Seventy years ago, the March 1956 issue of Popular Electronics showed how to build this compact transmitter for the 40 meter band. It was housed in a sandwich box, available at the local dime store. The author, Elton Stolberg, W7OUV, did warn that the container was fragile when it came to drilling the required holes.  A single 6AQ5 served as a crystal oscillator, with about 16 watts input power.  Pin jacks were used for the coil socket, and cut-off finishing nails were used on the coil itself for the plug.  The transmitter was designed for 40 meters, but extra room for an 80-meter coil was included.

The author reported that he had used the radio, with a vibrator power supply, on Field Day, resulting in 53 contacts with seven states, plus Hawaii.  Sure enough, the accomplishment is documented in the Field Day results in QST for December 1955, where the grainy photo of his station, the miniature transmitter and an ARC-5 receiver, are shown.

Seventy years ago, the March 1956 issue of Radio Electronics showed this idea, sent in to the magazine by one Jess Jacobson, of how to turn a 5-tube radio into a metronome for the aspiring musician. A few components, including a neon lamp, are simply added to the radio to form a relaxation oscillator from the final audio stage. An RC circuit charges up until it is able to light the neon lamp, at which point a click is heard in the speaker of the radio, which has been tuned to a blank spot on the dial.

Seventy years ago, the March 1956 issue of QST featured this two-transistor transmitter for 40 meters. The author, Laird Campbell, W1CUT, noted that the QRP rig probably wasn’t going to get a top score in any contest. It was strictly for experimenters who wanted to get up to speed on the new transistors that had recently become available. He also noted that this was probably the first time ever that QST had shown pictures of a transmitter full size!

The circuit used to CK761 transistors, running on 8 penlight batteries. Since different parts of the circuit required different voltages, multiple taps were used. Campbell reported that the set had worked many contact over the prior months, including 8 states worked. The best DX was 800 miles. All of this was accomplished by simply calling CQ, without any prearranged schedules, which he deemed unsporting. He did not the problem, though. Another station hearing his call might assume that the path was simply not there, even though the QRO signal would get through just fine. He dismissed calling “CQ QRP,” as this would be interpreted as wanting to make contact with other QRP stations. He proposed something that never caught on, namely, calling CQ TR to let the other guy know that the weak signal was the result of a transistorized QRP rig.

Seventy-five years ago, the cover of the March 1951 issue of Radio Electronics featured Robert Gunderson, W2JIO,  in his radio lob, sound studio and ham shack at the New York Institute for
the Education of the Blind.  We’ve previously seen Gunderson as the mentor, in 1941, of deaf-blind ham Leo Sadowsky, W2OFU.  But Gunderson was a remarkable figure in his own right.  He started at the Institute as a student in 1928.  Upon graduation in 1937, he was put to work heading the school’s radio vocational department.  You can see a complete biography at this link.  You can also find a good look at his work in the March 1951 issue of QST.

The magazine included an article by Gunderson regarding adaptation of test equipment for the blind.  But as the cover hints, it wasn’t just a matter of accessibility for the blind.  Gunderson made the instruments better for sighted individuals as well.  Most of his adaptations involved audible signals, showing when a Wheatstone bridge was in balance, or when two signals were zero beated.  Since these phenomena involved extremely precise measurements, they were beneficial to all servicemen.  And since the feedback was audible, even a sighted repairman benefited, since he could keep his eyes on the work while making the measurement.

One hundred years ago this month, the March 1926 issue of Popular Mechanics showed how to build this crystal set, which the magazine said could be put together for just fifty cents. A unique feature was the tuning. The coil, wound honeycomb style, was rotated through two tin plates. According to the magazine, the set would provide good volume on local stations.