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Dave
completed the restoration of one of the world's first
under-dash car radios in the world
The Atwater Kent Model 424 AM Radio
with self-contained speaker.
This vintage radio pre-dates the
vibrator tube and uses an "Inverter and Synchronous
Rectifier" to bump the nominal 6 Volts DC up to 150 Volts
DC for the four vacuum tubes. Restoring this old radio was quite
a challenge and the mechanical inverter worked in an analogous
way as their modern solid state counterparts. When properly
adjusted the output of the power supply is smooth and the hum is
reduced to background noise. Installation amounted to two bolts
to the bottom of the dash, and a single bolt on the sliding
bracket to the car's firewall. This radio operates on 6 Volts DC
(actually 7.25 Volts DC is better) and consumes between 2 and 4
Amps. Dave mentioned, "I had to swap out the old antenna
lead-in because it was hard-wired to the car's antenna." In
it's place we installed the standard modern antenna lead-in and
connector. We also had to change the caps and tweak the
super-heterodyne circuitry. The result is a great sounding radio
that works as good as the day it was built. Dave restored this
peice to museum quality.
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