This radio has a bakelite cabinet and
employs following tubes: 12SA7, 12K7GT, 12SQ7, 50L6GT and 35Z5.
In the rear part of the cabinet a loop antenne is providing
antenna signal to the radio.
I bought this radio at the annual
"Rock around the Jukebox" happening in the
"Autotron" in Rosmalen in The Netherlands.
Judging from information in Rider's manual
(Volume 11- page 22) the chassis is a DL type and the model
number is 330. IF frequency is 455 kHz and one band is covering
The schematic and parts list are shown in Beitman's "Manual of 1941
Most Popular Service Diagrams" (thanks Antonio from Portugal),
which reveals the likely year of origin of this radio.
The primary coil of the first IF
transformer appeared to be interrupted. The DC resistance was
about 2 kohm instead of the 30 to 50 ohm which I measured on the
other ones. A coil from the junk box with an inductivity of
several mH was converted into a coil of 1.84 mH by removing the
necessary amount of windings and placed on the position of the
The coil at
the lef is original. At the right hand side of the coil core the
replacing coil can be seen.
Most paper capacitors had too much leak.
The interior of these capacitors was removed and replaced by high
quality capacitors of the proper value. Thereafter the paper
tubes were closed with a kneadable two-component epoxy. The same
procedure was followed for the electrolytic capacitor.
All parts on top of the chassis (IF cans,
speaker and tuning capacitor) were removed and cleaned and the
chassis itself was cleaned as well. The bakelite housing and the
two knobs were cleaned and polished with a car cleaner
(product available in car shops in The Netherlands: Commandant 4).
The IF transformers were peaked on a
signal of 455 kHz from a signal generator. Hereafter the radio
played again and showed up a very good sensitivity. An external
antenna is even not really necessary.
Unfortunately the back panel was missing.
A collector was so kind as to send me a picture, so I will be able
to reconstruct it.