One tube radios don’t get much simpler than the one shown here, which appeared in the November 1944 issue of Radio Craft magazine, having been sent in by one Reggie Baker of Miami, Arizona. The circuit was described as a split Hartley with a type 30 tube. It could operate with two dry cell batteries.

Another Hartley oscillator was used in the circuit shown below, a phono oscillator. This circuit used a 6A8 or 12A8 pentagrid converter tube.  It had been sent in to the magazine by Ralph Day of Moncton, N.B., who pointed out that it could also be used as a signal generator, using either phonograph music or an audio oscillator.  It would appear that this is the same person as the Ralph Granville Day named in this 1959 marriage certificate, as the groom’s occupation is described as “T.V. and Radio.” He was born in 1924, which would have made him 20 years old at the time of the magazine submission. He died in California in 2003, and his obituary notes that he served during the war in the Canadian Merchant Navy, and after the war spent several years at sea as a radio operator.