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April 1936 Radio-Craft[Table of Contents]
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Radio-Craft was published from 1929 through 1953. All copyrights are hereby acknowledged. See all articles from Radio-Craft.
Did you know that some radio service equipment can be financed by the Federal Housing Administration (FHA)? That's right, if your business needs a new tube tester or maybe an oscilloscope, Uncle Sam is there to help. That was in 1936, anyway, per this Radio-Craft news blurb. Today, of course, the FHA no longer makes loans for business equipment - the Small Business Administration (SBA) takes care of that. Nowadays the FHA restricts itself to home loans - including to illegal residents and otherwise traditionally unqualified. Also reported, among lots of other interesting stuff, is some early instances of RFI (radio frequency interference) emanating from hospital equipment.
Radio is now such a vast and diversified art it becomes necessary to make a general survey of important monthly developments. Radio-Craft analyzes these developments and presents a review of those items which interest all.
Radio "Shadow" Unmasked at Last
Last month the answer was found to a question which for some time has stumped radio operators, short-wave listeners and the entire radio profession.
As some readers may know, a mysterious type of radio interference in the form of a low-pitched hum similar to a 60-cycle line hum has been interrupting radio communication on certain short wavelengths, especially between the frequencies of 11,000 and 20,000 kilocycles. The hum has been heard irregularly and it apparently changed in frequency from time to time.
This mysterious "shadow" as it has been affectionately (or not so affectionately) called, has puzzled some of the best-known engineers in the radio industry and become so important during the past 6 months that RCA Communications, Inc., spent many hours making "fingerprints" of its tone, wavelength, waveform, and direction of emanation.
Finally, the "shadow" was unmasked, last month (after many possible sources were tracked down) by the U.S. Navy!
The mysterious hum which was reported from all parts of the U.S., Honolulu, Nova Scotia, Puerto Rico and the Canal Zone has been traced to the high-frequency vacuum tubes used by hospitals and doctors in certain medical treatments. The findings were turned over to the F.C.C. for further consideration. It is stated that proper shielding will eliminate the "shadow."
Photo-Cells Give Telephone Time Service
The Post Office Department in Berlin, Germany, made known last month that it is testing a new apparatus which automatically announces the time to all telephone subscribers. The device consists of a drum on which narrow tone-film strips are placed so that they cover one-half of the drum. Twenty-four tonebands are recorded, one for each hour of the day, and 6 strips are recorded for the minutes. The tonebands are scanned by 2 photoelectric cells (one for the hours, and the other for the minutes) so that every reporting of the minute is preceded by a reporting of the hour. The time is announced once every 4 seconds, thus 14 times in each minute. A few seconds before the minute is over the machine is cut off and a buzzer switched on for 3 seconds, so that the end of a minute can be marked exactly.
This represents a new service and a unique application of electronic devices.
Service Equipment Approved for F.H.A. Loans
Service Men will be interested to learn that certain types of servicing equipment were approved, last month, for financing by the Federal Housing Administration!
The Precision Apparatus Co. was among the first to have its units approved for financing under the above plan. Analyzers and tube testers made by this company are among the servicing components included.
Under this plan, dealers and Service Men can buy their equipment and pay for it over an extended period, just as repairs on homes, buildings, etc., are being financed by this Federal Administration.
Verifications to be Discontinued
Of interest to the DX fan is the decision made last month, by two well-known operators of radio broadcast transmitters, to discontinue sending out the usual verifications of reception.
It is to be regretted that the Westinghouse Company which operates W8XK and W1XK short-wave stations, and the British Broadcasting Co. which operates the short-wave transmitters in England, found it necessary to discontinue this service to their listeners in far-off lands.
The announcement of the Westinghouse Co., explained that newspapers and magazines now carry listings of short-wave transmitters, their frequencies, and program schedules. The increasing volume of mail, it added, also makes acknowledgment impracticable.
Amateur Radio Saves Infant
Amateur radio again came through nobly last month, in an emergency. On a small island in the Pacific Ocean, 75 miles out from Los Angeles, a tiny four-months-old girl was ill and in need of medical aid. The only communication from the island, which is known as San Nicolas Island, to the mainland is by means of an amateur radio station - W6JLF - operated by I. P. Elliot.
Elliot made contact with another amateur at Redondo Beach who called the local police. The latter notified the Los Angeles police and the Coast Guard-and by the time the police reached a doctor, a Coast Guard Patrol Boat was ready to sail.
Before morning, the boat, carrying the doctor, hove-to on the lee side of desolate San Nicolas Island and another mark was chalked up on the already enviable record established by amateurs.
"Radio Fading" and Sun Glow
Bright hydrogen eruptions from the sun corresponded with the major radio fade-outs during this past year, according to a statement made last month by Dr. R. S. Richardson of the Mount Wilson Observatory.
Four remarkable fade-outs of radio transmission were noticed at intervals of about 54 days and it was suggested by Dr. Richardson that some form of unusual solar activity might be responsible. Spectro-heliograms (in other words - special photos) of the last two fading periods which lasted about 15 minutes each, showed in each case a strong eruption of glowing hydrogen - known as a "flocculus." Dr. Richardson based his statement on these records.
The careful study of such phenomena will eventually result in much better knowledge of radio transmission.
Radio Reports Aerial Maneuvers
The short-range characteristics of ultra-high frequencies in the neighborhood of 35 mcs. have just been put to a new and interesting use by the well-known flier, Major Al Williams.
The installation, which was completed last month, is the first of its kind to be used in an airplane. It consists of a 5-watt transmitter and receiver installed in the plane, with similar equipment located on the ground.
Major Williams uses this set-up to demonstrate difficult aerial maneuvers to aviation students and spectators, at various air fields. He converses continually with an announcer on the ground, explaining his movements.
Insull Buying Radio Stations?
According to a report received last month, Samuel Insull - one- time utilities magnate - is starting a new venture called the Affiliated Broadcasting Co. with which he hopes to band together some 26 low-power broadcast stations in Illinois, Wisconsin and Indiana.
Mr. Insull is convinced and has convinced many of the small-station owners that there is a real field for additional revenue by banding together.
However, an inquiry addressed to the Federal Communications Commission was answered very definitely that they (the F.C.C.) had no such information! /p>
Among stations known to have been approached by the ABC are WCLS in Joliet and WWAE in Hammond - both have a power of 100 watts.
Radio "Signal 32" Nabs Babe Ruth
An amusing incident - and one which shows just how efficient the police-radio systems in large cities can be - took place last month, and involved no less a celebrity than Babe Ruth, baseball's "King of the Swat."
It seems that the Babe struck another car while driving home from Long Island, N.Y.; the damage was slight and he decided to proceed on his way.
However, the owner of the car which was hit thought differently, and before Mr. Ruth had crossed the Queensboro Bridge across the East River, he was greeted by an officer with a high-powered rifle. It seems that the police, not knowing who they were chasing sent out signal "32" meaning that the quarry might be dangerous!
The incident was settled peacefully.
"Pack" Transmitter Reports Ballot
The engineering staff of station WLW found a new use for the portable "pack" transmitter which they designed and built a short time ago, in the experiment conducted last month in Cincinnati with the "proportional representation" method of balloting.
This suggests a new use to which such short-range transmitters will, no doubt, be put (F.C.C. permitting!) by other broadcast stations on similar occasions.
The transmitter, carried on the back of an announcer can be taken anywhere (where it is not possible to move the ordinary "mike" and line amplifier) thus facilitating the reporting of such events. The signals from the pack transmitter can be picked up at any convenient location by a receiver and then carried over land lines to the station. While the use of portable transmitters is not new, this application is certainly a new and novel one!
"Check Valve" Reduces "Static"
Late last month, the American Radio Relay League announced a new radio device, which could be attached to the intermediate-frequency amplifier of any broadcast or short-wave superhet.
This device, which was described as a "balancer circuit," reduces to a great extent the interference caused by auto ignition systems, refrigerators and other forms of man-made static and will, to some extent reduce natural static, though it is not a "static eliminator."
Mr. James J. Lamb who designed the new unit stated: "The general principle comprises one tube paralleling a tube in the receiver's I.F. amplifier, followed by a rectifier. The rectified noise currents are fed back through a circuit and applied to a previous tube in the receiver to block or render that tube inoperative for the duration of the noise impulse.
"The period the device is active may be so small that the ear does not perceive any change in the program quality."
In other words, this device is a special type of automatic volume control!
Posted June 28, 2015