AN EFFICIENT WAVETRAP

Radio Record, Volume I, Issue 31, 17 February 1928, Page 13

AN EFFICIENT WAVETRAP

A CONVINCING TEST, A reader residing at Roseneath, less than half a mile from 2YA’s _transmitter, writes the following: "I must Say a word about the efficiency of the wave-trap circuit published in your column. Although I live in Roseneath and have an unselective BrowningDrake set, I can easily cnt out 2YA and bring in 8YA and 1YA. I have not tried 2B, as yet, but will do so when conditions are more suitable. I find it best tapped at the 18th turn in preference to the 10th." This circuit was published on Jann-. -aty 13th, and is an adaptation of the selective crystal set circnit, which makes a good trap when constructed complete. Readers have already been advised to find the tapping best suited to their situation, and in seme cases the inclusion of the whole coil may be found better than a tapping. The crs stal set was described on January th.

A quality miusic-reproducing audio transformer now obtainable in New Zealand is the Igranic-Pacent Super Audioformer, having the high primary impedance of 124 henries and a ratio of 8 to 1. The published curve shows a flat or even amplification from 4000 down to 300 frequencies, which is quite unusual, and, moreover, was made clearly evident by a practical test. In the second stage large volume was handled with wonderful clarity down to the lowest frequencies usually transmitted, and in the first stage results were also highly satisfactorv. The International Radio Co. Ltd., Courtenay Place, Wellington, has just landed a supply of these latest transformers. During the past few weeks quite a number of coustructors of the Brown-ing-Drake receiver have written reporting splendid reception of New Zealand stations, but stating that all Australian stations have heen very weak. The reason is chiefly attributable to the fact that whilst daylight saving is in force in New Zealand, the Australian stations cannot be received at good strength until a late hour, Having in mind the usual amount of interference in these stations, the writer seldom Eroubles to tune them in at the present ime. (END OF CONSTRUCTION SECTION)