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84 RADIO BROADCAST May Standard Frequency Signals STANDARD FREQUENCY sig- nals from the Bureau of Standards have been used by amateurs, laboratories and experimenters for several years. These signals are sent out about the 2oth of each month and begin at 10:00 p. M. E. S. T. On May 21, signals will be sent on frequencies of 650 to 1500 kc. and should serve as calibrating signals for wavemeters and oscillators working in the broadcast range of frequencies. The signals begin at 10:00 and con- tinue until 11: 3 2 p. M. They consist of slightly modulated c.w. telegraph and take place as follows: at 10:00 a general call will be sent con- sisting of the statement of the frequency, the call letters of the Bureau station, wwv, then a series of very long dashes and call signals on the stated frequency, then the statement of the frequency transmitted and the next frequency. These signals require about 8 minutes, and are repeated on the next frequency after a lapse of four min- utes during which the transmitter is adjusted. Anyone within 500 to 1000 miles of Washing- ton, D. C. should be able to use the signals pro- vided he has a receiver in which the detector can be made to oscillate, a Roberts or Lab. Circuit, for example. The receiver should be adjusted to the approximate frequency, the detector oscillat- ing, with a pair of receivers in the output of the amplifier which may be one or two stages. At the proper time, indicated below, the receiver should be adjusted until wwv's signals are heard beating with the oscillations of the local detector circuit. This circuit should then be adjusted to zero beat with wwv, and a wavemeter, preferably an oscillating tube attached to a coil and con- denser, is tuned also to zero beat. The wave- meter and the receiver and wwv are then all on the same frequency. A record should be kept of the frequency and the setting of the wave- meter condenser as well as that of the receiver in case it is desired to calibrate the receiver. The schedule follows: KILOCYCLES 64,000 to 56,000 3,5 50 to 3,500 2,000 to 1,715 METERS 4.69 to 5.35 84.5 to 85.7 i 50.0 to 175.0 GENERAL ORDER NO. 24 of Short-Ware the Federal Radio Commis- "Nfitt sion opens up a new telegraph band for amateurs between 28,000 and 30,000 kilocycles, or 9.99 to 10.71 meters. It also defines an amateur station as one "operated by a person interested in radio tech- nique solely with a personal aim and without pecuniary interest." It also makes slight revisions in the telephone bands open to amateur traffic. Radio telephones are now permitted to operate in these bands: NEW RCA AIRPLANE SET On March 173 six-passenger Stinson-Detroiter monoplane left Curtiss Field on a coast-to-coast flight bearing five passengers and considerable radio equipment. A photograph of some of this apparatus, built by the R.C.A. is shown here. By the time this appears, many amateurs will have worked the plane whose radio gear was under the key of H. C. Leuteritz, and which was licensed to transmit on 120 meters using the call letters2XBK. Attempts were made to get into contact with the plane from the RADIO BROADCAST magazine station, 2 GY, but by the time we got the receiver wound up to operate on the rather unusual wave- length of 120 meters, the plane was apparently too far away. We heard several commercial sta- tions calling her, and found a lot of interesting things going on between 100 and 200 meters. For example the coast guard boats using Western Electric radio equipment could be heard all up and down the coast hammering out information about the rum fleet—probably. The stuff was in code. Not long ago we got up at 5 A. M. E. S. T. and hammered out a CQ on our 4O-meter station, 2 EJ (See our April, 1927, issue). Two stations came back at once, and on about the same fre- quency, one fairly loud and the other quite weak. We clicked with the louder of the two asking the weaker to QRX for a few minutes. The louder sta- tion turned out to be in Colorado and very glad to be QSO the east coast because he was using low power. After some conversation we signed off and gave the weaker station a call, not know- ing, of course, whether he was still standing-by or not. Sure enough he came back, and he too was most anxious to chat. He was using 180 volts on a 112 type tube and had a call which indicated he was in Oklahoma. A few days ago we received a card from this operator stating that he was on a boat in San Francisco harbor on the night in question using about i watt input to his 112, and not having a better one used his Oklahoma call. The distance from San Francisco to Garden City is something over 3000 miles which is not bad for an input of i watt. The following letter from M. W. Pilpel, London, England, relates the success he has had with a transmitter described in RADIO BROAD- CAST. Mr. Pilpel's call letters are 6 PP and his wavelength is about 45 meters. He states that he is on the air every evening up to about 7 p. m E. S. T. In this letter "NC" refers to a station in Canada, "AQ" to Iraq, "AS" to Siberia and "FM" to Morocco. "I feel that I must write and tell about the splendid results 1 have obtained with a set described in your paper. The set concerned is the " B Battery Trans- mitter" described in your November, 1926, issue. I built this set almost exactly as your diagram, but used o.ooo3-mfd. condensers in- stead of o.ooo25-mfd., and a grid leak var- iable from 1500 to 100,000 ohms instead of a fixed lo.ooo-ohm one. The plate supply is from accumulators, 180 volts, and the tube used is a Marconi DE5, more or less the Eng- lish equivalent to your ZOI-A. The antenna is a small cage with four wires and is only 15 feet long and 20 feet high. The direct ground is used. Now for the results, with an input of 27 m/a (4.8 watts) or less I have succeeded in JUNE, 1928 working four continents. Actually the best distance worked is Manoa, Pennsylvania where my friend NU-3PF gave me R2- 3 during a QSO lasting nearly ij hours. Two first dis- trict NUs have also been worked. Then, NC (R2-3), AQ (Ri!!) AS (R 3 ), and FM (R6) outside Europe. Only three European coun- tries possessing hams have not been worked yet, Rumania, Switzerland and Lithuania, all others have been worked on more than one occasion. LPJ at Spitzbergen gave me R 3 in daylight, and OIK, when 400 miles south of Greenland, R;. The best miles-per-watt is over 900, ED 7HJ of Bornholm, Denmark, 750 miles away giving me R4 when using 0.8 watts. I attribute these results chiefly to the steadiness of the note emitted by the set and must congratulate you on bringing this excel- lent little "perker" to general notice and describing it so well." Recent Interesting Contemporary Articles EACH MONTH we look through the welter of radio magazines and papers that come into the office. Occasion- ally, we read some of them. QST, for example, disappears from the office the moment it comes from the mail room and does not come back until whoever took it has perused every word. Then someone else grabs it. Experimental Wire- less and Wireless Engineer (England) suffers the same experience. The rest of them from a tech- nician's standpoint, seem mediocre, a sad fact true even of the Proceedings of the I. R. E. at times. The following recent articles are worth reading. TITLE MAGAZINE DATE Double Detection Detectors and Screen-Grid Amplifiers QST March Directional Properties of An- tennas QST March The Photoelectric Cell Radio February Frequency Stabilization on Short Waves by Quartz Crystals L'Onde Electrique January Theory of the Antenna Wireless Exper- imenter March A Radio-Frequency Oscillator /. R. E. February Theory of Power Amplification I. R. E. February Ideals of the Engineer by John J. Carty Journal, A. 1. E. E. March Use of Very High Voltage in Vacuum Tubes by W. D. Coolidge journal, A. 1. E. E. March IN SPITE of the fact that Another Useful OUT friend C. T. Burke of the Publication General Radio Experimenter catches us up, publicly, whenever we make a mistake, we still believe that every serious radio thinker should be on the list of those getting this excellent trade publica- tion. A similar sheet has arrived in the Laboratory. It is called the Aerovox Research Worker and is published by the Aerovox Wireless Corporation, 70 Washington Street, Brooklyn, New York. It, too, is worth having regularly. In our list of "Manufacturers' Booklets Available," regularly listed in the back advertising pages of this magazine this publication is listed as No. 120. ANYONE WANTING a free Radio School ticket to the Radio Institute Scholarships of America should get in touch with J. V. Maresca, Room 1889, Hotel Roosevelt, New York. He has charge of applications for two scholarships offered by the Veteran Wireless Operators' Association and the two offered by A. H. Grebe. Awards will be made to those American born youths over eighteen years of age who write the best letters of essays on "Why the American Merchant Marine Needs Perfect Wireless Com- munication." — KEITH HENNEY.