April 1936 Radio-Craft
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Craft,
published 1929 - 1953. All copyrights are hereby acknowledged.
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.
The Radio Month in Review
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.
Two radio devices used to track-down the
"shadow" - the direction finder and the oscilloscope.
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
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
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.
Some radio service equipment can be financed
under the F.H.A.
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.
Amateur radio maintained its reputation of
helping in time of emergency.
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
"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
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
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.
Major Williams uses short-wave radio for
announcing how to "loop the loop."
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
Mr. Insull is convinced and has convinced many of the small-station
owners that there is a real field for additional revenue by
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
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."
Babe Ruth was greeted by police guns!
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
The "Pack" radio transmitter used to announce
the results of an election.
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
Posted June 28, 2015