Anyone else remeember the 0XZ4 rectifier? Common is such car radios.
And noisy (in the RF sense) as the dickens. Ran very hot, too. It had
a half-wave cousin, the OY3 (IIRC).
B-supplies for auto radios seemed to come in a couple of flavors--gas
cold-cathode rectifier, traditional hot-cathode rectifier, and
synchronous vibrator rectifier--as well as an occasional plug-in
semiconductor replacement for the miserable OZ4. I don't recall
seeing a selenium rectifier in such rigs, however.
The radio in my Nash Metropolitan uses a vibrator rectifier. It was a
lost cause and when I rebuilt it I replaced the rectifier with a solid
state replacement.
On the subject of tube radios, I picked up an RCA Victor BP-10 awhile
back; this is a portable from about 1940 and it's actually pretty darn
tiny for a tube-based unit. (And it runs off a 63.5V B battery (#467)
and one D-sized 1.5V battery. Amazingly you can still buy the 63.5V
batteries new...). Anyway, I bring it up because aside from its small
form factor it has one other attribute I've never seen in a tube radio
-- it starts playing almost immediately (within a second) of turning it
on and the tubes never seem to get warm at all. All the other tube
units I've ever seen take 10-20 seconds to warm up first. Makes me
wonder a) what's special about this unit and b) why other units didn't
do the same -- seems like a pretty useful feature.
Any ideas?
Josh
Most all the the portable radios of this time used thin directheated filaments.Most table
models used a secondary cathode because the filamentswere strung together in series to run
directly off the mains. Thiseliminated the need for a transformer.Most of the tube radios
could also be run from the AC line.The filament voltage was created by a wasteful
resistoror ballast tube. Neither was optimal as it required thatthe filament be supplied
with rectified and filtered DC.The Selenium rectifiers of the day will be sure to fail
withuse. They need to be replaced with silicon diodes andin some cases a limiting
resistor.In any case, the direct filament heats almost instantly.The indirect cathode
requires more time to come up to temperature.The portable radio uses less output power as
well usuallyusing a 3V4 output tube.Dwight
