Monthly Archives: March 2017

1932 Church Group Hearing Aid

Group hearing aid receiver in use.

Today, almost every auditorium of any description is wired for sound, and we take for granted that someone will turn on the PA, and we’ll be able to hear what’s going on through the ubiquitous speakers.

But this hasn’t always been the case. We take the presence of the sound system for granted. But until the early 20th century, there was an absolute prerequisite for orators of any type: They needed to have a loud voice in order to be heard.

This was particularly true of churches. There was one qualification for ministers that was even more important then their theological bona fides: They had to be loud, since their sermon had to fill the sanctuary on its own power, without the aid of any electrical amplification.

This began to change in the 1920’s and 1930’s, as the “sound man” became an important player in the field of electronics. Wiring halls of any type for sound became a lucrative profession. And with the advent of the microphone, amplifier, and loudspeaker, the sheer volume of the preacher’s voice became less and less of an issue.

A related issue was addressed by an article appearing 85 years ago this month in the March 1932 issue of Radio News. Electronic amplification could solve another problem, namely allowing those with poor hearing to fully participate in church services and other public events. Personal hearing aids worked well for conversation with another person nearby. But they were largely useless for picking up a speaker at the other end of a large auditorium. For that reason, churches and other public venues were beginning to wire what the article called “group hearing aids,” or what we would today call assistive listening devices.

As seen from the schematic here, the circuit is quite straightforward. A microphone is placed near the pulpit, is amplified, and is then fed to telephone receivers with individual volume controls.

The article concluded by noting that the date was not far distant when those with defective hearing would be able to walk confidently into any hall or meeting place knowing that provision had been made for them to participate fully in one more phase of well-rounded living.

Modern assistive listening devices (ALD’s) are typically wireless, most frequently operating below the FM broadcast band at 72-76 MHz. You can read more about modern systems at my ALD receiver page.

FCC Approves Two New Ham Bands

FCC Approves Two New Amateur Bands

World War II Radio Heroes: Letters of Compassion, by Lisa L. Spahr

We previously reviewed the book World War II Radio Heroes: Letters of Compassion by Lisa L. Spahr. The book collects numerous letters from shortwave listeners to families of World War II POW’s held by the Germans and Japanese. Names of prisoners were broadcast by Berlin and Tokyo radio, and these listeners contacted their families to reassure them that their loved ones were alive and well.

The Kindle edition is currently being offered at a sale price, and it’s well worth downloading this interesting book. You can do so at the link below.

Canadian POW Sgt. Brian Hodkinson

Then 16 year old Hodgkinson at the CKY microphone, circa 1930. Manitoba Historical Society photo.

This postcard from RCAF prisoner of war Sgt. Brian Hodkinson appeared 75 years ago this month in the March 1942 issue of CKY’s program guide, Manitoba Calling. Prior to the war, Hodkinson was an announcer at the Winnipeg station. With the outbreak of war, he enlisted in the air force, and on one of his first missions over France, he was shot down and held prisoner for the duration of the war.

This card was sent to a friend in WInnipeg, Dr. John Toole, and reports that the Germans were treating him well. He requested “cigs. & chocolate, etc.” via the Canadian Red Cross. Dr. Toole shared the card with the radio station.

Hodgkinson spoke little of the war years, but after much prodding by friends, he did put his memoirs on paper. After the war, Hodgkinson moved to the United States and was for many years a newscaster and commentator at WHK, WERE, and WDOK in Cleveland.

After his death, a manuscript for a book was found. It was published in Canada in 2000 as Spitfire Down.

The book is a fascinating look not only at Hodgkinson’s time as a POW, but also at his training. The RCAF had to get pilots in the air as fast as possible, and the training was intense. Hodgkinson recounts that he got lost on his first solo cross country flight, which was supposed to be from Ottawa to Kingston. He got lost, and finally spotted an airport, which turned out to be Montreal. Low on fuel and daylight, he landed and called his base for instructions. After some discussion, he was told to return to Ottawa the next day. He got lost again, and once again he landed at an unfamiliar airport. When a friendly airport worker came out to meet the plane, he asked where he was, and was told that he had landed in Ogdenburg, New York.

Since the United States was still neutral, Hodgkinson realized that his navigation blunder would result in his spending the duration of the war in an American internment camp. So he asked which way it was to Ottawa, and promptly flew north.

Despite these false starts, Hodgkinson was quickly sent to England, and on one of his first missions over France, he was shot down. Most of the book recounts his experiences in a hospital in France, and then in prison camps in Germany.

One feature that stood out was the fluent English speakers that Hodgkinson encountered. While he and his other prisoners in the hospital in France noted that before long they would be speaking a mixture of three languages, there were English speakers among his captors. The first that he encountered was the doctor who oversaw the treatment of his injuries, Dr. Rudy Meinhoff. Hodgkinson was surprised to hear the doctor address him with a clearly American accent. It had turned out that the German doctor had practiced in Milwaukee before the war, and had even attended a medical conference in Winnipeg.

Hodgkinson (front row, center) along with fellow prisoners, 4 New Zealander and 1 English, 1944. Manitoba Calling, Apr. 1944.

Hodgkinson (front row, center) along with fellow prisoners, 4 New Zealander and 1 English. Manitoba Calling, Apr. 1944.

And upon his transfer to the German prison camp, Hodgkinson’s interrogator was Wehrmacht intelligence officer Col. Gustave Metterling, who also surprised Hodgkinson with an American accented English. Before the war, Metterling had lived in New York, where he made a career of selling forged oil paintings, often made to order by wealthy buyers.

The book is not available in the United States, but used copies are available at a reasonable price on Amazon. In Canada, it’s also available at Amazon.ca.

The book is a fascinating look at the war by one who had to sit most of it out. According to Worldcat, relatively few libraries, American or Canadian, have a copy. But it is apparently still in print from its Canadian publisher, and reasonably priced copies are available on Amazon. It’s definitely worth seeking out.

Margaret Donahue, First Woman Licensed as Commercial Radio Operator

We previously wrote about Margaret Donahue of Boston, who was reportedly the first woman to receive her first class commercial radio operator’s license. This fact was reported a hundred years ago today in this clipping from the March 29, 1917, edition of the Bridgeport (CT) Evening Farmer.

She was at that time employed as a wire telegraph operator in Boston. With her new credential, she had volunteered her service to her country in the upcoming war.

POLICALARM and MONITORADIO Receivers, 1952

Sixty five years ago this month, the March 1952 issue of FM-TV magazine carried this ad from the Radio Apparatus Corporation of Indianapolis, Indiana, for its monitor receivers, sold under the POLICALARM and MONITORADIO trademarks. Five models were available. For the 30-50 and 152-163 MHz FM public service bands, both 6 volt and 115 volt models were available. For the AM aircraft band, a 115 volt model was available, covering 108-132 MHz. All were continuously tunable.

The sets were marketed to police and public service agencies for two purposes. First, “channel neighbors are monitored for pertinent information.” In addition, staff could have receivers in their homes or vehicles to be “constantly alert to communications while driving on or off duty, or at home.”

The ad even carried a testimonial from the city manager of Winchester, Virginia, who thought “you have a receiver that is well built, and I see no reason why it should not be in demand by all public works departments that have a transmitter available.”

There’s no indication that the City of Winchester actually bought one, but the city manager said he could see no reason why other cities wouldn’t want one. The ad did note that the receivers were in use by hundreds of municipalities “from Boston, Mass., to Alhambra, Cal.”

The 120 volt units appear to use the “POLICALARM” name, while the mobile units were “MONITORADIO.” An example of one of the 120 volt units can be found at this eBay image. A picture of the 120 volt Monitoradio AR-1 aircraft receiver can be found at The Radio Museum. The set pictured is one of the 6 volt models, all of which had the same styling. The units designed for household power resemble a broadcast receiver, with Bakelite cabinets.

Radio Apparatus Corporation later became part of Regency.

Preparing for the End of Civilian Radio Production

By orders of the War Production Board, manufacturing of civilian radio receivers ended on April 22, 1942, for the duration of the war. Even before this was announced on March 7, radio servicemen knew that at the very least, there would be shortages. When the ban was announced, they knew it was up to them to keep America’s radios in operation for their vital war information and for morale.

When the ban was announced, servicemen knew that it was time to double down, and they were reminded by advertisements such as this one, which appeared in the March 1942 issue of Service magazine. The ad was from the John F. Rider company, publisher of service manuals. These manuals contained diagrams and service information of virtually every set ever manufactured, and this data would prove invaluable for the radio servicemen tasked with keeping the nation’s radios in operation for the duration.

1967 One Tube CW Transmitter

Fifty years ago, the March 1967 issue of Electronics Illustrated carried the plans for this simple 40 meter CW transmitter. The set ran directly off AC power, with a transformer supplying 120 volts B+, rectified through two silicon diodes, as well as 6 volts for the filament of the single 6AQ5A tube. It ran 15 watts input power, with output of about six watts.

The author, James B. White, W5LET, noted that the transmitter would be a good first rig for the Novice, as a perfect second rig for the oldtimer, or tucked away on the corner of the operating table for use as a standby transmitter.

The parts count was kept down by omitting a variable capacitor for tuning the plate circuit to resonance. Instead, the tube’s plate-to-cathode capacitance was tuned against the plate coil, which was adjusted with a slug-tuned core. A neon lamp was used as the RF indicator to assist with the tuning process and to visually monitor sending.

The rig got out, and the author reported that his first CQ from Louisiana was answered immediately from the Midwest. During its first hour on the air, the author worked both coasts.

1967 Outlet Tester

If you do any electrical work around the house, or even if you don’t, and you want to make sure the electrician did things right, you really ought to have an inexpensive outlet tester like the ones shown here. You’ll be able to tell at a glance whether the outlet is wired correctly, or if there’s some invisible fault. Those errors could include the polarity being reversed, either the neutral or the hot not being hooked up, or the absence of a ground connection. The one shown here is available on Amazon, and they can be had at low cost at any hardware store.

But fifty years ago, they weren’t so readily available, and the home handyman might consider making his own. The plans were shown in the March 1967 issue of Popular Mechanics. As you can see, the device is quite simple. If you want to make your own, here’s the schematic:

Fire Island Light Ship Distance Measuring Apparatus

A hundred years ago this month, the March 1917 issue of the Wireless Age carried a description of the distance measuring apparatus in use by the Fire Island Light Ship, The light vessel, located in New York Harbor, was equipped with apparatus which would allow an approaching ship to accurately measure its distance from the station.

To do this, the light vessel used a radio transmitter (call sign NLS) and a 1000 pound submarine bell. The bell would strike a sequence. At a precise time after the first strike of the bell, the radio would send a series of dots. An approaching ship would hear the bell, followed by the radio signal. The difference in time between these signals would correspond to the distance travelled by the two signals.

The announcement explained that the best way to copy the signal would be with headphones connected so that the wireless signal was played in one ear, with the other receiver connected to the submarine bell detector. It would then be an easy matter to distinguish the signals. Since the dots coming from the radio transmitter followed a carefully controlled pattern, it was necessary only to count the dots heard prior to hearing the bell.

The radio operated on a wavelength of 600 meters (500 kHz), and ran continuously during thick weather, and during the first 15 minutes of the hour during clear weather.

The vessel, Lightship LV-68, was built in 1897 at a cost of almost $75,000, and had a length of 122 feet. Each of its masts held a 100 candlepower electric lamp. It also carried a 12 inch steam whistle in addition to the bell. It remained in operation until 1930.

References

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