Radio Broadcast (May 1928-Apr 1929)

RADIO BROADCAST ADVERTISER 233 75TH MERIDIAN 07 P. M. 01 A. M. 07 A. M. 09 A. M. 1 P. M. 5 P. M. 7 P. M. Letters from Readers (Continued from page 231) From this letter it appears that the Greenwich Mean Time used in the list reprinted from the Wireless World is the continental equivalent of the United States Greenwich Civil Time. This Fact explains the following letter from a Toronto, Canada, reader of the magazine; To the Editor: May I take the liberty of pointing out an jrror in the May Radio Broadcast? At the top sf the list on page 44 of the May number you state that "all the times are given in Greenwich Mean Time (G. M. T.) " — nevertheless the times actually were given in G. C. T. (Greenwich Civil Time). Also note that five o'clock p. m. London time, which is noon E. S. T., certainly is not 5:00 p. m. G. M. T. For your information I would state the following: 1. The term "Greenwich Time" is ambiguous ind doesn't mean anything as far as we are :oncerned. 2. G. C. T. (which is the same as London time) is five hours ahead of E. S. T. 3. G. M. T. or Greenwich Mean Time is the nean day, astronomical or solar day, commencing at noon of the civil day of the same date. This was shown at the bottom of page 53, only there was another error here — all the times under '75th Meridian" were "p. m." The corrected column should read as follows: Ipage 53) G. C. T. G. M. T. 00 12 06 18 12 00 14 02 18 06 22 10 24 12 It is apparent that you listed the right times Dut called them by the wrong name and also that the two tables (pp. 44 and 52) do not conlict. It is amazing how universal this error of xmfusing G. C. T. and G. M. T. has been. \pparently people thought G. M. T. meant 'Greenwich Meridian Time." I am a ship operator and I certainly know that 10 p. m. E. S. T. is 0300 G. C. T. 1 also know that 35SW transmits phone from 1930 G. C. T., or 2:30 p. m. E. S. T., onwards. If the U. S. Naval Observatory is correct, the second column of this conversion table refers to the old Greenwich Mean Time, which is no longer used. It does not yet seem clear to us, however, whether or not there is any recognized method of time computation |em ployed at present here or abroad which begins its day at noon. An Old-T inter Recalls To the Editor: The picture of the Wireless Room on the 55 Bermuda in your June issue [page 71] came to me like a voice from the past. The gear was that of the Marconi Co. of London, a firm I worked for from 191 5 to 1927. On looking over the gear I noticed a slight error: the 5-kw. quenched spark transmitter should read j-kw. quenched spark transmitter. It is a 1925 model originally intended for lifeboats but radiates up to 7 amps, and may be tuned to 300, 450, 600, and 800 meters. It is identical with the auxiliary transmitter on my own ship. Our main installation is an R. C. A. c. w. and i. c. w. transmitter with a range of waves from 600 to 2500 meters. William I. Boobyer Radio Operator, 5.5. Beaconstreet A Correction in the July Number In the article "How to Build a Beat-frequency Oscillator", by G. F. Lampkin, in the July number of Radio Broadcast, an error occurred in the picture at the bottom of page 1 57. The two coils marked 40T should be marked 55T, and the two marked 55T marked 40T. The coil diagram in Fig. 1 is correct in these dimensions. A New and Better SHORT WAVE RECEIVER! The Aero International Four This new Aero Receiver embodies many noteworthy improvements. Uses latest design Aero Interchangeable Coils that provide materially increased efficiency of operation. Sensitivity has been increased, control made easier, noises eliminated. Particularly adapted to musical broadcasts. Uses New Kit The coils illustrated are the new L. W. T. 10 kit, price $10.50. Designed for use with special foundation unit which includes mounting base. These coils are only (Rear Panel View) 2" in diameter, insuring smaller external field and better performance. They embody the patented Aero construction feature which provides 95% air di-electric — by far the most efficient inductances as yet perfected. Write for Literature Investigate this superlative set at once. Write for complete descriptive circular TODAY. You'll find it mighty interesting! Address AERO PRODUCTS, Inc. Dept. 109 1772 Wilson Ave. Chicago, III. NOTICE Your dealer can supply you with complete parts for the Aero International Four in knock-down form. By purchasing all parts, including cabinet, in factory sealed package, you are assured of perfect co-ordination between all units. If your dealer can't supply you, order direct from the factory. Write for prices, parts list, etc. NOW. W LINCOLN ANNOUNCES e ■ a_ 1 \ s .% nsouu ■ r» -P <rr u • ■ mt H -j Curve "A" is Lincoln 105 first stage transformer. Curve "B" ia Lincoln 106 second stage transformer. Curve "C" is a $10.00 high-grade audio transformer of standard make. All curves are under actual amplifier operating conditions. Note absolute Lincoln superiority. REVOLUTIONARY A. F. TRANSFORMERS! LINCOLN offers new radio transformers of phej nomenally high amplification and precision manufacture, designed by Kendall Clough. Look at the actual operating curves for these new Lincoln products! Where have you ever seen such high amplification and excellent frequency characteristics as these new transformers offer! The new 105 first stage audio transformer haa an average effective ratio of 4.4:1 — nearly 50% more than other more expensive transformers. The 106 second stage audio transformer is 3.7:1 or nearly 25% more than other types. And the tone — it simply must be heard to be appreciated, so far superior is it to that of ordinary #8.00 and £1 2.00 transformers. No matter what set you have, or what you're going to build, Lincoln's are the best audios, for they'll give you finer tone and 50% more amplification on weak signals. POWER UNITS — B and ABC All Lincoln transformers can be identified by the satin-copper case 3V' high, 2\" wide, and -?iY' over mounting feet. "'WO new Lincoln power supplies, one a "B" eliminator only, and the other a complete "ABC" power supply for A. C. tube sets, are contained in attractive brown crystaline steel shielding cases, long and narrow so that they may be placed in a radio set cabinet by the receiver itself. Each case is 13" long over two mounting feet, 3 1" wide, and 5V high, or 67" over the single 280 type tube used. Model 110 B power unit delivers from 180 to 200 volts at 50 to 60 m. a. from the "high voltage" binding post, and 22i, 90, and 135 volt* from other posts. From a special' post, a variable voltage of 22 1 to 9<J volts is available. This powerful eliminator will operate any set of ona to ten tubes, and is especially designed for high quality Lincoln audio amplifiers, its filtration being remarkably fine. The model 110-ABC unit furnishes just the same B voltages, plus 1.5, 2.25, and 5 volts for up to five 226 tubes, three 227 tubes, and four 1 12 A tubes. C voltage is obtained by suitable bias resistors in any A. C. set. Type HOB is priced at S36.00, and type 110-ABC at £39.00 retail list, fully guaranteed. Both will operate from any 105 to 120 volt, 60 cycle alternating current lamp socket. Lincoln will soon have ready a new receiver kit of wonderful tone, excellent selectivity and sensitivity — a set that brings DX right into the Lincoln offices in a steel building night after night. Send 2c for all data on new Lincoln products. LINCCLNRADIO CORPORATION 329 SOUTH WOOD ST. — CHICAGO ILLINOIS.