First auto radios

[july76]

  Automotive history with the technological develpment is a really interesting area to me. Recently I've been
  reading about the auto radio and his early steps. I haven't found nothing about that matter in Cadillac.
  If i'm right that was firstly offered as an option in the 1930 model ¿? I suppose that it was a Philco with
  controls in the steering column. But when it was first installed as a factory accesory? And when as a
  in-dash installation?

[bcroe]

The first was a variation on the dry battery powered radios such as used on a farm
with no AC; A battery, B battery, directly heated filament tubes.  I think next they
used indirectly heated filament (6.3V) tubes with a dynamotor to supply high voltage
DC.  The vibrator soon displaced the dynamotor.  Instead of a rectifier tube, a
syncronous vibrator was tried; that displaced by the 0Z4 rectifier.  Next big change
was to 12V.  Building on that, some tubes were developed that could run directly off
12V, with an early transistor output stage.  About 63 we got all transistor, and FM. 
Then stereo. 

Bruce Roe

[Doug Houston]

Auto radio as such dates back to about 1928. Previously, people put battery home sets in the back eat, and jury-rigged antennae on the car. That doesn't count as a TRUE auto set.

The Galvin brothers in Chicago come the closest to being the first with a truly installed, and remotely controlled auto set. They made a motor car radio, and in keeping with the convention of naming music- reproducing devices, named their product: MOTOR OLA.

Cadillac's first radio was offered for the 30-31 models, and was designed by Delco-Remy. Manufacture has been traced to GM Radio Corp; a joint venture of GM and RCA, which was very short-lived. The anti-trust legal action in the courts made RCA pull out. That's  another long tale.

he radio used tubes with 2.5 volt filaments, and a bank of dry cells in a floor pan box for the high voltage (HV).  Both dynamotors and vibrator power supplies for HV were yet in the offing. Joe Scott (Houston TX) has one in his 1930 V16 roadster. Because of the strange design, Joe and I had to re-design the audio section of his set over the phone. 

Cadillac was able to contract with Wells-Gardner, of Chicago for their custom sets from 1932 through 1939, with RCA supplying one of the 38 model sets, adapted from a '38 Buick model. The radio service manual for Cadillac starts at 1932, and runs through 1940. I have one.

So, that's my answer. There's probably moore to it, but that should be a little help.