This radio was acquired in a garage sale,
where still several hundreds of sets were left, after
collectors had picked out the most popular items.
It is in a fair condition. Only the dial glass is
The model identification on the back side of
the chassis suggests that it is model 533. However, the
radio employs 5 tubes plus a ballast resistor. Therefore
the model number for this radio should start with a
"6". Closer inspection with a magnifying glass
reveals that the first digit indeed is a "6".
There is still a mystery to be solved !
According to the schematic in Rider's Manual (page 8-8), model
633 is using the following tubes: 6A7, 6D6, 6Q7G, 25B5, 25Z5 and
ballast resistor M-49-B.
My radio, however, does not show up the 25B5 (a direct coupled
power amplifier) as output tube, but the beam power amplifier
25L6, which also has a different base than the 25B5. The socket
in the chassis has an original imprint "25L6" and there
are no signs that the base has been replaced outside the factory.
Is somebody aware of an official modification as described here
As the radio did not have visual damages, I cleaned out the
interior of the cabinet and applied 110 volts (in small steps).
Thereafter on both bands many stations could be heard.