Eighty years ago this month, RCA’s newsletter for hams, RCA Ham Tips, November 1939, carried this two-tube transmitter for 40 and 20 meters. The circuit was submitted to the magazine by Cuban Adolfo Dominguez, Jr., CM2AD, who earned himself a new 809 tube and $5. It used a 6L6-G (an RCA 6L6-G, to be specific) oscillator which drove an 809 final. CM2AD reported that he had built three such rigs for friends, and they all worked well. In fact, he had used the rig himself for Worked All Continents and Worked All States, with 62 countries worked.

The set used 40 meter crystals for both bands. Having first been licensed in the 1970s, to me, Cuban CW signals are synonymous with chirp. That was apparently the case in 1939, as the editors diplomatically raised the subject: “Although CM2AD did not mention trouble from ‘chirps’ when the 6L6-G is keyed, it is possible that a steadier note can be obtained” by making a slight modification to the circuit.

CM2AD had the same circuit published in QST in the May, 1939, issue.