New Circuits

Though radio had changed rapidly and radically over the past decade, that change only accelerated in the early twenties.  New regulations, the broadcast boom, the abandonment of spark for CW, and new transmitter, receiver, and antenna designs were all happening simultaneously.  No single one drove the others, but all together they advanced the radio art in a self-supporting feedback loop. Since publication of John Reinartz’s (1QP or “1-Kewpie”) tuner1 in 1921, hundreds of hams had used it on CW with … Continue reading

The Audion

Vacuum tubes revolutionized radio, changing it more than any other single invention. When first introduced, however, even the scientists and engineers working with them did not fully understand how they worked. One of the first tubes to appear in QST was the Audion, by DeForest. Although it had been introduced back in 1905, it was expensive and amateurs did not begin to use it until seven years later, when 22-year-old Edwin Armstrong demonstrated its practical use as a regenerative detector. … Continue reading