio frequency. The prac: . jice is to calculate the increase in ‘signal strength for distant reception at the rate of from 3 to 5 times, or even more, dependent, of course, upon the efficiency of the radio frequency valve, correct A and B voltage, and radio fregqueney circuit, and the method of reducing the natural tendency to seltoscillation of the valve. £ WILL-KNOWN DX listener in the Manawatu asks what should be ihe value of the leaks and condensers used in a resistance-Capacity of audiofrequency amplifiers. The coudensers should be about .01 mfd. and the resistances about 1 megohm. "N 11." (IHataitai) states that his "neighbour claims to be able to hear howling valves per medium of his crystal set, and he questions this, It. is quite possible, providing the howling valve is fairly close to the crystal set, but both sets must be tuned to the same broadcast station. Kvidently some genius starts his vaive howling on ®YA Wellington. which is the only station likely to be tuned in by the _ "gystal set. of im Sh) e . have asked how i oe ee bona mth? : ont " an a receiving set. The practice is to use _ the metal parts of the airplant as an earth. and one aerinl wire trailing beneath the airplane supplies the antenna.