RADIO ABOARD THE CARNEGIE 



Transmitter ■ - -The Carnepie' s transmitter consisted 

 of a one-quarter kilowatt, crystal -controlled, master 

 oscillator, power amplifier outfit using a Western Elec- 

 tric 50-watt tube as crystal oscillator, a 250-watt first 

 amplifier, and a 250-watt second amplifier. The fre- 

 quency range of the transmitter was from 3000 to 18,000 

 kilocycles. 



Power supply to transmitter. --The power supply to 

 this transmitter was taken from a 3 -kilowatt, 500- cycle 

 motor generator run by the ship's batteries. The output 

 from the generator was run through suitable transform- 

 ers for filament, plate, and bias supplies. In the case of 

 the negative bias for the grids of the amplifier tubes 

 and in the case of the plate supply to the master oscilla- 

 tor, the transformer output was in each case rectified 

 by two UV217-A rectifier tubes and the rectified output 

 then filtered. 



Transmitting antenna. --The antenna used for trans- 

 mitting had a vertical part 130 feet long and a horizontal 

 top part 35 feet long, making a total of 165 feet. This 

 antenna was used with a ground, and the lead from the 

 transmitter to ground was about 12 feet, making a total 

 antenna ground length of 177 feet. A counterpoise also 

 was used on 18,000 kilocycles only and its length was 

 about 12 feet. 



Main receiver. — The receiver used for 3000- to 

 50,000-kilocycle reception was of U. S.Navy design and 

 consisted of a push-pull, screen-grid, radio -frequency 

 amplifier followed by a push-pull detector, the output 

 from which was put through a two- stage, audio -frequency 

 amplifier. 



Other receivers. - -A receiver made by the Radio 

 Engineering Laboratory was used as an emergency in 

 case of failure of the main set. This was a regenerative 

 detector, two-stage, audio -amplifier outfit that tuned 

 from 3000 to 20,000 kilocycles. 



A honeycomb-coil type receiver was used for long- 

 wave press and also for receiving broadcast programs. 



Special amplifier . --A two -stage, audio -frequency 

 amplifier provided with extra high negative bias on the 

 grids was used to work a 600-ohm relay for recording 

 time-signal beats on a photographic record. 



Operation of the transmitter. --The transmitter 

 operated well over its entire frequency range. The day- 

 light communication range was found to be about 4000 

 miles; the night range seemed to be not much over 8000 

 miles. These ranges are based on ability to handle 

 message traffic in a satisfactory manner with a signal 

 strength of at least 4 on a scale of 10. The daylight fre- 

 quencies were between 14,000 and 18,000 kilocycles; the 

 night frequencies were between 14,000 and 7000. The 

 night range was limited to 8000 miles by virtue of the 

 power available, but the daylight range of 4000 miles 

 was limited by power, frequency, and possibly the an- 

 tenna system. 



Operation of the receivers. --The main receiver 

 functioned very well, except for failure of audio -frequency 

 amplifying transformers, and this difficulty was reme- 

 died by filling the transformer bases with a special 

 compound protecting them from moist sea air. The 

 emergency receiver, except for calibration, exceeded 

 expectations. The honeycomb-coil receiver was not 



satisfactory on broadcast programs but worked well on 

 the long-wave code -reception. 



Operators . --One operator carried on all the radio 

 work but had other work also, one-half of his time being 

 spent in other than radio work. 



Recommendations for Future Work 



Transmitter. --The same type of transmitter could 

 well be used with the addition of another amplifier having 

 an output of at least one kilowatt. 



The frequency range of the transmitter should be 

 increased to include the 500-kilocycle ship standby fre- 

 quency for distress calls and to include, as a high-fre- 

 quency limit 50,000 kilocycles. 



Receiver. --The receiver as used was satisfactory, 

 with the exception of transformers, as already men- 

 tioned, and microphonic noises on the higher frequen- 

 cies. Both these faults should be taken care of in a 

 future receiver. Also a receiver covering the 500-kilo- 

 cycle ship standby frequency should be provided. 



Operators. --On a fully staffed expedition at least 

 three full-time operators should be employed, the rea- 

 son for this provision being that it is impossible for one 

 or two men to be sure of life and health over an extended 

 period, and in case of urgent need the presence of three 

 operators materially increases the chances of survival 

 of the whole expedition. Furthermore, to augment 

 knowledge of the behavior of high frequencies at sea a 

 continuous watch should be kept to make full use of the 

 opportunities offered. 



Lifeboat equipment. - -A low-powered transmitter 

 should be provided in each large lifeboat, with directions 

 for operating. This set should be foolproof, rugged, and 

 efficient. 



Routine of observations. — An entry in the radio log 

 should be made every hour for signal intensity on fre- 

 quencies such as 7000, 8000, 9000, 10,000, on up to 

 80,000 kilocycles; in other words, rim through the spec- 

 trum from 80,000 to about 7000 kilocycles, making a 

 note of signals and their strengths about every 1000 

 kilocyles. If two-way communication with experimental 

 stations is possible, additional data should be secured 

 every hour in this way on 7000, 14,000, and 28,000 kilo- 

 cycles. 



At least every hour, for about ten minutes, a watch 

 should be kept on 500 kilocycles, the ship'-s distress 

 frequency. While yachts are not required to keep such 

 a watch, one should be kept as often as possible as a 

 matter of cooperation with other ships. It is often the 

 case than an expedition is in a part of the ocean not fre- 

 quented by other ships on their regular courses and, be- 

 cause of this unique position, may be able to lend valu- 

 able assistance to a vessel driven from her course by 

 storm or accident. 



Special apparatus. --An oscillograph record of echo 

 signals at sea, together with a record of the direction of 

 arrival, would be a most valuable piece of research to 

 undertake. To do this an oscillograph, additional ampli- 

 fier equipment, and a directional receiving antenna 

 would be necessary. 



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