HOME ENTERTAINMENT -  MODEL 20 (Junior and Junior Combo) RADIO

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Type:  8 tube TRF set
Circa:  July 1930
Tube Lineup : 1 x UX80;  5 x UY227 ;  2 x UX245
Power Input :  115 VAC - 25 or 60 Hz
Cabinet:: Console
Comment:  The radio itself is called the Junior. When provided with a record player, it was called a Junior Combo. A model 20 Junior Combination was more expensive than the model 20 Junior, because the cabinet was larger ,and it had a record player in the top.

Link for Model 20 schematic
Link for Model 20 power unit
The model 20 used a Tesla motor in the phonograph. It is briefly described in this document. .

Model 20 Junior front view

Model 20 Junior closeup of tuning eustachian. Knobs are missing.

Model 20 Junior rear view

Model 20 Junior closeup of chassis

Model 20 Junior power supply closeup

Model 20 Junior Combo.  The motor in the Junior Combo phonograph has an adjustable centrifugal speed governor in it,. Not only that, the speed can be adjusted for different records, The motor can run on 25, 50, and 60 cycle AC mains. Conventional motors have to have different armatures to run on the different mains frequencies.

Model 20 Junior Combo nameplate decal.

Model 20 Junior Combo phono motor as mounted in the radio.

All photos in this table via Kijiji.ca

The Tesla motor shown here is not the same model as fitted in the Junior Combo radio although the frames are identical, and the principle of operation  are the same..Lewis Bodkin had three of these motors at one time. They were marked  " 25 to 30 CPS" ,  "50 to 60 CPS" and one said "60 cycles" only.  Mechanically and electrically speaking, all three motors were identical. The speed of this motor is determined by a centrifugal governor with a disk  bake.Since there are no magnetic poles in the armature created by electrical coils, wires, gaps in the steel, or permanent magnets, the  field coils are free to create their own pathways in the disk armature.

Closeup view of the governor which controls the speed of the motor,

Model 20 phono motor closeups and nameplate.  Note that this motor is capable of operating over a 5 cycle per second frequency range.  Type 2 25 to 30 cps 105 to 120 VAC.

All Model 20 photos in this table by Lewis Bodkin.

	This ad for the Model 20 Junior Combo appeared in the December 1930 issue of the Radio Sales periodical. Click on image to enlarge. (Provided by Lewis Bodlin)
	This announcement for the Model 20 Junior Combo appeared in the January 1931 issue of the Radio Sales periodical. Click on image to enlarge. (Provided by Lewis Bodkin)

This ad for the model 20 Junior appeared in the Fall 1930 and  Spring 1931 editions of the Eaton's Winnipeg catalogue. (Provided by Lewis Bodkin)

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Credits and References:

1) Canadian Marconi Service Manual Vol. 1
2) The Early Development of Radio in Canada 1901 to 1930 by Robert Murray
3) Lewis Bodkin  <05bodkin555(at)gmail.com>
 
 

Jun 2921