A hundred years ago this month, there might not have been a spy behind every tree. But there very well could have been German spies using those trees to conceal secret antennas, and the editors of Electrical Experimenter, in the September 1917 issue, were doing their public duty to warn Americans of the potential threat. Some possible secret spy antennas are shown here, along with the warning:

In preparing this article we have endeavored to show the unsuspecting
public how an enemy agent may either send or receive radio messages
by means of the most innocent appearing objects.

The Editors thought it best to give the article wide publicity, in order
that patriotic citizens may the better apprehend possible spies, who might be using secret aerials of the types illustrated.

The article is intended for public enlightenment, as well as for the
country’s safety.

According to the article, there could be a spy cleverly using your shade tree as an antenna, and it was a good idea to go out and check: “Have you examined your shade trees closely this summer? Don’t be surprised if you find a wire cleverly painted to match the bark on the tree and leading up to the various branches. It is readily possible for a persistent member of the enemy espionage squad to thus rig up a tree areial, and it is not necessary to travel very far to find a sufficiently large tree, which would serve as a framework for several hundred feet of insulated wire.”

A similar warning was warranted for those hanging their laundry out to dry: “If you live in the city (or even in the country) and have occasion to use a metal clothes-line of any appreciable size, it might pay you to closely scrutinize the supporting framework to see whether or not some alien enemy has been at work in an effort to use it for wireless communication purposes.”

These spy antennas could be anywhere, as shown in the illustration above.

Elsewhere in the same issue is the report of the U.S. Government blowing up the wireless tower at Shoreham, Long Island, erected at the cost of $200,000 by Nikola Tesla some twenty years earlier. The structure was no longer in use, but “during the past month several strangers had been seen lurking about the place.” Those lurking strangers could very well have been German spies, hanging around the 185 foot tower to use it as an antenna to contact Germany. Therefore, the Government blew it up.

Today, as a public service, we bring this illustration from the September 1942 issue of Popular Mechanics, which is just as relevant today as it was 75 years ago.

The drawing, which is clearly labeled “WRONG,” shows the housewife unplugging the radio by yanking on the cord.  The illustration in the lower left corner, shows the correct way, namely, by firmly grasping the plug.

The artist perfectly captures what appears to be a cavalier attitude on the woman’s part.  While she was probably otherwise the pinnacle of efficiency, the magazine pointed out that bad connections and broken power cords were the result of such treatment. It was a particularly bad idea in the case of the table radio, since it probably had a “curtain burner” cord, which would withstand few such jerks before causing the receiver to develop crackly noises or simply refuse to work. But even with plain line cords, then or now, the plug was easily damaged.

The magazine even noted that rubber-covered plugs were not plentiful, so this woman’s treatment of the strategic material was practically unpatriotic in wartime.

As far as we’re concerned, it’s still unpatriotic.  If you love your country, then you should unplug appliances by firmly grasping the plug.

Seventy-five years ago today, the September 7, 1942, issue of Broadcasting magazine included a supplement with the radio figures from the 1940 census, as well as a complete log of all U.S. broadcast stations as of 1942, and figures showing the numbers of radio retailers and sales figures. The map above shows the percentage of radio homes in 1940. Since there was a freeze on new stations during the War, and since no new radios were being produced, the issue provides an interesting snapshot of radio in the United States during the War years.

Massachussetts led the nation with 96.2% of its homes being equipped with a radio. Within that state, the county with the highest percentage of radio households was Norfolk County, with 98.1% of the households having at least one radio. The last place honors went to the State of Mississippi, with only 39.9% of homes having a radio, despite twelve broadcasting stations in the state. Within that state, the county with the lowest percentage of radio households was Issaquana County, where only 320 households out of 1779 had a radio, or only 18%.

Of Minnesota’s 728,359 households, 664,296 had at least one radio, for a percentage of 91.2. Lake of the Woods County had the lowest penetration of radio receivers, with 1150 radio households out of 1501 total, for a percentage of 76.6%. Minneapolis and St. Paul had very high percentages of radio households, 96.6% and 96.7% respectively. They were edged out, however, by Rochester, with 96.8% of the households having a radio. The other city included in the listing of cities over 25,000 was Duluth, with 95.7% of the households having a radio.

The station listing shown here reveals that during the War years, Minneapolis and St. Paul were served by seven stations. Both KSTP, 1500 kHz, and WCCO, 830 kHz, had 50,000 watt signals full time.

Three stations had 5000 watt signals during the daytime: WDGY on 1130 kHz, reduced its power to 500 watts at night, but the hours were determined by local time in Albuquerque, since it protected a station there. WLB, which later became KUOM, was daytime only, and also shared time on its 770 kHz frequency with WCAL in Northfield, an arrangement that continued in later decades. WTCN reduced its power on 1280 kHz to 1000 watts at night.

WLOL on 1330 kHz was licensed for 1000 watts, and WMIN ran 250 watts at 1400 kHz.

Duluth was listed as the home to KDAL on 610 kHz and WEBC on 1320 kHz. The other station serving the Twin Ports, WDSM, was licensed to Superior, Wisconsin, and appeared in the Wisconsin listings.

Cities with 250 watt stations included Albert Lea (KATE, 1450 kHz), Fergus Falls (KGDE, 1230 kHz, with 100 watts nighttime power), Mankato (KYSM, 1230), Moorhead (KVOX, 1340), Rochester (KROC, 1340), St. Cloud (KFAM, 1450), Virginia (WHLB, 1400), Willmar (KWLM, 1340), and Winona (KWNO, 1230).

Another station covering Minnesota but not listed was WDAY in Fargo, which corrected the oversight by purchasing two full-page ads, one in the Minnesota listing and another in the North Dakota section, pointing out that it had a large service area in both states, and including a story, that must have seemed just a bit risque in 1942, about a traveling soap salesman and a farmer’s daughter.

Seventy years ago this month, August 1947, the first issue of the British magazine Radio Constructor rolled off the presses, with the matshead bearing the names of editors Arthur C. Gee, G2UK, and W. Norman Stevens, G3AKA, and business manager C.W.C. Overland, G2ATV. According to the introductory editorial, postwar Britain was seeing a boom in short wave listening almost as big as the boom in broadcast listening after the first war.

The first of many receiver plans to be published by the magazine was a four tube (or three tubes, plus selenium rectifier) AC-DC broadcast set shown here. The first issue also carried a few theoretical articles, as well as the plans for one transmitter.

The magazine continued until September 1981, when the final issue was published.