Stromberg Carlson Model 350R Half-Round Console Radio (1939)
The Stromberg Carlson 350R is an impressive three-band 11-tube console radio that features a tuned RF stage, three-
way high-fidelity control, Automatic-Frequency-Control (AFC), concentric coarse/fine tuning control, magic-eye tuning
indicator and push-pull output stage with the "acoustic labyrinth speaker" system. Tuning ranges are 530 - 1700kc, 1700
- 5600kc and 5600 - 18,000kc. The tube line-up is 6K7 (RF amp), 6A8 (mixer), 6F8G (LO and LO freq control), 6K7 (IF),
6H6 (discriminator/demodulator/avc), 6B8 (discriminator/1st af), 6C5 (phase invertor), 6F6 * 2 (push-pull output), 6U5
(tuning indicator) & 5Z3 (rectifier). Interestingly, the RF stage is only used with the standard broadcast manual tuning
range. The high-fidelity control, like that on a number of other contemporary receivers, is achieved, in part, by adjusting
the bandwidth of one of the IF filters. The knobs are, from left to right, voulme, fidelity control high/normal-tone, tuning,
waveband selection, on/off/bass. The schematic may be found here, courtesy of NostalgiaAir.
The AFC serves to lock-in the frequency of the LO to that of a received broadcast carrier, mitigating the effects of drift
caused by component aging, temperature changes, and so forth. This was especially important when using the electric
tuning feature (i.e push-button tuning). An AFC defeat switch is located on the rear of the chassis, mainly for usage of the
service technician when aligning the set. Philco employed the same technique on a number of their higher end sets, such
as the 37-116. They referred to it as "magnetic tuning".
This radio was a birthday present from my wife and was purchased in original condition from Bernie Samek at Old Country
Barn Antiques in Brimfield, Mass. I have since fully restored it and it occupies a prime spot in our dining room.