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Philco Model '37-116 Codes 121 (Shadometer) and 122 (Dial Tuning)
January 1937 Radio-Craft

January 1937 Radio-Craft

January 1937 Radio Craft Cover - RF Cafe[Table of Contents]

Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Craft, published 1929 - 1953. All copyrights are hereby acknowledged.

Philco Model 37-116X Radio (tuberadioland.com) - RF Cafe

1937 was one of the years where radio receivers boasted major technology advances. American and European households had by then finely crafted wooden-cased radios as the centerpiece of their living rooms (televisions were a rarity), and decent reception was the norm if reasonable care was exercised when installing the antenna and avoiding static-generating appliances. The market was ready for and receptive to whiz-bang new features like automatic stations tuning, "Magic Eye" indicators, and high fidelity sound. This Philco model sported all those features and more. Of course electronics service shops loved the sophisticated electromechanical features since it guaranteed a flow of customers who developed a love-hate relationship with their futuristic radios.

Philco Model '37-116 Codes 121 (Shadometer) and 122 (Dial Tuning)

Philco Model '37-116 Codes 121 (Shadometer) and 122 (Dial Tuning), January 1937 Radio-Craft - RF Cafe

(High Fidelity; 530 to 18,200 kc.; Magnetic Tuning (A.F.C.); Automatic Dial on Code 122;.15 tubes (glass); Bass and Treble Tone Controls.)

This all-wave receiver is intended for use with the Philco High-Efficiency Aerial; as it is designed for foreign-broadcast reception on short waves, as well as the standard long­wave bands. If used with this, the red and black terminals of the transmission line are connected to terminals 1 and 2, respectively. With an aerial of ordinary type, the con­nector strap is shifted to rest across terminals 2 and 3; the aerial connected to 1 and the ground to 3.

Both codes include Magnetic Tuning which, with the aid of the Discriminator Tube V8, gives automatic-frequency control ("A.F.C."). The Shadow Meter is a visual tuning indicator showing when resonance has been obtained (by the thinness of the shadow cast by a rotating vane connected with a coil like reception is obtained; the pressure is released and twisting continued until the screw jumps back into its original position. The automatic tuning is now set for that station; and call letters are inserted in the slot below the screw.

To remove the dial, 2 screws holding the handle to the hub are removed; and then 5 screws holding the escutcheon plate to the dial body. The dial may then be removed; 2 fibre and one metal ring will be found around the outer edges. These rings must be taken off to remove the assembly; in replacing them, the spring along the bottom edge of the metal ring must be in correct position, or vibration will be introduced. When the escutcheon is off, control screws may be removed by turning them until the indexing pin on the side end of the screw is centered in the small semicircular slot on the side of the housing; the screw may be then lifted out. (It may be necessary to move it slightly, to mesh its teeth with those in the hole.) To replace, insert screw in hole, turn it half around under pressure until stop on its side will clear shoulder on dial cover hole.

Philco Model '37-116 Codes 121 and 122 Schematic, January 1937 Radio-Craft - RF CafeTo adjust receiver, it is necessary dial be in alignment with condenser. Loosen coupling on condenser shaft, and turn condenser until plates are completely in. Set light beam on index line at low-frequency end of B.C. band; then tighten screws. Turn control until indi­cator is on first division; loosen screws; turn dial until indicator is on index line again; tighten.

Adjustment of I.F. compensators is as follows: (see diagram of compensators) with B.C. range on, M.T. switch off, dial at 580 kc. and test oscillator at 470 kc. connected by condenser to grid of V2. Adjust C29, C28, C31, C30, C33, and C32, in order for maxi­mum output on meter. Turn "Tre.-Sel." control counter-clockwise to "expanded" position; shift oscillator frequency slowly from 460 to 480 kc. Two peaks will appear on meter-about 465 and 475 kc. They are equalized by readjusting C33. Then turn back "Tre.-Sel." control and adjust oscillator coupling for maximum output. Then tune C34 to minimum output.

To adjust the Magnetic Tuning control, leave selector switch on band 1, "Tre.-Sel." control to right and M.T. out. Set oscillator to 1,000 kc, and tune set for max. output. (Tuning control must be accurately adjusted, also oscillator for max.) Turn on M.T. con­trol and adjust C35 for max, output. If meter goes off scale, turn down volume control. Turn off M.T.; the tone of the receiver should not change; if it does, a shift in frequency is shown; and the adjustment repeated.

 

 

Posted August 17, 2017

Radio Service Data Sheets

These schematics, tuning instructions, and other data are reproduced from my collection of vintage radio and electronics magazines. As back in the era, similar schematic and service info was available for purchase from sources such as SAMS Photofacts, but these printings were a no-cost bonus for readers. There are 214 Radio Service Data Sheets as of August 24, 2017.

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