<VV>Transistor Radios

[Tony Underwood]

At 08:05 hours 05/12/2006, Padgett wrote:
>Delco radios actually went through several transitions in the 50s and 60s
>1) high B+ voltage tube type radios with vibrators (pre-1957)
>2) low voltage (12v B+) radios - 1957-1959ish (not at home so cannot 
>look up)

Actually, Delco built radios with space charge tubes through 
1962.   All space charge tube radios (that I've seen used in GM 
vehicles) used a Germanium output transistor, including those which 
started in the later 1950s.   As I recall, the '58 Chevy wagon we had 
also had a space charge radio with a Germanium transistor output on a 
heat sink in the back.    The '56 Buick before it had a vibrator 
radio.    You could hear it hum when you turned it on as it was warming up.

>3) low voltage tubes with a single transistor output (1959-1962)

...you sure it wasn't '58?   ;)


>4) all transistor radios (1963 model year)


Yep.

>Keep in mind that until the late fifties, transistors were 
>considerably more expensive than tubes and used only in high-end sets.


The single Germanium transistor used as a Class-A output was a LOT 
cheaper than the alternative, which would have to have been a pair of 
large space charge tubes capable of driving a speaker through a 
transformer, not an easy task on 12 volts if the goal is a couple 
watts or more of audio output.     As inefficient as a Class-A power 
amplifier is, it remained a better alternative particularly when it 
was backed up by space charge tubes which eliminated the vibrator and 
power transformer and rectifier tube and large filter caps and 
associated circuitry.

The transistor in question (DS-501) was not actually manufactured by 
Delco and had a number of different nomenclatures across the  board, 
was practically indestructible and is still seen working up a storm 
in hybrid car radios to this day, some of which are approaching 50 
years old.     The radio in my '60 4-door remains pretty much 
untouched (except for replacement of the emitter fusistor about 8 
years ago after I foolishly ran the car with the battery unhooked and 
the radio on) and it still works well after all this time.

Who'd uh thunk...


tony..