Firestone-Stewart-Warner Model R1332 5-Tube Auto Radio
Radio Service Data Sheet
March 1936 Radio-Craft

March 1936 Radio-Craft [Table of Contents] Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Craft, published 1929 - 1953. All copyrights are hereby acknowledged.

This Radio Service Data Sheet for the Firestone-Stewart-Warner Model R−1332 automobile radio schematic appeared in the March 1936 issue of Radio−Craft magazine. I could not find any images of the R−1332 version, but evidently the equivalent was the Stewart-Warner Model R−133, for which I did manage to locate a photo. Back in the day, installing a radio in your car or truck was no simple matter. It came as as least three separate components - the receiver, which mounted under a seat or in the trunk, a tuner which mounted in or under the dashboard, and an antenna that often times consisted of a wire loop strung under the auto chassis, forming a loop. Some auto radio models had the power supply in a separate chassis, which also mounted under a seat or in the trunk.

Firestone-Stewart-Warner Model R1332 5-Tube Auto Radio Radio Service Data Sheet

(Power supply protective resistor; calibrated dial; tone control.)

The chart at the left shows the locations of the tubes and their voltages, as measured to chassis. The usual high-resistance meter must be used. The bias on V4, of -23 V., is measured from chassis to the ungrounded filter choke terminal.

With the volume control set at maximum, attach the service oscillator between V1 grid cap and chassis, and adjust all I.F. trimmers for best signal. R.F. alignment is made at 1,400 kc., the adjustment being made on the trimmer located nearest the shaft end of the gang condenser.

The dial calibration may be corrected by tuning to a station of known frequency around the center of the dial and, while holding the knob so that it cannot turn, set the pointer to the correct position. The screw that controls the pointer is at the rear of the control head, and may be turned by an ordinary small screwdriver.

The special "globar" protective resistor across the secondary of the power transformer cannot be tested with an ordinary ohmmeter since it will have a resistance of several megohms when cold.