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General Electric (GE) Model J-72 Cathedral Radio (1932)
The General-Electric model J-72 radio was introduced in
December of 1932, priced at $47.50 complete with tubes. It
was manufactured for G-E by RCA under an agreement
between the companies made earlier that year - see my
Westinghouse WR-30 page for more details. As a result, the
chassis was also used by RCA (for example, see model
R-70).
G-E advertised this radio as "a 7 tube early English type
compact with cathedral window type design. Super-het-
erodyne, full volume, new type tubes, pentode output,
full-size dynamic speaker, and all other new General
Electric features. An unusual radio at an unusually low
sale price".
The radio covers the American standard broadcast band
from 525 - 1550kc and uses an ac-powered 7 tube super-
heterodyne chassis. The tube line-up is:- 58 (RF amp), 58
(mixer), 56 (LO), 58 (IF amp), 56 (detector), 47 (power amp),
80 (rectifier).
Compared with its bigger brother the 8-tube J-82, this model
provides no Automatic-Volume-Control (AVC), since it omits
the single-tube AVC stage. Furthermore, it has an unusual
arrangement for manual adjustment of volume in that the
control knob varies the negative bias applied to the type 58
variable-mu pentodes in the rf, mixer and IF stages. The
schematic can be found at the Nostalgia Air site under the
RCA model R-70.
The chassis view of the J-72 to the right shows the tube
shields and loudspeaker frame painted in red. This is an
entirely original feature done for its showroom "wow" effect.
I have restored this radio both cosmetically and electrically.
The chassis is deep and cramped, rendering access to a
number of the old capacitors and resistors difficult. Further-
more, it originally used a lot of wiring covered with rubber
insulation that had become brittle. All this had to be replaced.
The filter-condensers are housed in a heavy gauge steel
can, affixed to the chassis using lugs, accessible beneath the
chassis but concealed below the mixer/LO coil assembly. This
housing can be seen at the front right of the chassis (viewed
from the rear) in the photo to the right. The coils had to be
removed and the lugs cut off using a Dremel tool in order to
release the unit. Once removed, I dug out the tar and embed-
ded components with the aid of a heat gun and replaced
them with modern equivalents. The completed capacitor pack
and lugs were then re-attached to the chassis using
cement.
December of 1932, priced at $47.50 complete with tubes. It
was manufactured for G-E by RCA under an agreement
between the companies made earlier that year - see my
Westinghouse WR-30 page for more details. As a result, the
chassis was also used by RCA (for example, see model
R-70).
G-E advertised this radio as "a 7 tube early English type
compact with cathedral window type design. Super-het-
erodyne, full volume, new type tubes, pentode output,
full-size dynamic speaker, and all other new General
Electric features. An unusual radio at an unusually low
sale price".
The radio covers the American standard broadcast band
from 525 - 1550kc and uses an ac-powered 7 tube super-
heterodyne chassis. The tube line-up is:- 58 (RF amp), 58
(mixer), 56 (LO), 58 (IF amp), 56 (detector), 47 (power amp),
80 (rectifier).
Compared with its bigger brother the 8-tube J-82, this model
provides no Automatic-Volume-Control (AVC), since it omits
the single-tube AVC stage. Furthermore, it has an unusual
arrangement for manual adjustment of volume in that the
control knob varies the negative bias applied to the type 58
variable-mu pentodes in the rf, mixer and IF stages. The
schematic can be found at the Nostalgia Air site under the
RCA model R-70.
The chassis view of the J-72 to the right shows the tube
shields and loudspeaker frame painted in red. This is an
entirely original feature done for its showroom "wow" effect.
I have restored this radio both cosmetically and electrically.
The chassis is deep and cramped, rendering access to a
number of the old capacitors and resistors difficult. Further-
more, it originally used a lot of wiring covered with rubber
insulation that had become brittle. All this had to be replaced.
The filter-condensers are housed in a heavy gauge steel
can, affixed to the chassis using lugs, accessible beneath the
chassis but concealed below the mixer/LO coil assembly. This
housing can be seen at the front right of the chassis (viewed
from the rear) in the photo to the right. The coils had to be
removed and the lugs cut off using a Dremel tool in order to
release the unit. Once removed, I dug out the tar and embed-
ded components with the aid of a heat gun and replaced
them with modern equivalents. The completed capacitor pack
and lugs were then re-attached to the chassis using
cement.
..early English type compact with cathedral window design.
Believe your own ears!
Copyright TubeRadioLand.com
Dec 1932, Radio Retailing
pg 25
pg 25
Dec 21st 1932,
Syracuse NY
Syracuse NY
Dec 1st 1932,
Galveston Tx
Galveston Tx