Author Archives: clem.law@usa.net

RCA 56X5 “12,000 Miler” from 1946

RCA56X5Seventy years ago, this day’s issue of Life Magazine, March 4, 1946, carried this ad for the RCA model 56X5. The “12,000 Miler” covered standard broadcast and short wave with six tubes, including the rectifier.

I’ve always considered this set to be quite handsome, and it’s also a good performer on both AM and shortwave.  A nice example can be found at the Radio Attic Archives.  And you can see the set in action pulling in some Chicago stations at YouTube.

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1941 Bamboo Beam

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Seventy-five years ago, the March 1941 issue of Radio and Television carried the plans for this two-element 20 meter beam in use by R.M. Blanchard, W4FIC. The antenna was constructed of bamboo, with the driven element and director consisting of wires taped to the bamboo. The rotor consisted of a bicycle chain connected to ropes, adjusted on the ground as shown in the diagram below.

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Mr. Blanchard reported that the antenna performed well, logging contacts with the Philipines, Guam, and Little America. In addition, the antenna was used for numerous schedules with the Hawaiian Islands.

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RCA Station Allocator, 1941

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Seventy-five years ago, it was a big month for radio servicemen.  The new North American Radio Broadcasting Agreement called for most North American broadcast stations to shift frequencies on March 29, 1941.  The trade press was abuzz with how this could be of benefit to servicemen, who would be called upon to reset the pushbuttons of millions of radios.

The undoubtedly caused a bit of trouble for some shops, since resetting the button really required the station to be on the air on the new channel to make sure the job was done right.  RCA came out with the piece of equipment shown here, in an ad in the March 1941 issue of Radio Today.  For $17.50, the shop could buy the RCA Station Allocator.  It consisted of a signal source with several buttons.  It would then put out a test signal on the given frequency, making short work of the adjustment of the customer’s set.

More information on this piece of test equipment can be found at RadioMuseum.org.  The set was portable, and could run either on AC power or internal batteries, making the house call for this adjustment quite simple.

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1941 Popular Science Radio-Phono Combo

1941MarPSSeventy-five years ago, the thrifty radio enthusiast could construct this radio-phono console for only $27.50, following the plans in the March 1941 issue of Popular Science.  Even though the set contained only two tubes, it reportedly boasted all of the features of an eight-tube set.

The receiver consisted of a 12B8GT regenerative detector.  The article noted that the regeneration control could be left at the same setting throughout the entire broadcast band, without the set breaking into an annoying squeal as the owner tuned from one end of the band to the other.

The amplifier for both radio and phono was a 32L7GT feeding a 6-inch speaker.  The dual tube also contained the rectifier, which allowed the transformerless set to run from household power.  The filaments were wired in series, along with a 220 ohm resistor.1941MarPS3

The $27.50 price tag quoted in the article included everything, including a pre-made cabinet, the phonograph motor, and pickup.

 

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Happy Leap Day!

1908 Leap Year postcard. Wikipedia image.

Today is leap day. In order to accomodate the U.S. presidential election and the Summer Olympics, the years in which those events take place require an extra day, which is added on February 29. These events take place in years evenly divisible by four (2016/4 = 504), and for this reason, Pope Gregory decreed in 1582 that such years would contain 366 days, rather than the typical 365. The first leap year took place in 1584. Even though there was no presidential election or Summer Olympics that year, the new system showed incredible foresight.

The addition of a leap year also keeps the calendar in sync with the Earth’s orbit around the sun, which takes approximately 365-1/4 days. Without the modification to the calendar, the seasons would shift by about one day every four years.

However, the Earth’s period of orbit around the sun is not exactly 365-1/4 days. It is actually slightly more, but because of the effect of the Earth’s precession, it appears from the point of view of an observer on Earth to be slightly less, namely 365.24219879 days.

To get things properly in sync, a few more tweaks had to be made. Therefore, years divisible by 100 (which are divisible by 4, and would normally be leap years) are not leap years. Therefore, 1900 consisted of 365 days, and there was no February 29, 1900.

This correction by itself would make the average year measure 365 + 1/4 – 1/100 = 365.24 days. However, to refine the formula even more, another exception is made. Years divisible by 400 are leap years, even though they are divisible by 100. Therefore, 2000 was a leap year, and there was a February 29, 2000.

With this added factor, the average year length is now 365 + 1/4 – 1/100 + 1/400 = 365.2425 days, which is only 0.0003013 days more than the actual length of the year. This means that it will take 3319 years for the calendar to be off by only a single day. But that seems to be an adequate distance to kick the can, and our descendants can deal with the problem then.

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Hallicrafters S-40, 1946

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Just six months after V-J day, Hallicrafters had the S-40 general coverage receiver on the market, as shown by this ad from the February 1946 issue of Radio Craft.




1975 QSL Card

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I got a nice surprise in the form of an e-mail from Mark, AE6RT, formerly WN0OWP. He had googled his old call sign, and came across my Old QSL page, where I have listed the QSL cards I have from my first days as a ham in the 1970’s.

He included the photos of my card, which I sent to him in 1975 after a 40 meter CW QSO.  Of course, I still had his card and sent him a scan of it as well.

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Boy Scout Broadcasts, 1941

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Shown here are the Scouts and Scoutmaster of Troop 3, Bloomington, Illinois, presenting a radio broadcast over station WJBC, Bloomington-Normal Illinois. The photo appeared in the February 1941 issue of Scouting magazine, along with pointers for troops and local councils to put on Scout broadcasts. The article stressed that putting on a broadcast was not a small undertaking, and would require a great deal of effort by the Scouts and Scouters involved. It did note, however, that stations could be receptive to the idea: “Local stations in all parts of the country make a practice of devoting a certain amount of their time on the air to educational sustaining programs. It is generally very easy therefore, for Boy Scouts to secure free time on the air.”

The National Council of the BSA made available scripts for use by local units, and the U.S. Office of Education made available additional scripts that might be appropriate for Scout programs.

Because of the scope of such a project, the article recommended that such efforts were probably best accomplished by local councils, rather than individual troops. In any event, the article stressed that approval from the council must be obtained prior to approaching any radio station asking for air time.

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RCA “Foreign Correspondent” Model 14-X Shortwave

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75 years ago, this date’s issue of Life Magazine, February 24, 1941, carried this ad for the RCA Victor “Foreign Correspondent,” also known as RCA model number 14-X.  As the name implies, this set received shortwave as well as standard broadcast, and as the ad points out, the shortwave band was s-p-r-e-a-d for easy tuning.  The set covered 9.5-12 MHz, meaning that it did have reasonably easy tuning of the popular 31 and 25 meter bands.  In the evenings, the set probably did a good job of pulling in war news from Europe.

The set had a price tag of only $14.95, and looks like it was a fairly good performer for the price.  The set was a basic “All American Five,” with a tube lineup of 12SA7 12SK7 12SQ7 50L6GT 35Z5GT.  It had provision for an external antenna.  The limited shortwave frequency coverage probably did make it considerably easier to tune those bands.

A nicely preserved version can be found at the Radio Attic Archives.