ANSWERS TO CORRESPONDENTS

Radio Record, Volume I, Issue 22, 16 December 1927, Page 15

ANSWERS TO CORRESPONDENTS

(By

Megohm

BROWNING: DRAKE, R.T. (Hawke’s Bay) has an American faetory-built B.D., 5 valves, resistancecoupled. audio. Reception is very weak and lacks quality. Replace the P.M. 6 with a P.M. 256. One or -nore of the resistances may be faulty, so procure a: new one of the same kind and try it in place of each one in turn. If still unsatisfactory, write again. ! G.H.B, (Christchurch): If your fac-. tory-made B.D. blasts on heavy it could be improved by placing a) valve of lower impedance than the pre-. sent 6000 ohms in the last audio. As_ -you contemplate adding a Ferranti, transformer, you will ouly require one, an A..F. 3, and this must be put in ‘place of the second one. The output filter can be procured as a complete ‘unit for connecton outside the s¢t, and will reduce overloading of the speaker and thus allow of more volume. Your Aerial is quite suitable, but your set is

rather wnselective, even though only | three miles from 3YA, Advice given, through this column is free, but limited to a:Feasonable amount. j.N. (N. ‘Wairoa): The pyrex insulators alone should. be -quite efficient, and would not cause the rushing sound, wiich you experience every evening. from 7.45. The trouble is probably caused by general radiation from neighibouring receivers. CRYSTAL QUERIES. Polar {Manawatu) is 90 miles from 2YA,. gets good results on two-valve set, but fails to get 2YA on ‘‘Record"’ crystal set with carhorundum. Look the | set over carefully-see that ali joints are good-it is easy to leave a fine streak of enamel on the end of wire]

that when clamped under a nut will give complete insulation. W.R. (Eastbonrme): A two-valve amplifier for erystat appears in this page in ‘‘Record": for December 2, and a one-valve amplifier appears on Aungust 26, C.M, (Clevedon): I do not know that the new crystal is yet stocked in New Zealand. If the galena crystal is played -ont, scrape the top surface away liberally, and you will probably get better results, Some of that type of crystal. are not as good as they should be, From your description it is difiicult to tell what is wrong with your ‘phones. Perhaps the diaphragms are too close to the magnets, which would necessitate either turning the diaphragms or adding a ring of thin paper to increase the distance.