Monthly Archives: May 2019

1934 Two Tube Regenerative Shortwave Receiver

1934MaySWcraft

This handsome little two-tube shortwave receiver is described in the May 1934 issue of Short Wave Craft magazine. The circuit was designed by the National Radio Distributing Co., which presumably had all of the parts for sale, and used two type 30 tubes. A 45-volt B battery was sufficient for normal reception, but to pull in the weak signals, it was recommended to use 90 volts for the amplifier stage. In addition to the tuning dial, two other controls were visible on the front panel. One was a variable capacitor for adjusting regeneration, and the other was a rheostat for setting the filament voltage.

A well-insulated antenna of 45-100 feet was recommended.

1934MaySWcraftSchematic



Eico 720 Transmitter, 1959

1959MayEISixty years ago this month, the May 1959 issue of Electronics Illustrated carried a review for the then-new Eico 720 transmitter.

The reviewer noted that the kit could be assembled in a week of evenings, and was within the capabilities of the beginning kit builder. The set had a maximum input power of 90 watts, but the plate current meter had a red line indicating the 75 watt limit for novices, the kit’s primary market. The review noted that the transmitter ran cool, despite its compact size. The output filtering was especially lauded, as the transmitter was well protected against television interference.

The kit sold for $79.95, with the wired version selling for $119.95. The review concluded by declaring the 720 a Good Buy for either the novice or the veteran ham.

For a look at a remarkably well preserved specimen, see this link.



Dr. W. Eberle Thompson: Abolitionist, Underground Railroad Conductor, Doctor, Radio Fan

1939MayRuralRadioShown here is Dr. William Eberle Thompson of Bethel, Ohio. The 104-year-old doctor is wearing headphones and listening to WLW radio. The photo was taken on the occasion of an interview by Ed Mason, WLW Farm Events Announcer, who wrote about the interview in the May 1939 issue of Rural Radio magazine. Mason noted that he “interviews some mighty interesting and important people. But never have I talked to anyone who could match this country doctor who voted twice for Lincoln.”

While the magazine article is lacking in details, the centenarian doctor is almost certainly the same person described in the book The Underground Railroad: An Encyclopedia of People, Places, and Operations. In addition to merely voting for Lincoln, Dr. Thompson played a much greater role in ending slavery. “In his youth, the family’s two-story brick residence at 133 South Main Street was a safehouse. In adulthood, his home and office at 213 East Plane Street received refugees.” The Rural Radio article mentions that Dr. Thompson’s “hands and eyes, now weary from service to his neighbors, had brought him fame as a crack shot with his old muzzle-loading rifle.” The old muzzle loader had been put to good use, since “to secure slaves in flight from posses, Thompson shot their bloodhounds.”

According to this site, Dr. Thompson became an active member of the Bethel Underground Railroad network as a teen. He guided fugitives from Bethel to the Elklick area near Williamsburg. He practiced medicine in the community for eight decades and was active in village government and social affairs.

The headphones in the photo were a gift, as explained in the magazine article:

Long after the switch had been turned which took us off the air, we talked. I learned that he liked to listen to the radio, and especially news broadcasts, but his hearing had failed and he had not used his radio for several years.

When Phil Underwood, WLW engineer, heard this, he opened that magic box that a radio engineer always carries. He brought out headphones, special amplifiers, wires and switches. When we left, Dr. Thompson was sitting by his radio hearing distinctly for the first time in years hearing news by the magic of radio.

The Rural Radio article refers to the doctor as  “C.  Eberle Thompson.”  This is almost certainly an error, since it’s unlikely that there was another centenarian doctor in the same small town.    Dr. Thompson died in 1940, a few months shy of his 105th birthday.  He continued to practice medicine until about a month before his death.