Fifty years ago, the vacuum tube was still king, although its days were coming to an end. The September 1964 issue of Electronics Illustrated contained several construction projects, most of which relied on tubes. The Micron Electron Tube Company advertised a few dozen common tubes for 37 cents each. Other tubes were available at reasonable prices. For example, hams looking for finals for their transmitter could find an 807 for a dollar, or a 6146 for $2.45.

Some transistor gear was starting to show up, but it was pricey. E.F. Johnson advertised two transistorized CB handheld radios. The 100 milliwatt version sold for $109.50, and the 1.5 watt version commanded $129.50.

The construction projects included a CB preamplifier and calibrator for tuning 11 meters on a shortwave receiver.  This article bears the byline of prolific author Len Buckwalter, whose CB call KBA4480 is shown. (Buckwalter was also a ham, and his byline for ham related books and articles included his ham call, K1ODH.) This circuit used a single 6U8 (one of the 37 cent tubes), a dual pentode-triode, one half of which was used as the preamp, the other half being the crystal calibrator.

For hams, the magazine featured a transmitter for 80 and 40 meters, which the article claimed could be built for five dollars. It used a 6V6GT and a 5U4G rectifier, both of which were on the 37 cent list.

And, as fitting for this site, the magazine featured the one-tube AM radio shown above, which used a 6AL11 dual pentode. Half the tube was used as a regenerative detector, the other half being an audio amp which would deliver a full two watts to the speaker. According to the text, the circuit “has only one tube but in terms of performance it’s a mighty far cry from that one-tube job of 30 or more years ago,” with sensitivity and tone that will surprise you.

What’s intriguing about this project is that it’s probably one of the last times that an electronics magazine would feature an article on how to build a standard AM radio that appears to be designed for everyday use. The 1964 Radio Shack catalog included an “all American five” AM radio for only $7.95, so even the most frugal builder would probably save very little by building his own.

Len Buckwalter seems to still be around.  He is listed as a founder of publisher avionics.com of Leesburg, Virginia.  It appears that he let his ham license lapse at some point, but he appears to be currently licensed as KK4GJX, which is listed as being issued in 2012.  According to a biography, he graduated from college in 1951, which would mean that he’s now about 85 years old.

If you’re interested in building this radio, most of the parts should be readily obtainable. Antique Electronics Supply is probably the best supplier for the power transformer.  They don’t carry the tube, but it can be found on eBay.  On another post, I have links to suppliers where you can find most of the other parts.

References

Len Buckwalter at semiconductormuseum.com