Seventy years ago this month, the February 1947 issue of Radio News carried the plans for this handie talkie for two meters.
The author was C.T. Haist, Jr., W6TWL, and this was the his third version of the set, with earlier ones appearing in the June 1944 and April 1946 issues of QST. Those earlier versions had one bug that still needed to be worked out: Since they used the same oscillator tube for both the transmitter and receiver, the result was that the transmit and receive frequencies were slightly offset. This didn’t pose a problem when working a fixed station, since the other station would probably be using a separate transmitter and receiver. But when two portable sets were used, the result was that each station would need to retune after each transmission, resulting in the two stations chasing one another around the band.
This set solved the problem by using separate tubes for transmit and receive, with a third tube used in common in both circuits. Transmit-Receive switching was accomplished with a three pole double throw switch.
The compact set had room for a 67-1/2 volt B battery and 2 flashlight batteries running the filaments. The built-in antenna was a repurposed telescoping automobile antenna. The set drew about 15 mA on transmit, meaning that the total input power was about one watt. At 8-10 miles line of sight, the set gave good signal reports. With batteries, it weighed in at about three pounds, and measured 2-1/4 x 2-3/4 x 9-1/4″