October 1937 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.
Installing radios in cars and trucks was big business
in the 1930s. Most cars of the day did not include a radio as standard equipment. In fact,
the most challenging aspect of installing a radio in an automobile was the antenna and tuning
mechanism. Electronics magazines of the era - Radio-Craft, Short Wave Craft, et al - had photos
of technicians with equipment spread all over the public sidewalks next to where the car having
the radio installed is parked. Yep, the car radio installers came to your location like the guys who
replace windshields. This photo of the Crosley Model A-157 Fiver Roamio auto radio was found
on he RadioMuseum.org
5-Tube Superheterodyne; Automatic Volume Control; Direct Tuning
The Fiver Roamio direct-tuning, auto-radio superheterodyne.
The power supply and speaker are self-contained, the latter being mounted on the left side
of the housing.
The Crosley Model A-157 auto-radio set is a single unit, 5-tube super-heterodyne receiver.
incorporating A.V.C. and many advanced features in circuit design. The power supply unit is
an integral part of the receiver chassis and uses a primary-type vibrator.
Tubes and Voltage Limits. The following table gives the functions.. of
the tubes used, together with the, voltage readings between the tube socket contacts and the
receiver chassis. Voltage readings taken with a 1,000 ohms/volt, 500-V, voltmeter (except
filaments) with receiver in operating condition and no signal input.
Connect the output meter to 3 and 4 of the 6K6G output tube socket. Be sure the meter is
protected from D.C. by connecting a condenser (0.1-mf. or larger - not electrolytic) in series
with one of the leads.
1.Tuning I.F. Amplifier to 455 kc
(a) Connect the output of the signal generator through a 0.02-mf. or larger. condenser
to the top cap of the 6A8G Osc.-Mod. tube, leaving the tube's control-grid clip in place.
Connect the ground lead from the signal generator to the receiver chassis frame. Keep the
generator leads ' as far as possible from the control-arid: leads of the other screen-grid
Posted August 24, 2017