Fifty years ago this month, the April 1971 issue of 73 Magazine was a special issue devoted to FM repeaters. The cover shows Murry Sessions, the daughter of Managing Editor Ken Sessions, K6MVH, at the mike of a Drake TR-22, a one-watt portable 2 meter FM rig with six crystal-controlled channels. According to a review in the magazine, the set retailed for $199.95.

Of particular interest is the nationwide repeater directory, which took up seven pages in the magazine. The 30 kHz channel spacing had been widely adopted, with some channels designated for wideband and others for narrowband. However, there was no uniformity as to repeater inputs and outputs. 146.34 MHz was a very common repeater input, and 146.94 was a common output, but they weren’t necessarily paired. For example, many repeaters were 146.34 input and 146.76 or 146.88 output. In many cases, frequencies were shared in the same area, with different audible burst tones at the start of the transmission.

This makes sense, since crystals were expensive, and using the same frequency for two repeaters would have allowed users to save having to buy an additional crystal. When I got on 2 meters in the mid-1970s, the most common repeater pair was 146.34/146.94 (although this was not used in the Minneapolis-St. Paul area). However, 146.94 was the most widely used simplex channel. My first two meter rig had crystals for .34/.94, but also had a transmit crystal for .94.

In the 1971 listing, Minneapolis had a repeater with an output of 146.46. The “priority input” was 146.34, with a “courtesy input” of 146.94. The magazine noted that this system was in operation 24 hours. Many systems had limited operational hours. The Minneapolis system also had an input on 6 meters, 53.64 MHz.

Two meter FM saw great growth in the following years, fueled partly by the availability of autopatches to allow phone calls to be made from a mobile or portable radio.  This continued through the 1970s and 1980s, but waned considerably with the rise of the cell phone.  My first two meter radio was a semi-homebrew portable unit with four channels.  Around 1976 or so, I bought a Drake TR-22C, the twelve-channel updated version of the one shown above.  It was loaded with crystals for popular repeater pairs, which had by then been standardized.  Therefore, almost anywhere I travelled with the radio, I was probably within range of a repeater, and it was almost always possible to raise a fellow ham.

Fifty years ago this month, this young comrade was able to help feed his family by locating a school of fish. He managed this by seeking out the perfect water temperature, thanks to an electronic thermometer he constructed himself.

The plans for the project were contained in the April 1971 issue of Юный техник (Young Technician) magazine, which also contained the plans for making the raft, shown at left. It included a number of other circuits, including the one transistor regenerative radio receiver shown below.

It’s likely that the readership of Radio News a hundred years ago was mostly young men who had been bitten by the radio bug.  The April 1921 issue carried this article entreating them to get their friends interested in the hobby. It pointed out that there were “many bright boys and young men who are spending their evenings in idleness or bad company simply because they haven’t found an interesting hobby.” The ideal hobby, of course, was amateur radio, and it was one that would lead to a big future for those who got in on the ground floor with a thorough practical knowledge of radio.

But there was more: “boys, there is an additional reason for getting interested in radio. The ‘reason’ being shown in the accompanying photographs. Some of you fellows may not have known it, but many of the fair sex have gone in for radio and more are taking it up all the time.”

That’s right. Amateur Radio was a veritable chick magnet!  “What could be more interesting than a radiofone conversation during a long, lonesome evening with a sweet-voiced girl on the other end?  Wait until the radiofone becomes more universal and we predict many a romance will be started just this very way.”

The promised photos include, at the lower left, an unidentified girl at her radio set, somewhere in Brooklyn. And at the lower right, a “girl amateur” is receiving some C.W. instruction at the Second District Radio Convention Exhibition.

The picture at the top of the page isn’t, it turns out, just a candid shot of two young women tuning in their crystal set while out for a walk. It’s actually a still from the silent film short feature “Eve’s Wireless“.

The article identifies the actresses as Peggy Brady and Alice Brady of the Ziegfeld Midnight Frolic, a somewhat risque rooftop after-hours presentation after the Ziegfeld Follies let out for the night.

You can view the entire film here:

Sixty years ago, this gentleman, probably Gordon Carlson of the DeVry Technical Institute of Chicago, made the cover of the April 1961 issue of Radio Electronics magazine by mowing his lawn automatically with this fully automatic electronic lawnmower. But this wasn’t a pie-in-the-sky idea concocted by a futurist. Mr. Carlson actually built the thing, and described the electronics in detail in the magazine. Since the mechanical details would vary from lawnmower to lawnmower, he left many of them to the reader. In this case, the automation was added to a Jacobsen Lawn King. But the basic idea was rather simple.

Buried a few inches under the lawn was an insulated wire carrying an alternating current. On front of the mower (shown in the inset in the lower right hand corner of the cover) were two pickup coils, one to the left, and one to the right. When the mower was directly above the wire, the induced currents would be equal, and the mower would proceed straight ahead. But if one current got stronger than the other, the signals would be amplified by the electronic circuit and would trigger a relay which would steer the mower to either the left or the right, using an electric motor coupled to the mower’s steering. To keep the machine from constantly hunting, a further refinement was added. If the mower was only slightly off course, the corrections would be made slowly. But if it got way off track, the steering motor would operate at high speed.

As a nod to safety, a limit switch in front of the mower would cause it to stop if it encountered an obstruction such as a toy, a pet, or a child. As shown in the likely staged photo below, this scheme could apparently be trusted.  I scoured news archives and found no reports of a young woman meeting her demise in a lawnmower accident in that time frame.

No, this device wouldn’t pick up music from the United States Marine Corps, but it would allow your car radio to listen in on the local maritime radio traffic on the 2-3 MHz marine band.

The project appeared in the April 1961 issue of Electronics Illustrated. It used a single 2N140 transistor as an oscillator on 3.5 MHz, when mixed with the 2-3 MHz signals, the output could be heard on the broadcast band. It was powered by a battery which was said to be good for hundreds of hours with the low current drain circuit.

The cost was said to be about $10, which would quickly be paid back with fresh fish. The idea was that by monitoring the traffic from commercial fisherman, the hot fishing spots would be revealed.

At first glance, this radio kit sounds like a great deal. For only $2.95, including postage, it looks like you get a kit to put together an “All American Five” radio, for considerably less than what it would cost to purchase one already assembled.

When I saw it, I was a little bit dubious, so I read more closely. Sure enough, it looks like it includes all of the components. I was still suspicious, so I looked even more closely, to make sure that it was a real five-tube superhet, and not some kind of stripped down crystal set. But sure enough, it includes a calibrated tuning knob and a volume control knob. Yep, it sounds like the real deal, and it sounds like, as the ad announces, a good way to get started in radio.

I bet there were a few who came to the same conclusion and sent in their $2.95. But first, let’s read it one more time, very carefully this time.

For $2.95, you don’t get started in radio. You get started on this radio, but you don’t finish for that price.  They don’t furnish all of the components.  They furnish all but the components!  You get the cabinet, the chassis, name plate, the knobs (but apparently not the volume control or tuning capacitor), the back panel, and five tube sockets (but no tubes).  In their generosity, they even include four screws and three grommets.  But that’s it.  For the actual components, you’re on your own.

The ad appeared 70 years ago this month in the April 1951 issue of Radio-Electronics.  It was offered by the Lormel Products Co. of 10406 Superior Avenue, Cleveland, Ohio.  They don’t seem to be in business any more.

Sixty years ago, the April, May, and June 1961 issues of the British journal Practical Wireless contained the blueprints and construction details for this ambitious project, dubbed the “Roadfarer.” The set was a completely self-contained portable that would tune the longwave, mediumwave, and FM broadcast bands. It would operate on batteries, but also included an AC power supply to give greater economy when close to the mains.

The magazine promised that the set would be found simple to build, thanks in large part to the use of printed circuit boards. A total of three boards were used, for the AM tuner, FM tuner, and audio amplifier.

The magazine announced prizes for the best constructional work carried out by readers. A panel of judges had been assembled from representatives of the firms whose parts were used in the receiver. Some of those firms kitted all of the parts needed to construct the set, and those were found in subsequent issues of the magazine.

Despite the announcement of the prizes, I wasn’t able to find any listing of winners in subsequent issues of the magazine.