Today marks the 80th anniversary of the attack on Pearl Harbor, December 7, 1941. Here are some of our previous posts covering this event:

• Broadcasting and Pearl Harbor.
• Pearl Harbor Radio Coverage.
• More Pearl Harbor Audio Clips.
• Keep indoors. Lie down. Turn off the lights. Turn on the radio.
• Remember Pearl Harbor, 1942

The clipping at left is from the December 20, 1941, issue of Radio Guide, the first to go to press after the attack. Very few blackouts were necessary in the Continental United States, but in the first days after Pearl Harbor, there were some fears that the Pacific Coast might be vulnerable to attack. So some radio stations went dark for a few nights in Washington, Oregon, and California. It probably wasn’t necessary after the 20th, but Radio Guide included this list of 50,000 watt stations throughout the country. If local stations went dark, this list could be consulted to find other stations carrying the same network programming.

Fifty years ago this month, the November 1971 issue of 73 magazine carried an article by Doug Gaines, W4AXE, detailing these plans for a three-element beam for 75 meters (3800 kHz). From his Florida QTH, he was tired of being outdone by stations in the Northeast, and decided to do a single-band entry into a DX contest on 75 meters. After various experiments, he decided to build a temporary 3-element Yagi, using his 125 foot tower, which at the time contained a 20 meter beam.

To manage this, he used the tower itself as the driven element, feeding it as shown with a gamma match, and with six quarter wave radials. The director and reflector consisted of vertical wires hanging from outriggers on the ends of the 20 meter beam, weighted down with bricks.

One incident involving the parisitic elements being tangled with the tower convinced him that the antenna should be turned slowly and only when necessary, but the system did work, and he reported 9 dB gain into Europe. The front-to-side ratio was 30 dB, and the front-to-back was 16 dB.

Seventy five years ago today, the August 12, 1946 issue of Life magazine carried this ad for the RCA model 56X and some variations. The set is a six-tube superhet covering the broadcast band, and retailed for $25.40 in its walnut plastic cabinet.  The same radio with the creamy ivory finish, model 56X2 sold for $27.50, and the 56X3 in a wooden cabinet had a list price of $33.95.

We’ve previously featured the 56X5, which added one shortwave band and earned the set the “12,000 Miler” moniker.  The shortwave set sold for $37.95.

You might not give much thought to the humble bicycle tire. But as shown in this cartoon, having good bicycle tires could mean the difference between life and death. A most unfortunate friendly fire incident was averted thanks to the hero’s bike being equipped with U.S. Royal tires, manufactured by the United States Rubber Co. This ad appeared 70 years ago this month in the March 1951 issue of Boys’ Life.

Seventy years ago this month, the December 1950 issue of Popular Mechanic showed how to put together these three crystal sets. All used the venerable (and still available) 1N34 diode. The first was the most basic set, but used a coil and variable capacitor for tuning.

The second featured greater selectivity, since in included two resonant circuits. For convenient tuning, the circuits used a ganged variable capacitor. The two L-C circuits were linked with with a “gimmick” capacitor consisting of two insulated wires twisted together. The article pointed out that a longer capacitor would result in greater volume, but a shorter wire would yield greater selectivity.

The final circuit was optimized for sensitivity, and would pull in the weak stations with two detectors running in a push-pull configuration.

All of the sets were said to have a range of about 40 miles.

If you’re thinking of recreating one of these circuits, see our crystal set parts page for ideas on tracking down the parts.

A century ago, after a long night of delivering presents, Santa relaxes. The ad appeared in Popular Science a hundred years ago this month, December 1920.

On this All Saints Day, we present “For All the Saints” (Sine Nomine):

Fifty years ago, the October-November 1970 issue of Science and Electronics showed how to put together, at a total parts cost of about $4, this combination continuity-tester/code practice oscillator.

The circuit was dubbed by the author the “CON-TEST,” since it was first and foremost a continuity tester. But as the photo above shows, it was very suitable for use as a code practice oscillator.

The choice of transistor was not critical, but the author used a 2N170 for the audio oscillator, along with a 2N174 audio amplifier to produce some room-filling volume.